Original Research

Take-Home Points

• Shared decision-making tools, such as predictive models, can help empower the patient to make decisions for or against surgery equipped with more information about the expected outcome.
• There is a role for preoperative collection of PROMs in the clinical decision-making process.
• Mental health state, as reported by the VR-12 MCS, is a significant predictor of postoperative pain and function as reported by the VAS pain and ASES function scores.
• A significant portion of the predictive ability of this model comes from the fact that at 1-year postoperatively, patients receiving a rTSA will on average have a 3.8 point lower on ASES function score than those receiving a TSA (P < .001, ω²=.083).
• Future studies to discern the role of different modalities to improve a patient’s emotional health preoperatively will be beneficial as the healthcare industry trends toward value based medicine collecting PROMs as part of reimbursement schemes.

Over the past few decades, decisions regarding patients’ care have gradually transitioned from a paternalistic model to a more cooperative exchange between patient and physician. Shared decision-making provides patients a measure of autonomy in making choices for their health and their future. Patient participation may mitigate uncertainty and discomfort during selection of a course of treatment, which may lead to increased satisfaction levels after surgery.¹ Moreover, shared decision-making may help patients better manage postoperative expectations through evidenced-based discussions of preoperative health levels and their corresponding outcomes. Patient-reported outcome measures (PROMs) use clinically sensitive and specific metrics to evaluate a patient’s self-reported pain, functional ability, and mental state.² These metrics are useful in setting patient expectations for potential outcomes of treatment options. Use of evidence-based clinical decision-making tools, such as PROM-based predictive models, can facilitate a collaborative decision-making environment for patient and physician. Given the present cost-containment era, and the need for preoperative metrics that can assist in predictive analysis of postoperative improvement, models are clearly valuable.

In attempts to help patients set well-informed and reasonable expectations, physicians have turned to PROMs to facilitate preoperative evidence-based discussions. Although PROMs have been in use for almost 30 years, only recently have they been used to create tools that can aid quantitatively in the surgical decision-making process.^2-6 Combining physical examination findings, imaging studies, comorbidities, and quantitative tools, such as this model, may enhance patients’ understanding of their preoperative condition and expected prognosis and thereby guide their surgical decisions.

We conducted a study to determine whether certain preoperative PROMs can predict 1-year postoperative visual analog scale (VAS) pain scores and American Shoulder and Elbow Surgeons (ASES) Function scores in total shoulder arthroplasty (TSA) and reverse TSA (rTSA). We hypothesized that preoperative mental health status as captured by Veterans RAND 12-Item Health Survey (VR-12) mental health component summary (MCS) score and preoperative VAS pain score would predict both VAS pain score and ASES Function score 1 year after surgery. Specifically, we hypothesized that a higher preoperative VR-12 MCS score would predict less pain and better function 1 year after surgery and that a higher preoperative VAS pain score would predict more pain and worse function 1 year after surgery.

Methods

This study was approved by the Institutional Review Board of Partners Healthcare. The study used the Surgical Outcome System (Arthrex), a comprehensive prospective database that stores preoperative and 1-year postoperative patient demographics and TSA-PROM data. Surveys are emailed to all enrolled patients before surgery and 1 year after surgery. As indicated by the Institutional Review Boards of all participating institutions, patients in the Surgical Outcome System have to sign a consent form to permit use of their responses in research.

The database includes patient data from 42 orthopedic surgeons across the United States. All primary TSAs and primary rTSAs in the database were included in this study, regardless of arthroplasty indication. Revisions were excluded. Also excluded were cases in which the 1-year postoperative questionnaire was not completed. Of the 1681 patients eligible for 1-year follow-up, 1225 (73%) completed the 1-year postoperative questionnaire. PROMs used in the study were VAS pain score, ASES Function score, VR-12 MCS score, and Single Assessment Numerical Evaluation (SANE). Unfortunately, not all surgeons use every measure in the 1-year postoperative questionnaire set. Thus, in our complete models, total number of observations was 1004 for modeling 1-year postoperative VAS pain scores and 986 for modeling 1-year postoperative ASES Function scores. 

Metrics

On VAS, pain is rated from 0 (no pain) to 10 (pain as bad as it can be). Tashjian and colleagues⁷ estimated that the minimal clinically important difference (MCID) for postoperative VAS pain scores was 1.4 in a cohort of 326 patients who had TSA, rTSA, or shoulder hemiarthroplasty. ASES Function score is scaled from 0 to 30, with 30 representing best function.⁸ Wong and colleagues⁹ identified an MCID of 6.5 for ASES Function scores in a cohort of 107 patients who had TSA or rTSA. SANE ratings range from 0% to 100%, with 100% indicating the patient’s shoulder was totally “normal.”10 VR-12 MCS scores appear on a logarithmic scale, with higher numbers representing better mental health. The population mean estimate for VR-12 MCS scores is 50.1 (SD, 11.49; overall possible range, –2.47 to 76.1).11 Our patient population’s scores ranged from 12.5 to 73.8.

Statistical Analysis

Simple bivariate and multivariate linear regressions were performed to evaluate the predictive value of each of the outlined PROMs. Our complete model controls for patient sex, age, and type of arthroplasty. Categorical variables were dummy-coded. Both 1-year postoperative VAS pain score and 1-year postoperative ASES Function score were investigated as dependent variables. Regression coefficients and P and ω² values are reported. Omega square represents how much of the variance in an outcome variable a model explains, like R², and ω² values can also be calculated for individual factors to see how much variance a given factor accounts for. For a simple relative risk calculation, we divided our cohort into 3 equal-sized groups based on preoperative VR-12 MCS scores and compared the risk that patients with scores in the top third (better mental health) would end up below certain ASES Total scores with the risk of patients with scores in the bottom third (worse mental health). All statistical analyses were performed with Stata (StataCorp).

Results

Table 1 lists summary statistics for the population used in these models.

Predicting VAS Pain Score (Table 2)

Preoperative VAS pain score and VR-12 MCS score both predicted 1-year postoperative VAS pain score (P < .001). Preoperative ASES Function score did not predict pain 1 year after surgery. By contrast, higher preoperative VAS pain scores were associated with higher VAS pain scores 1 year after surgery. Higher preoperative VR-12 MCS scores were significantly associated with lower VAS pain scores 1 year after surgery, indicating that better preoperative mental health is significantly associated with better self-reported outcomes in terms of pain 1 year after surgery. These associations remained statistically significant when controlling for age at time of surgery, sex, and type of arthroplasty.

Preoperative VR-12 MCS score was more predictive of 1-year postoperative VAS pain score than preoperative VAS pain score was. In other words, preoperative VR-12 MCS score accounted for more variability in outcome for 1-year postoperative VAS pain score (2.4%; ω² = .023) than preoperative VAS pain score did (1.6%; ω² = .015). 

Predicting ASES Function Score (Table 3)

By contrast, preoperative VAS pain score did not predict 1-year postoperative ASES Function score. Preoperative ASES Function and VR-12 MCS scores both predicted 1-year postoperative ASES Function score (P < .001). Higher preoperative ASES Function scores were associated with higher 1-year postoperative ASES Function scores. In other words, reporting better shoulder function before surgery was associated with reporting better shoulder function after surgery.

An example gives a sense of the effect size associated with the coefficient for preoperative ASES Function score. Our model predicts that, compared with a patient who reports 5 points lower on preoperative ASES Function (which ranges from 0-30), a patient who reports 5 points higher will report on average about 1 point higher on 1-year postoperative ASES Function. As in the model for postoperative pain, these associations with preoperative function and mental health scores held when controlling for age, sex, and type of arthroplasty. 

As in the postoperative pain model, preoperative VR-12 MCS score was more predictive of 1-year postoperative ASES Function score than preoperative ASES Function score was. Preoperative VR-12 MCS score accounted for more of the variation that our model predicts (ω² = .029) than preoperative ASES Function score did (ω² = .020). We compared the risk that patients with high preoperative VR-12 MCS scores (top third of cohort) would end up with ASES Total scores below 70, below 80, or below 90 with the risk of patients with low preoperative VR-12 MCS scores (bottom third). Results appear in Table 4.

A significant part of the predictive ability of our model for postoperative ASES Function scores stems from the fact that a patient who undergoes rTSA (vs TSA) is predicted to have an ASES Function score 3.8 points lower 1 year after surgery (P < .001, ω² = .083). With type of arthroplasty controlled for, female sex is associated with an ASES Function score 1.6 points lower 1 year after surgery (P < .001, ω² = .016).

Preoperative SANE score did not predict 1-year postoperative VAS pain score or ASES Function score. In addition, when our complete model was run with 1-year postoperative SANE score as the dependent variable, preoperative SANE score did not predict 1-year postoperative SANE score. Our data provide no supporting evidence for the use of SANE scores for predictive modeling for shoulder arthroplasty.

Discussion

We prospectively gathered data to determine which factors would predict patient subjective outcomes of primary TSA and primary rTSA. We hypothesized that preoperative VR-12 MCS scores and preoperative VAS pain scores would predict postoperative pain and function as measured with those PROMs. Second, we hypothesized that better preoperative mental health (as measured with VR-12 MCS scores) would predict lower postoperative pain (VAS pain scores) and better postoperative function (ASES Function scores). Third, we hypothesized that higher preoperative pain (VAS pain scores) would correlate with higher postoperative pain (VAS pain scores) and worse postoperative function (ASES Function scores).

Our main goal is to provide patients and surgeons with a predictive model that generates insights into what patients can expect after surgery. This model is not intended to be a screening tool for operative indications, but a clinical tool for helping set expectations.

Our results showed that patients with more pain before surgery were more likely to have more pain 1 year after surgery—confirming the hypothesized relationship between pain before and after surgery. Contrary to the hypothesis, however, degree of pain before surgery was not associated with function 1 year after surgery. Our mental health hypothesis was confirmed: Patients with better preoperative mental health scores had on average less pain and better function 1 year after surgery. Not surprisingly, our model demonstrated that patients with better self-reported function before surgery had better self-reported function after surgery. Patient-reported function before surgery did not significantly affect how much pain the patient had 1 year after surgery. Although we did not hypothesize about the role of function in predicting 1-year outcomes, function is a significant factor to be considered when setting patient expectations regarding shoulder arthroplasty outcomes (Table 5).

Although the effect sizes of each analyzed factor are small, together our models for 1-year postoperative pain and function provide significant insight into patients’ likely outcomes 1 year after TSA and rTSA.

Many studies have found that mental health correlated with pain and function during recovery from orthopedic trauma.^12-18 For example, Wylie and colleagues¹⁹ found that preoperative mental health, as measured with the 36-Item Short Form Health Survey (SF-36) MCS score, predicted patient-reported pain and function in the setting of rotator cuff injury, regardless of treatment type (operative, nonoperative). Others have found that mental health may play a role in how patients report their pain and function on various PROMs.^20,21 Modalities for improving patients’ emotional health baseline may even become a preoperative requirement as the healthcare industry moves toward value-based medicine and collection of patient-related outcomes as part of reimbursement schemes. 

By contrast, some studies have found that preoperative mental health did not predict postoperative outcomes. For example, Kennedy and colleagues²² found that preoperative mental health (as measured with SF-36 MCS scores) did not predict functional outcome in patients with ankle arthritis treated with ankle arthroplasty or arthrodesis. Likewise, Styron and colleagues²³ found no correlation between preoperative mental health (SF-12 MCS scores) and postoperative mental health and function in TSA. Their findings contradict those of the present study and many other studies.^12-18 The contradiction in findings demonstrates the need for well-designed, sufficiently powered studies of the link between preoperative mental health and postoperative outcome. Our study, with its large sample and heterogeneous population, is a start.

Two other groups (Simmen and colleagues,¹⁸ Matsen and colleagues²⁴) have attempted to develop a model predicting outcomes of shoulder arthroplasty. Simmen and colleagues¹⁸ estimated the probability of “treatment success” 1 year after TSA. Their model had 4 factors predictive of patient outcomes. Previous shoulder surgery and age over 75 years were significantly associated with lower probability of success, whereas higher preoperative SF-36 MCS scores and higher preoperative DASH (Disabilities of the Arm, Shoulder, and Hand) Function scores were associated with higher probability of success. The authors deemed TSA successful if the patient achieved a Constant score of ≥80 out of 100. Their model predicts probability of TSA “success,” whereas our models predict particular outcome scores. Both their results and ours support the hypothesis that preoperative mental health and function scores can predict how well a patient fares after surgery. Simmen and colleagues18 based their model on a cohort of only 140 patients and reported a 33.6% success rate (47/140 surgeries).

Matsen and colleagues²⁴ used a 1-practice cohort of 337 patients who underwent different types of arthroplasties, including TSA, rTSA, hemiarthroplasty, and ream-and-run arthroplasty. Although their focus was not preoperative PROMs predicting postoperative PROMs, they used the Simple Shoulder Test (SST) baseline score as a predictive variable. They found that 6 baseline characteristics—American Society of Anesthesiologists class I, shoulder problem unrelated to work, no prior shoulder surgery, glenoid type other than A1, humeral head not superiorly displaced on anteroposterior radiograph, and lower baseline SST score—were statistically associated with better outcomes, and they developed a model driven by these characteristics. They urged other investigators to perform the same kind of analysis with larger patient populations from multiple practices. One of the strengths of our study is its large patient population. We collected data on 1004 patients for modeling 1-year postoperative VAS pain scores and 986 patients for modeling 1-year postoperative ASES Function scores.

Our study had several limitations. First, its data came from a 42-surgeon database, and there may be variations in how these surgeons enroll patients in the registry. If some surgeons did not enroll all their surgical patients, our sample could have been subject to selection bias. Second, in developing our model, we used only patient characteristics that were available in the database. On the other hand, the heterogeneity of the surgeon sample lended external validity to the model. A third limitation was that the model always predicts better pain and function outcomes after TSA than after rTSA. In other words, it does not consider whether TSA is appropriate for a particular patient. Instead, it predicts 1-year shoulder arthroplasty outcomes. 

Our goal here is not to provide outcomes information or a surgical screening tool, but to report on our use of a simple data-driven tool for setting expectations. When appropriate data become available, tools like this should be expanded to predict longer-term shoulder arthroplasty outcomes. We need more studies that combine preoperative PROMs, more baseline clinical and patient characteristics (following the Matsen and colleagues²⁴ model), and large sample sizes.

Conclusion

The educational models presented here can help patients and surgeons learn what to expect after surgery. These models reveal the value in collecting preoperative subjective PROMs and show how a quantitative tool can help facilitate shared decision-making and set patient expectations. Separately, the effect size of each factor is small, but together a patient’s preoperative VAS pain score, ASES Function score, VR-12 MCS score, age, sex, and type of arthroplasty can provide information predictive of the patient’s self-reported pain and function 1 year after surgery.

Take-Home Points

• Shared decision-making tools, such as predictive models, can help empower the patient to make decisions for or against surgery equipped with more information about the expected outcome.
• There is a role for preoperative collection of PROMs in the clinical decision-making process.
• Mental health state, as reported by the VR-12 MCS, is a significant predictor of postoperative pain and function as reported by the VAS pain and ASES function scores.
• A significant portion of the predictive ability of this model comes from the fact that at 1-year postoperatively, patients receiving a rTSA will on average have a 3.8 point lower on ASES function score than those receiving a TSA (P < .001, ω²=.083).
• Future studies to discern the role of different modalities to improve a patient’s emotional health preoperatively will be beneficial as the healthcare industry trends toward value based medicine collecting PROMs as part of reimbursement schemes.

Over the past few decades, decisions regarding patients’ care have gradually transitioned from a paternalistic model to a more cooperative exchange between patient and physician. Shared decision-making provides patients a measure of autonomy in making choices for their health and their future. Patient participation may mitigate uncertainty and discomfort during selection of a course of treatment, which may lead to increased satisfaction levels after surgery.¹ Moreover, shared decision-making may help patients better manage postoperative expectations through evidenced-based discussions of preoperative health levels and their corresponding outcomes. Patient-reported outcome measures (PROMs) use clinically sensitive and specific metrics to evaluate a patient’s self-reported pain, functional ability, and mental state.² These metrics are useful in setting patient expectations for potential outcomes of treatment options. Use of evidence-based clinical decision-making tools, such as PROM-based predictive models, can facilitate a collaborative decision-making environment for patient and physician. Given the present cost-containment era, and the need for preoperative metrics that can assist in predictive analysis of postoperative improvement, models are clearly valuable.

In attempts to help patients set well-informed and reasonable expectations, physicians have turned to PROMs to facilitate preoperative evidence-based discussions. Although PROMs have been in use for almost 30 years, only recently have they been used to create tools that can aid quantitatively in the surgical decision-making process.^2-6 Combining physical examination findings, imaging studies, comorbidities, and quantitative tools, such as this model, may enhance patients’ understanding of their preoperative condition and expected prognosis and thereby guide their surgical decisions.

We conducted a study to determine whether certain preoperative PROMs can predict 1-year postoperative visual analog scale (VAS) pain scores and American Shoulder and Elbow Surgeons (ASES) Function scores in total shoulder arthroplasty (TSA) and reverse TSA (rTSA). We hypothesized that preoperative mental health status as captured by Veterans RAND 12-Item Health Survey (VR-12) mental health component summary (MCS) score and preoperative VAS pain score would predict both VAS pain score and ASES Function score 1 year after surgery. Specifically, we hypothesized that a higher preoperative VR-12 MCS score would predict less pain and better function 1 year after surgery and that a higher preoperative VAS pain score would predict more pain and worse function 1 year after surgery.

Methods

This study was approved by the Institutional Review Board of Partners Healthcare. The study used the Surgical Outcome System (Arthrex), a comprehensive prospective database that stores preoperative and 1-year postoperative patient demographics and TSA-PROM data. Surveys are emailed to all enrolled patients before surgery and 1 year after surgery. As indicated by the Institutional Review Boards of all participating institutions, patients in the Surgical Outcome System have to sign a consent form to permit use of their responses in research.

The database includes patient data from 42 orthopedic surgeons across the United States. All primary TSAs and primary rTSAs in the database were included in this study, regardless of arthroplasty indication. Revisions were excluded. Also excluded were cases in which the 1-year postoperative questionnaire was not completed. Of the 1681 patients eligible for 1-year follow-up, 1225 (73%) completed the 1-year postoperative questionnaire. PROMs used in the study were VAS pain score, ASES Function score, VR-12 MCS score, and Single Assessment Numerical Evaluation (SANE). Unfortunately, not all surgeons use every measure in the 1-year postoperative questionnaire set. Thus, in our complete models, total number of observations was 1004 for modeling 1-year postoperative VAS pain scores and 986 for modeling 1-year postoperative ASES Function scores. 

Metrics

On VAS, pain is rated from 0 (no pain) to 10 (pain as bad as it can be). Tashjian and colleagues⁷ estimated that the minimal clinically important difference (MCID) for postoperative VAS pain scores was 1.4 in a cohort of 326 patients who had TSA, rTSA, or shoulder hemiarthroplasty. ASES Function score is scaled from 0 to 30, with 30 representing best function.⁸ Wong and colleagues⁹ identified an MCID of 6.5 for ASES Function scores in a cohort of 107 patients who had TSA or rTSA. SANE ratings range from 0% to 100%, with 100% indicating the patient’s shoulder was totally “normal.”10 VR-12 MCS scores appear on a logarithmic scale, with higher numbers representing better mental health. The population mean estimate for VR-12 MCS scores is 50.1 (SD, 11.49; overall possible range, –2.47 to 76.1).11 Our patient population’s scores ranged from 12.5 to 73.8.

Statistical Analysis

Simple bivariate and multivariate linear regressions were performed to evaluate the predictive value of each of the outlined PROMs. Our complete model controls for patient sex, age, and type of arthroplasty. Categorical variables were dummy-coded. Both 1-year postoperative VAS pain score and 1-year postoperative ASES Function score were investigated as dependent variables. Regression coefficients and P and ω² values are reported. Omega square represents how much of the variance in an outcome variable a model explains, like R², and ω² values can also be calculated for individual factors to see how much variance a given factor accounts for. For a simple relative risk calculation, we divided our cohort into 3 equal-sized groups based on preoperative VR-12 MCS scores and compared the risk that patients with scores in the top third (better mental health) would end up below certain ASES Total scores with the risk of patients with scores in the bottom third (worse mental health). All statistical analyses were performed with Stata (StataCorp).

Results

Table 1 lists summary statistics for the population used in these models.

Predicting VAS Pain Score (Table 2)

Preoperative VAS pain score and VR-12 MCS score both predicted 1-year postoperative VAS pain score (P < .001). Preoperative ASES Function score did not predict pain 1 year after surgery. By contrast, higher preoperative VAS pain scores were associated with higher VAS pain scores 1 year after surgery. Higher preoperative VR-12 MCS scores were significantly associated with lower VAS pain scores 1 year after surgery, indicating that better preoperative mental health is significantly associated with better self-reported outcomes in terms of pain 1 year after surgery. These associations remained statistically significant when controlling for age at time of surgery, sex, and type of arthroplasty.

Preoperative VR-12 MCS score was more predictive of 1-year postoperative VAS pain score than preoperative VAS pain score was. In other words, preoperative VR-12 MCS score accounted for more variability in outcome for 1-year postoperative VAS pain score (2.4%; ω² = .023) than preoperative VAS pain score did (1.6%; ω² = .015). 

Predicting ASES Function Score (Table 3)

By contrast, preoperative VAS pain score did not predict 1-year postoperative ASES Function score. Preoperative ASES Function and VR-12 MCS scores both predicted 1-year postoperative ASES Function score (P < .001). Higher preoperative ASES Function scores were associated with higher 1-year postoperative ASES Function scores. In other words, reporting better shoulder function before surgery was associated with reporting better shoulder function after surgery.

An example gives a sense of the effect size associated with the coefficient for preoperative ASES Function score. Our model predicts that, compared with a patient who reports 5 points lower on preoperative ASES Function (which ranges from 0-30), a patient who reports 5 points higher will report on average about 1 point higher on 1-year postoperative ASES Function. As in the model for postoperative pain, these associations with preoperative function and mental health scores held when controlling for age, sex, and type of arthroplasty. 

As in the postoperative pain model, preoperative VR-12 MCS score was more predictive of 1-year postoperative ASES Function score than preoperative ASES Function score was. Preoperative VR-12 MCS score accounted for more of the variation that our model predicts (ω² = .029) than preoperative ASES Function score did (ω² = .020). We compared the risk that patients with high preoperative VR-12 MCS scores (top third of cohort) would end up with ASES Total scores below 70, below 80, or below 90 with the risk of patients with low preoperative VR-12 MCS scores (bottom third). Results appear in Table 4.

A significant part of the predictive ability of our model for postoperative ASES Function scores stems from the fact that a patient who undergoes rTSA (vs TSA) is predicted to have an ASES Function score 3.8 points lower 1 year after surgery (P < .001, ω² = .083). With type of arthroplasty controlled for, female sex is associated with an ASES Function score 1.6 points lower 1 year after surgery (P < .001, ω² = .016).

Preoperative SANE score did not predict 1-year postoperative VAS pain score or ASES Function score. In addition, when our complete model was run with 1-year postoperative SANE score as the dependent variable, preoperative SANE score did not predict 1-year postoperative SANE score. Our data provide no supporting evidence for the use of SANE scores for predictive modeling for shoulder arthroplasty.

Discussion

We prospectively gathered data to determine which factors would predict patient subjective outcomes of primary TSA and primary rTSA. We hypothesized that preoperative VR-12 MCS scores and preoperative VAS pain scores would predict postoperative pain and function as measured with those PROMs. Second, we hypothesized that better preoperative mental health (as measured with VR-12 MCS scores) would predict lower postoperative pain (VAS pain scores) and better postoperative function (ASES Function scores). Third, we hypothesized that higher preoperative pain (VAS pain scores) would correlate with higher postoperative pain (VAS pain scores) and worse postoperative function (ASES Function scores).

Our main goal is to provide patients and surgeons with a predictive model that generates insights into what patients can expect after surgery. This model is not intended to be a screening tool for operative indications, but a clinical tool for helping set expectations.

Our results showed that patients with more pain before surgery were more likely to have more pain 1 year after surgery—confirming the hypothesized relationship between pain before and after surgery. Contrary to the hypothesis, however, degree of pain before surgery was not associated with function 1 year after surgery. Our mental health hypothesis was confirmed: Patients with better preoperative mental health scores had on average less pain and better function 1 year after surgery. Not surprisingly, our model demonstrated that patients with better self-reported function before surgery had better self-reported function after surgery. Patient-reported function before surgery did not significantly affect how much pain the patient had 1 year after surgery. Although we did not hypothesize about the role of function in predicting 1-year outcomes, function is a significant factor to be considered when setting patient expectations regarding shoulder arthroplasty outcomes (Table 5).

Although the effect sizes of each analyzed factor are small, together our models for 1-year postoperative pain and function provide significant insight into patients’ likely outcomes 1 year after TSA and rTSA.

Many studies have found that mental health correlated with pain and function during recovery from orthopedic trauma.^12-18 For example, Wylie and colleagues¹⁹ found that preoperative mental health, as measured with the 36-Item Short Form Health Survey (SF-36) MCS score, predicted patient-reported pain and function in the setting of rotator cuff injury, regardless of treatment type (operative, nonoperative). Others have found that mental health may play a role in how patients report their pain and function on various PROMs.^20,21 Modalities for improving patients’ emotional health baseline may even become a preoperative requirement as the healthcare industry moves toward value-based medicine and collection of patient-related outcomes as part of reimbursement schemes. 

By contrast, some studies have found that preoperative mental health did not predict postoperative outcomes. For example, Kennedy and colleagues²² found that preoperative mental health (as measured with SF-36 MCS scores) did not predict functional outcome in patients with ankle arthritis treated with ankle arthroplasty or arthrodesis. Likewise, Styron and colleagues²³ found no correlation between preoperative mental health (SF-12 MCS scores) and postoperative mental health and function in TSA. Their findings contradict those of the present study and many other studies.^12-18 The contradiction in findings demonstrates the need for well-designed, sufficiently powered studies of the link between preoperative mental health and postoperative outcome. Our study, with its large sample and heterogeneous population, is a start.

Two other groups (Simmen and colleagues,¹⁸ Matsen and colleagues²⁴) have attempted to develop a model predicting outcomes of shoulder arthroplasty. Simmen and colleagues¹⁸ estimated the probability of “treatment success” 1 year after TSA. Their model had 4 factors predictive of patient outcomes. Previous shoulder surgery and age over 75 years were significantly associated with lower probability of success, whereas higher preoperative SF-36 MCS scores and higher preoperative DASH (Disabilities of the Arm, Shoulder, and Hand) Function scores were associated with higher probability of success. The authors deemed TSA successful if the patient achieved a Constant score of ≥80 out of 100. Their model predicts probability of TSA “success,” whereas our models predict particular outcome scores. Both their results and ours support the hypothesis that preoperative mental health and function scores can predict how well a patient fares after surgery. Simmen and colleagues18 based their model on a cohort of only 140 patients and reported a 33.6% success rate (47/140 surgeries).

Matsen and colleagues²⁴ used a 1-practice cohort of 337 patients who underwent different types of arthroplasties, including TSA, rTSA, hemiarthroplasty, and ream-and-run arthroplasty. Although their focus was not preoperative PROMs predicting postoperative PROMs, they used the Simple Shoulder Test (SST) baseline score as a predictive variable. They found that 6 baseline characteristics—American Society of Anesthesiologists class I, shoulder problem unrelated to work, no prior shoulder surgery, glenoid type other than A1, humeral head not superiorly displaced on anteroposterior radiograph, and lower baseline SST score—were statistically associated with better outcomes, and they developed a model driven by these characteristics. They urged other investigators to perform the same kind of analysis with larger patient populations from multiple practices. One of the strengths of our study is its large patient population. We collected data on 1004 patients for modeling 1-year postoperative VAS pain scores and 986 patients for modeling 1-year postoperative ASES Function scores.

Our study had several limitations. First, its data came from a 42-surgeon database, and there may be variations in how these surgeons enroll patients in the registry. If some surgeons did not enroll all their surgical patients, our sample could have been subject to selection bias. Second, in developing our model, we used only patient characteristics that were available in the database. On the other hand, the heterogeneity of the surgeon sample lended external validity to the model. A third limitation was that the model always predicts better pain and function outcomes after TSA than after rTSA. In other words, it does not consider whether TSA is appropriate for a particular patient. Instead, it predicts 1-year shoulder arthroplasty outcomes. 

Our goal here is not to provide outcomes information or a surgical screening tool, but to report on our use of a simple data-driven tool for setting expectations. When appropriate data become available, tools like this should be expanded to predict longer-term shoulder arthroplasty outcomes. We need more studies that combine preoperative PROMs, more baseline clinical and patient characteristics (following the Matsen and colleagues²⁴ model), and large sample sizes.

Conclusion

The educational models presented here can help patients and surgeons learn what to expect after surgery. These models reveal the value in collecting preoperative subjective PROMs and show how a quantitative tool can help facilitate shared decision-making and set patient expectations. Separately, the effect size of each factor is small, but together a patient’s preoperative VAS pain score, ASES Function score, VR-12 MCS score, age, sex, and type of arthroplasty can provide information predictive of the patient’s self-reported pain and function 1 year after surgery.

Take-Home Points

• Shared decision-making tools, such as predictive models, can help empower the patient to make decisions for or against surgery equipped with more information about the expected outcome.
• There is a role for preoperative collection of PROMs in the clinical decision-making process.
• Mental health state, as reported by the VR-12 MCS, is a significant predictor of postoperative pain and function as reported by the VAS pain and ASES function scores.
• A significant portion of the predictive ability of this model comes from the fact that at 1-year postoperatively, patients receiving a rTSA will on average have a 3.8 point lower on ASES function score than those receiving a TSA (P < .001, ω²=.083).
• Future studies to discern the role of different modalities to improve a patient’s emotional health preoperatively will be beneficial as the healthcare industry trends toward value based medicine collecting PROMs as part of reimbursement schemes.

Over the past few decades, decisions regarding patients’ care have gradually transitioned from a paternalistic model to a more cooperative exchange between patient and physician. Shared decision-making provides patients a measure of autonomy in making choices for their health and their future. Patient participation may mitigate uncertainty and discomfort during selection of a course of treatment, which may lead to increased satisfaction levels after surgery.¹ Moreover, shared decision-making may help patients better manage postoperative expectations through evidenced-based discussions of preoperative health levels and their corresponding outcomes. Patient-reported outcome measures (PROMs) use clinically sensitive and specific metrics to evaluate a patient’s self-reported pain, functional ability, and mental state.² These metrics are useful in setting patient expectations for potential outcomes of treatment options. Use of evidence-based clinical decision-making tools, such as PROM-based predictive models, can facilitate a collaborative decision-making environment for patient and physician. Given the present cost-containment era, and the need for preoperative metrics that can assist in predictive analysis of postoperative improvement, models are clearly valuable.

In attempts to help patients set well-informed and reasonable expectations, physicians have turned to PROMs to facilitate preoperative evidence-based discussions. Although PROMs have been in use for almost 30 years, only recently have they been used to create tools that can aid quantitatively in the surgical decision-making process.^2-6 Combining physical examination findings, imaging studies, comorbidities, and quantitative tools, such as this model, may enhance patients’ understanding of their preoperative condition and expected prognosis and thereby guide their surgical decisions.

We conducted a study to determine whether certain preoperative PROMs can predict 1-year postoperative visual analog scale (VAS) pain scores and American Shoulder and Elbow Surgeons (ASES) Function scores in total shoulder arthroplasty (TSA) and reverse TSA (rTSA). We hypothesized that preoperative mental health status as captured by Veterans RAND 12-Item Health Survey (VR-12) mental health component summary (MCS) score and preoperative VAS pain score would predict both VAS pain score and ASES Function score 1 year after surgery. Specifically, we hypothesized that a higher preoperative VR-12 MCS score would predict less pain and better function 1 year after surgery and that a higher preoperative VAS pain score would predict more pain and worse function 1 year after surgery.

Methods

This study was approved by the Institutional Review Board of Partners Healthcare. The study used the Surgical Outcome System (Arthrex), a comprehensive prospective database that stores preoperative and 1-year postoperative patient demographics and TSA-PROM data. Surveys are emailed to all enrolled patients before surgery and 1 year after surgery. As indicated by the Institutional Review Boards of all participating institutions, patients in the Surgical Outcome System have to sign a consent form to permit use of their responses in research.

The database includes patient data from 42 orthopedic surgeons across the United States. All primary TSAs and primary rTSAs in the database were included in this study, regardless of arthroplasty indication. Revisions were excluded. Also excluded were cases in which the 1-year postoperative questionnaire was not completed. Of the 1681 patients eligible for 1-year follow-up, 1225 (73%) completed the 1-year postoperative questionnaire. PROMs used in the study were VAS pain score, ASES Function score, VR-12 MCS score, and Single Assessment Numerical Evaluation (SANE). Unfortunately, not all surgeons use every measure in the 1-year postoperative questionnaire set. Thus, in our complete models, total number of observations was 1004 for modeling 1-year postoperative VAS pain scores and 986 for modeling 1-year postoperative ASES Function scores. 

Metrics

On VAS, pain is rated from 0 (no pain) to 10 (pain as bad as it can be). Tashjian and colleagues⁷ estimated that the minimal clinically important difference (MCID) for postoperative VAS pain scores was 1.4 in a cohort of 326 patients who had TSA, rTSA, or shoulder hemiarthroplasty. ASES Function score is scaled from 0 to 30, with 30 representing best function.⁸ Wong and colleagues⁹ identified an MCID of 6.5 for ASES Function scores in a cohort of 107 patients who had TSA or rTSA. SANE ratings range from 0% to 100%, with 100% indicating the patient’s shoulder was totally “normal.”10 VR-12 MCS scores appear on a logarithmic scale, with higher numbers representing better mental health. The population mean estimate for VR-12 MCS scores is 50.1 (SD, 11.49; overall possible range, –2.47 to 76.1).11 Our patient population’s scores ranged from 12.5 to 73.8.

Statistical Analysis

Simple bivariate and multivariate linear regressions were performed to evaluate the predictive value of each of the outlined PROMs. Our complete model controls for patient sex, age, and type of arthroplasty. Categorical variables were dummy-coded. Both 1-year postoperative VAS pain score and 1-year postoperative ASES Function score were investigated as dependent variables. Regression coefficients and P and ω² values are reported. Omega square represents how much of the variance in an outcome variable a model explains, like R², and ω² values can also be calculated for individual factors to see how much variance a given factor accounts for. For a simple relative risk calculation, we divided our cohort into 3 equal-sized groups based on preoperative VR-12 MCS scores and compared the risk that patients with scores in the top third (better mental health) would end up below certain ASES Total scores with the risk of patients with scores in the bottom third (worse mental health). All statistical analyses were performed with Stata (StataCorp).

Results

Table 1 lists summary statistics for the population used in these models.

Predicting VAS Pain Score (Table 2)

Preoperative VAS pain score and VR-12 MCS score both predicted 1-year postoperative VAS pain score (P < .001). Preoperative ASES Function score did not predict pain 1 year after surgery. By contrast, higher preoperative VAS pain scores were associated with higher VAS pain scores 1 year after surgery. Higher preoperative VR-12 MCS scores were significantly associated with lower VAS pain scores 1 year after surgery, indicating that better preoperative mental health is significantly associated with better self-reported outcomes in terms of pain 1 year after surgery. These associations remained statistically significant when controlling for age at time of surgery, sex, and type of arthroplasty.

Preoperative VR-12 MCS score was more predictive of 1-year postoperative VAS pain score than preoperative VAS pain score was. In other words, preoperative VR-12 MCS score accounted for more variability in outcome for 1-year postoperative VAS pain score (2.4%; ω² = .023) than preoperative VAS pain score did (1.6%; ω² = .015). 

Predicting ASES Function Score (Table 3)

By contrast, preoperative VAS pain score did not predict 1-year postoperative ASES Function score. Preoperative ASES Function and VR-12 MCS scores both predicted 1-year postoperative ASES Function score (P < .001). Higher preoperative ASES Function scores were associated with higher 1-year postoperative ASES Function scores. In other words, reporting better shoulder function before surgery was associated with reporting better shoulder function after surgery.

An example gives a sense of the effect size associated with the coefficient for preoperative ASES Function score. Our model predicts that, compared with a patient who reports 5 points lower on preoperative ASES Function (which ranges from 0-30), a patient who reports 5 points higher will report on average about 1 point higher on 1-year postoperative ASES Function. As in the model for postoperative pain, these associations with preoperative function and mental health scores held when controlling for age, sex, and type of arthroplasty. 

As in the postoperative pain model, preoperative VR-12 MCS score was more predictive of 1-year postoperative ASES Function score than preoperative ASES Function score was. Preoperative VR-12 MCS score accounted for more of the variation that our model predicts (ω² = .029) than preoperative ASES Function score did (ω² = .020). We compared the risk that patients with high preoperative VR-12 MCS scores (top third of cohort) would end up with ASES Total scores below 70, below 80, or below 90 with the risk of patients with low preoperative VR-12 MCS scores (bottom third). Results appear in Table 4.

A significant part of the predictive ability of our model for postoperative ASES Function scores stems from the fact that a patient who undergoes rTSA (vs TSA) is predicted to have an ASES Function score 3.8 points lower 1 year after surgery (P < .001, ω² = .083). With type of arthroplasty controlled for, female sex is associated with an ASES Function score 1.6 points lower 1 year after surgery (P < .001, ω² = .016).

Preoperative SANE score did not predict 1-year postoperative VAS pain score or ASES Function score. In addition, when our complete model was run with 1-year postoperative SANE score as the dependent variable, preoperative SANE score did not predict 1-year postoperative SANE score. Our data provide no supporting evidence for the use of SANE scores for predictive modeling for shoulder arthroplasty.

Discussion

We prospectively gathered data to determine which factors would predict patient subjective outcomes of primary TSA and primary rTSA. We hypothesized that preoperative VR-12 MCS scores and preoperative VAS pain scores would predict postoperative pain and function as measured with those PROMs. Second, we hypothesized that better preoperative mental health (as measured with VR-12 MCS scores) would predict lower postoperative pain (VAS pain scores) and better postoperative function (ASES Function scores). Third, we hypothesized that higher preoperative pain (VAS pain scores) would correlate with higher postoperative pain (VAS pain scores) and worse postoperative function (ASES Function scores).

Our main goal is to provide patients and surgeons with a predictive model that generates insights into what patients can expect after surgery. This model is not intended to be a screening tool for operative indications, but a clinical tool for helping set expectations.

Our results showed that patients with more pain before surgery were more likely to have more pain 1 year after surgery—confirming the hypothesized relationship between pain before and after surgery. Contrary to the hypothesis, however, degree of pain before surgery was not associated with function 1 year after surgery. Our mental health hypothesis was confirmed: Patients with better preoperative mental health scores had on average less pain and better function 1 year after surgery. Not surprisingly, our model demonstrated that patients with better self-reported function before surgery had better self-reported function after surgery. Patient-reported function before surgery did not significantly affect how much pain the patient had 1 year after surgery. Although we did not hypothesize about the role of function in predicting 1-year outcomes, function is a significant factor to be considered when setting patient expectations regarding shoulder arthroplasty outcomes (Table 5).

Although the effect sizes of each analyzed factor are small, together our models for 1-year postoperative pain and function provide significant insight into patients’ likely outcomes 1 year after TSA and rTSA.

Many studies have found that mental health correlated with pain and function during recovery from orthopedic trauma.^12-18 For example, Wylie and colleagues¹⁹ found that preoperative mental health, as measured with the 36-Item Short Form Health Survey (SF-36) MCS score, predicted patient-reported pain and function in the setting of rotator cuff injury, regardless of treatment type (operative, nonoperative). Others have found that mental health may play a role in how patients report their pain and function on various PROMs.^20,21 Modalities for improving patients’ emotional health baseline may even become a preoperative requirement as the healthcare industry moves toward value-based medicine and collection of patient-related outcomes as part of reimbursement schemes. 

By contrast, some studies have found that preoperative mental health did not predict postoperative outcomes. For example, Kennedy and colleagues²² found that preoperative mental health (as measured with SF-36 MCS scores) did not predict functional outcome in patients with ankle arthritis treated with ankle arthroplasty or arthrodesis. Likewise, Styron and colleagues²³ found no correlation between preoperative mental health (SF-12 MCS scores) and postoperative mental health and function in TSA. Their findings contradict those of the present study and many other studies.^12-18 The contradiction in findings demonstrates the need for well-designed, sufficiently powered studies of the link between preoperative mental health and postoperative outcome. Our study, with its large sample and heterogeneous population, is a start.

Two other groups (Simmen and colleagues,¹⁸ Matsen and colleagues²⁴) have attempted to develop a model predicting outcomes of shoulder arthroplasty. Simmen and colleagues¹⁸ estimated the probability of “treatment success” 1 year after TSA. Their model had 4 factors predictive of patient outcomes. Previous shoulder surgery and age over 75 years were significantly associated with lower probability of success, whereas higher preoperative SF-36 MCS scores and higher preoperative DASH (Disabilities of the Arm, Shoulder, and Hand) Function scores were associated with higher probability of success. The authors deemed TSA successful if the patient achieved a Constant score of ≥80 out of 100. Their model predicts probability of TSA “success,” whereas our models predict particular outcome scores. Both their results and ours support the hypothesis that preoperative mental health and function scores can predict how well a patient fares after surgery. Simmen and colleagues18 based their model on a cohort of only 140 patients and reported a 33.6% success rate (47/140 surgeries).

Matsen and colleagues²⁴ used a 1-practice cohort of 337 patients who underwent different types of arthroplasties, including TSA, rTSA, hemiarthroplasty, and ream-and-run arthroplasty. Although their focus was not preoperative PROMs predicting postoperative PROMs, they used the Simple Shoulder Test (SST) baseline score as a predictive variable. They found that 6 baseline characteristics—American Society of Anesthesiologists class I, shoulder problem unrelated to work, no prior shoulder surgery, glenoid type other than A1, humeral head not superiorly displaced on anteroposterior radiograph, and lower baseline SST score—were statistically associated with better outcomes, and they developed a model driven by these characteristics. They urged other investigators to perform the same kind of analysis with larger patient populations from multiple practices. One of the strengths of our study is its large patient population. We collected data on 1004 patients for modeling 1-year postoperative VAS pain scores and 986 patients for modeling 1-year postoperative ASES Function scores.

Our study had several limitations. First, its data came from a 42-surgeon database, and there may be variations in how these surgeons enroll patients in the registry. If some surgeons did not enroll all their surgical patients, our sample could have been subject to selection bias. Second, in developing our model, we used only patient characteristics that were available in the database. On the other hand, the heterogeneity of the surgeon sample lended external validity to the model. A third limitation was that the model always predicts better pain and function outcomes after TSA than after rTSA. In other words, it does not consider whether TSA is appropriate for a particular patient. Instead, it predicts 1-year shoulder arthroplasty outcomes. 

Our goal here is not to provide outcomes information or a surgical screening tool, but to report on our use of a simple data-driven tool for setting expectations. When appropriate data become available, tools like this should be expanded to predict longer-term shoulder arthroplasty outcomes. We need more studies that combine preoperative PROMs, more baseline clinical and patient characteristics (following the Matsen and colleagues²⁴ model), and large sample sizes.

Conclusion

The educational models presented here can help patients and surgeons learn what to expect after surgery. These models reveal the value in collecting preoperative subjective PROMs and show how a quantitative tool can help facilitate shared decision-making and set patient expectations. Separately, the effect size of each factor is small, but together a patient’s preoperative VAS pain score, ASES Function score, VR-12 MCS score, age, sex, and type of arthroplasty can provide information predictive of the patient’s self-reported pain and function 1 year after surgery.

Take-Home Points

• The authors have developed a total shoulder glenoid prosthesis that conforms with the humeral head in its center and is nonconforming on its peripheral edge.
• All clinical survey and range of motion parameters demonstrated statistically significant improvements at final follow-up.
• Only 3 shoulders (1.7%) required revision surgery.
• Eighty-six (63%) of 136 shoulders demonstrated no radiographic evidence of glenoid loosening.
• This is the first and largest study that evaluates the clinical and radiographic outcomes of this hybrid shoulder prosthesis.

Fixation of the glenoid component is the limiting factor in modern total shoulder arthroplasty (TSA). Glenoid loosening, the most common long-term complication, necessitates revision in up to 12% of patients.^1-4 By contrast, humeral component loosening is relatively uncommon, affecting as few as 0.34% of patients.⁵ Multiple long-term studies have found consistently high rates (45%-93%) of radiolucencies around the glenoid component.^3,6,7 Although their clinical significance has been debated, radiolucencies around the glenoid component raise concern about progressive loss of fixation.

Since TSA was introduced in the 1970s, complications with the glenoid component have been addressed with 2 different designs: conforming (congruent) and nonconforming. In a congruent articulation, the radii of curvature of the glenoid and humeral head components are identical, whereas they differ in a nonconforming model. Joint conformity is inversely related to glenohumeral translation.⁸ Neer’s original TSA was made congruent in order to limit translation and maximize the contact area. However, this design results in edge loading and a so-called rocking-horse phenomenon, which may lead to glenoid loosening.^9-13 Surgeons therefore have increasingly turned to nonconforming implants. In the nonconforming design, the radius of curvature of the humeral head is smaller than that of the glenoid. Although this design may reduce edge loading,¹⁴ it allows more translation and reduces the relative contact area of the glenohumeral joint. As a result, more contact stress is transmitted to the glenoid component, leading to polyethylene deformation and wear.^15,16

Dual radii of curvature are designed to augment joint stability without increasing component wear. Biomechanical data have indicated that edge loading is not increased by having a central conforming region added to a nonconforming model.¹⁷ The clinical value of this prosthesis, however, has not been determined. Therefore, we conducted a study to describe the intermediate-term clinical and radiographic outcomes of TSAs that use a novel hybrid glenoid component.

Materials and Methods

This study was approved (protocol AAAD3473) by the Institutional Review Board of Columbia University and was conducted in compliance with Health Insurance Portability and Accountability Act (HIPAA) regulations.

Patient Selection

At Columbia University Medical Center, Dr. Bigliani performed 196 TSAs with a hybrid glenoid component (Bigliani-Flatow; Zimmer Biomet) in 169 patients between September 1998 and November 2007. All patients had received a diagnosis of primary glenohumeral arthritis as defined by Neer.¹⁸ Patients with previous surgery such as rotator cuff repair or subacromial decompression were included in our review, and patients with a nonprimary form of arthritis, such as rheumatoid, posttraumatic, or post-capsulorrhaphy arthritis, were excluded.

Operative Technique

For all surgeries, Dr. Bigliani performed a subscapularis tenotomy with regional anesthesia and a standard deltopectoral approach. A partial anterior capsulectomy was performed to increase the glenoid’s visibility. The inferior labrum was removed with a needle-tip bovie while the axillary nerve was being protected with a metal finger or narrow Darrach retractor. After reaming and trialing, the final glenoid component was cemented into place. Cement was placed only in the peg or keel holes and pressurized twice before final implantation. Of the 196 glenoid components, 168 (86%) were pegged and 28 (14%) keeled; in addition,190 of these components were all-polyethylene, whereas 6 had trabecular-metal backing. All glenoid components incorporated the hybrid design of dual radii of curvature. After the glenoid was cemented, the final humeral component was placed in 30° of retroversion. Whenever posterior wear was found, retroversion was reduced by 5° to 10°. The humeral prosthesis was cemented in cases (104/196, 53%) of poor bone quality or a large canal.

After surgery, the patient’s sling was fitted with an abduction pillow and a swathe, to be worn the first 24 hours, and the arm was passively ranged. Patients typically were discharged on postoperative day 2. Then, for 2 weeks, they followed an assisted passive range of motion (ROM) protocol, with limited external rotation, for promotion of subscapularis healing.

Clinical Outcomes

Dr. Bigliani assessed preoperative ROM in all planes. During initial evaluation, patients completed a questionnaire that consisted of the 36-Item Short Form Health Survey^19,20 (SF-36) and the American Shoulder and Elbow Surgeons²¹ (ASES) and Simple Shoulder Test²² (SST) surveys. Postoperative clinical data were collected from office follow-up visits, survey questionnaires, or both. Postoperative office data included ROM, subscapularis integrity testing (belly-press or lift-off), and any complications. Patients with <1 year of office follow-up were excluded. In addition, the same survey questionnaire that was used before surgery was mailed to all patients after surgery; then, for anyone who did not respond by mail, we attempted contact by telephone. Neer criteria were based on patients’ subjective assessment of each arm on a 3-point Likert scale (1 = very satisfied, 2 = satisfied, 3 = dissatisfied). Patients were also asked about any specific complications or revision operations since their index procedure.

Physical examination and office follow-up data were obtained for 129 patients (148/196 shoulders, 76% follow-up) at a mean of 3.7 years (range 1.0-10.2 years) after surgery. Surveys were completed by 117 patients (139/196 shoulders, 71% follow-up) at a mean of 5.1 years (range, 1.6-11.2 years) after surgery. Only 15 patients had neither 1 year of office follow-up nor a completed questionnaire. The remaining 154 patients (178/196 shoulders, 91% follow-up) had clinical follow-up with office, mail, or telephone questionnaire at a mean of 4.8 years (range, 1.0-11.2 years) after surgery. This cohort of patients was used to determine rates of surgical revisions, subscapularis tears, dislocations, and other complications.

Radiographic Outcomes

Patients were included in the radiographic analysis if they had a shoulder radiograph at least 1 year after surgery. One hundred nineteen patients (136/196 shoulders, 69% follow-up) had radiographic follow-up at a mean of 3.7 years (range, 1.0-9.4 years) after surgery.

Statistical Analysis

Statistical analysis was performed with Stata Version 10.0. Paired t tests were used to compare preoperative and postoperative numerical data, including ROM and survey scores. We calculated 95% confidence intervals (CIs) and set statistical significance at P < .05. For qualitative measures, the Fisher exact test was used. Survivorship analysis was performed according to the Kaplan-Meier method, with right-censored data for no event or missing data.²⁵

Results

Clinical Analysis of Demographics

In demographics, the clinical and radiographic patient subgroups were similar to each other and to the overall study population (Table 2). Of 196 patients overall, 16 (8%) had a concomitant rotator cuff repair, and 27 (14%) underwent staged bilateral shoulder arthroplasties.

Clinical Analysis of ROM and Survey Scores

Operative shoulder ROM in forward elevation, external rotation at side, external rotation in abduction, and internal rotation all showed statistically significant (P < .001) improvement from before surgery to after surgery. Over 3.7 years, mean (SD) forward elevation improved from 107.3° (34.8°) to 159.0° (29.4°), external rotation at side improved from 20.4° (16.7°) to 49.4° (11.3°), and external rotation in abduction improved from 53.7° (24.3°) to 84.7° (9.1°). Internal rotation improved from a mean (SD) vertebral level of S1 (6.0 levels) to T9 (3.7 levels).

All validated survey scores also showed statistically significant (P < .001) improvement from before surgery to after surgery. Over 5.1 years, mean (SD) SF-36 scores improved from 64.9 (13.4) to 73.6 (17.1), ASES scores improved from 41.1 (22.5) to 82.7 (17.7), SST scores improved from 3.9 (2.8) to 9.7 (2.2), and visual analog scale pain scores improved from 5.6 (3.2) to 1.4 (2.1). Of 139 patients with follow-up, 130 (93.5%) were either satisfied or very satisfied with their TSA, and only 119 (86%) were either satisfied or very satisfied with the nonoperative shoulder.

Clinical Analysis of Postoperative Complications

Of the 178 shoulders evaluated for complications, 3 (1.7%) underwent revision surgery. Mean time to revision was 2.3 years (range, 1.5-3.9 years). Two revisions involved the glenoid component, and the third involved the humerus. In one of the glenoid cases, a 77-year-old woman fell and sustained a fracture at the base of the trabecular metal glenoid pegs; her component was revised to an all-polyethylene component, and she had no further complications. In the other glenoid case, a 73-year-old man’s all-polyethylene component loosened after 2 years and was revised to a trabecular metal implant, which loosened as well and was later converted to a hemiarthroplasty. In the humeral case, a 33-year-old man had his 4-year-old index TSA revised to a cemented stem and had no further complications.

Table 4 compares the clinical and radiographic outcomes of patients who required subscapularis repair, capsular shift, or implant revision with the outcomes of all other study patients, and Figure 3 shows Kaplan-Meier survivorship.

Postoperative Radiographic Analysis

Glenoid Component. At a mean of 3.7 years (minimum, 1 year) after surgery, 86 (63%) of 136 radiographically evaluated shoulders showed no glenoid lucencies; the other 50 (37%) showed ≥1 lucency. Of the 136 shoulders, 33 (24%) had a Lazarus score of 1, 15 (11%) had a score of 2, and only 2 (2%) had a score of 3. None of the shoulders had a score of 4 or 5.

Humeral Component. Of the 136 shoulders, 91 (67%) showed no lucencies in any of the 8 humeral stem zones; the other 45 (33%) showed 1 to 3 lucencies. Thirty (22%) of the 136 shoulders had 1 stem lucency zone, 8 (6%) had 2, and 3 (2%) had 3. None of the shoulders had >3 periprosthetic zones with lucent lines.

Discussion

In this article, we describe a hybrid glenoid TSA component with dual radii of curvature. Its central portion is congruent with the humeral head, and its peripheral portion is noncongruent and larger. The most significant finding of our study is the low rate (1.1%) of glenoid component revision 4.8 years after surgery. This rate is the lowest that has been reported in a study of ≥100 patients. Overall implant survival appeared as an almost flat Kaplan-Meir curve. We attribute this low revision rate to improved biomechanics with the hybrid glenoid design. 

Symptomatic glenoid component loosening is the most common TSA complication.^1,26-28 In a review of 73 Neer TSAs, Cofield7 found glenoid radiolucencies in 71% of patients 3.8 years after surgery. Radiographic evidence of loosening, defined as component migration, or tilt, or a circumferential lucency 1.5 mm thick, was present in another 11% of patients, and 4.1% developed symptomatic loosening that required glenoid revision. In a study with 12.2-year follow-up, Torchia and colleagues³ found rates of 84% for glenoid radiolucencies, 44% for radiographic loosening, and 5.6% for symptomatic loosening that required revision. In a systematic review of studies with follow-up of ≥10 years, Bohsali and colleagues²⁷ found similar lucency and radiographic loosening rates and a 7% glenoid revision rate. These data suggest glenoid radiolucencies may progress to component loosening.

Degree of joint congruence is a key factor in glenoid loosening. Neer’s congruent design increases the contact area with concentric loading and reduces glenohumeral translation, which leads to reduced polyethylene wear and improved joint stability. In extreme arm positions, however, humeral head subluxation results in edge loading and a glenoid rocking-horse effect.^{9-13,17,29-31} Conversely, nonconforming implants allow increased glenohumeral translation without edge loading,¹⁴ though they also reduce the relative glenohumeral contact area and thus transmit more contact stress to the glenoid.^16,17 A hybrid glenoid component with central conforming and peripheral nonconforming zones may reduce the rocking-horse effect while maximizing ROM and joint stability. Wang and colleagues32 studied the biomechanical properties of this glenoid design and found that the addition of a central conforming region did not increase edge loading.

Additional results from our study support the efficacy of a hybrid glenoid component. Patients’ clinical outcomes improved significantly. At 5.1 years after surgery, 93.5% of patients were satisfied or very satisfied with their procedure and reported less satisfaction (86%) with the nonoperative shoulder. Also significant was the reduced number of radiolucencies. At 3.7 years after surgery, the overall percentage of shoulders with ≥1 glenoid radiolucency was 37%, considerably lower than the 82% reported by Cofield7 and the rates in more recent studies.^3,16,33-36 Of the 178 shoulders in our study, 10 (5.6%) had subscapularis tears, and 6 (3.4%) of 178 had these tears surgically repaired. This 3.4% compares favorably with the 5.9% (of 119 patients) found by Miller and colleagues37 28 months after surgery. Of our 178 shoulders, 27 (15.2%) had clinically significant postoperative complications; 18 (10.1%) of the 178 had these complications surgically treated, and 9 (5.1%) had them managed nonoperatively. Bohsali and colleagues²⁷ systematically reviewed 33 TSA studies and found a slightly higher complication rate (16.3%) 5.3 years after surgery. Furthermore, in our study, the 11 patients who underwent revision, capsular shift, or subscapularis repair had final outcomes comparable to those of the rest of our study population.

Our study had several potential weaknesses. First, its minimum clinical and radiographic follow-up was 1 year, whereas most long-term TSA series set a minimum of 2 years. We used 1 year because this was the first clinical study of the hybrid glenoid component design, and we wanted to maximize its sample size by reporting on intermediate-length outcomes. Even so, 93% (166/178) of our clinical patients and 83% (113/136) of our radiographic patients have had ≥2 years of follow-up, and we continue to follow all study patients for long-term outcomes. Another weakness of the study was its lack of a uniform group of patients with all the office, survey, complications, and radiographic data. Our retrospective study design made it difficult to obtain such a group without significantly reducing the sample size, so we divided patients into 4 data groups. A third potential weakness was the study’s variable method for collecting complications data. Rates of complications in the 178 shoulders were calculated from either office evaluation or patient self-report by mail or telephone. This data collection method is subject to recall bias, but mail and telephone contact was needed so the study would capture the large number of patients who had traveled to our institution for their surgery or had since moved away. Fourth, belly-press and lift-off tests were used in part to assess subscapularis function, but recent literature suggests post-TSA subscapularis assessment can be unreliable.³⁸ These tests may be positive in up to two-thirds of patients after 2 years.³⁹ Fifth, the generalizability of our findings to diagnoses such as rheumatoid and posttraumatic arthritis is limited. We had to restrict the study to patients with primary glenohumeral arthritis in order to minimize confounders.

This study’s main strength is its description of the clinical and radiographic outcomes of using a single prosthetic system in operations performed by a single surgeon in a large number of patients. This was the first and largest study evaluating the clinical and radiographic outcomes of this hybrid glenoid implant. Excluding patients with nonprimary arthritis allowed us to minimize potential confounding factors that affect patient outcomes. In conclusion, our study results showed the favorable clinical and radiographic outcomes of TSAs that have a hybrid glenoid component with dual radii of curvature. At a mean of 3.7 years after surgery, 63% of patients had no glenoid lucencies, and, at a mean of 4.8 years, only 1.7% of patients required revision. We continue to follow these patients to obtain long-term results of this innovative prosthesis.

Take-Home Points

• The authors have developed a total shoulder glenoid prosthesis that conforms with the humeral head in its center and is nonconforming on its peripheral edge.
• All clinical survey and range of motion parameters demonstrated statistically significant improvements at final follow-up.
• Only 3 shoulders (1.7%) required revision surgery.
• Eighty-six (63%) of 136 shoulders demonstrated no radiographic evidence of glenoid loosening.
• This is the first and largest study that evaluates the clinical and radiographic outcomes of this hybrid shoulder prosthesis.

Fixation of the glenoid component is the limiting factor in modern total shoulder arthroplasty (TSA). Glenoid loosening, the most common long-term complication, necessitates revision in up to 12% of patients.^1-4 By contrast, humeral component loosening is relatively uncommon, affecting as few as 0.34% of patients.⁵ Multiple long-term studies have found consistently high rates (45%-93%) of radiolucencies around the glenoid component.^3,6,7 Although their clinical significance has been debated, radiolucencies around the glenoid component raise concern about progressive loss of fixation.

Since TSA was introduced in the 1970s, complications with the glenoid component have been addressed with 2 different designs: conforming (congruent) and nonconforming. In a congruent articulation, the radii of curvature of the glenoid and humeral head components are identical, whereas they differ in a nonconforming model. Joint conformity is inversely related to glenohumeral translation.⁸ Neer’s original TSA was made congruent in order to limit translation and maximize the contact area. However, this design results in edge loading and a so-called rocking-horse phenomenon, which may lead to glenoid loosening.^9-13 Surgeons therefore have increasingly turned to nonconforming implants. In the nonconforming design, the radius of curvature of the humeral head is smaller than that of the glenoid. Although this design may reduce edge loading,¹⁴ it allows more translation and reduces the relative contact area of the glenohumeral joint. As a result, more contact stress is transmitted to the glenoid component, leading to polyethylene deformation and wear.^15,16

Dual radii of curvature are designed to augment joint stability without increasing component wear. Biomechanical data have indicated that edge loading is not increased by having a central conforming region added to a nonconforming model.¹⁷ The clinical value of this prosthesis, however, has not been determined. Therefore, we conducted a study to describe the intermediate-term clinical and radiographic outcomes of TSAs that use a novel hybrid glenoid component.

Materials and Methods

This study was approved (protocol AAAD3473) by the Institutional Review Board of Columbia University and was conducted in compliance with Health Insurance Portability and Accountability Act (HIPAA) regulations.

Patient Selection

At Columbia University Medical Center, Dr. Bigliani performed 196 TSAs with a hybrid glenoid component (Bigliani-Flatow; Zimmer Biomet) in 169 patients between September 1998 and November 2007. All patients had received a diagnosis of primary glenohumeral arthritis as defined by Neer.¹⁸ Patients with previous surgery such as rotator cuff repair or subacromial decompression were included in our review, and patients with a nonprimary form of arthritis, such as rheumatoid, posttraumatic, or post-capsulorrhaphy arthritis, were excluded.

Operative Technique

For all surgeries, Dr. Bigliani performed a subscapularis tenotomy with regional anesthesia and a standard deltopectoral approach. A partial anterior capsulectomy was performed to increase the glenoid’s visibility. The inferior labrum was removed with a needle-tip bovie while the axillary nerve was being protected with a metal finger or narrow Darrach retractor. After reaming and trialing, the final glenoid component was cemented into place. Cement was placed only in the peg or keel holes and pressurized twice before final implantation. Of the 196 glenoid components, 168 (86%) were pegged and 28 (14%) keeled; in addition,190 of these components were all-polyethylene, whereas 6 had trabecular-metal backing. All glenoid components incorporated the hybrid design of dual radii of curvature. After the glenoid was cemented, the final humeral component was placed in 30° of retroversion. Whenever posterior wear was found, retroversion was reduced by 5° to 10°. The humeral prosthesis was cemented in cases (104/196, 53%) of poor bone quality or a large canal.

After surgery, the patient’s sling was fitted with an abduction pillow and a swathe, to be worn the first 24 hours, and the arm was passively ranged. Patients typically were discharged on postoperative day 2. Then, for 2 weeks, they followed an assisted passive range of motion (ROM) protocol, with limited external rotation, for promotion of subscapularis healing.

Clinical Outcomes

Dr. Bigliani assessed preoperative ROM in all planes. During initial evaluation, patients completed a questionnaire that consisted of the 36-Item Short Form Health Survey^19,20 (SF-36) and the American Shoulder and Elbow Surgeons²¹ (ASES) and Simple Shoulder Test²² (SST) surveys. Postoperative clinical data were collected from office follow-up visits, survey questionnaires, or both. Postoperative office data included ROM, subscapularis integrity testing (belly-press or lift-off), and any complications. Patients with <1 year of office follow-up were excluded. In addition, the same survey questionnaire that was used before surgery was mailed to all patients after surgery; then, for anyone who did not respond by mail, we attempted contact by telephone. Neer criteria were based on patients’ subjective assessment of each arm on a 3-point Likert scale (1 = very satisfied, 2 = satisfied, 3 = dissatisfied). Patients were also asked about any specific complications or revision operations since their index procedure.

Physical examination and office follow-up data were obtained for 129 patients (148/196 shoulders, 76% follow-up) at a mean of 3.7 years (range 1.0-10.2 years) after surgery. Surveys were completed by 117 patients (139/196 shoulders, 71% follow-up) at a mean of 5.1 years (range, 1.6-11.2 years) after surgery. Only 15 patients had neither 1 year of office follow-up nor a completed questionnaire. The remaining 154 patients (178/196 shoulders, 91% follow-up) had clinical follow-up with office, mail, or telephone questionnaire at a mean of 4.8 years (range, 1.0-11.2 years) after surgery. This cohort of patients was used to determine rates of surgical revisions, subscapularis tears, dislocations, and other complications.

Radiographic Outcomes

Patients were included in the radiographic analysis if they had a shoulder radiograph at least 1 year after surgery. One hundred nineteen patients (136/196 shoulders, 69% follow-up) had radiographic follow-up at a mean of 3.7 years (range, 1.0-9.4 years) after surgery.

Statistical Analysis

Statistical analysis was performed with Stata Version 10.0. Paired t tests were used to compare preoperative and postoperative numerical data, including ROM and survey scores. We calculated 95% confidence intervals (CIs) and set statistical significance at P < .05. For qualitative measures, the Fisher exact test was used. Survivorship analysis was performed according to the Kaplan-Meier method, with right-censored data for no event or missing data.²⁵

Results

Clinical Analysis of Demographics

In demographics, the clinical and radiographic patient subgroups were similar to each other and to the overall study population (Table 2). Of 196 patients overall, 16 (8%) had a concomitant rotator cuff repair, and 27 (14%) underwent staged bilateral shoulder arthroplasties.

Clinical Analysis of ROM and Survey Scores

Operative shoulder ROM in forward elevation, external rotation at side, external rotation in abduction, and internal rotation all showed statistically significant (P < .001) improvement from before surgery to after surgery. Over 3.7 years, mean (SD) forward elevation improved from 107.3° (34.8°) to 159.0° (29.4°), external rotation at side improved from 20.4° (16.7°) to 49.4° (11.3°), and external rotation in abduction improved from 53.7° (24.3°) to 84.7° (9.1°). Internal rotation improved from a mean (SD) vertebral level of S1 (6.0 levels) to T9 (3.7 levels).

All validated survey scores also showed statistically significant (P < .001) improvement from before surgery to after surgery. Over 5.1 years, mean (SD) SF-36 scores improved from 64.9 (13.4) to 73.6 (17.1), ASES scores improved from 41.1 (22.5) to 82.7 (17.7), SST scores improved from 3.9 (2.8) to 9.7 (2.2), and visual analog scale pain scores improved from 5.6 (3.2) to 1.4 (2.1). Of 139 patients with follow-up, 130 (93.5%) were either satisfied or very satisfied with their TSA, and only 119 (86%) were either satisfied or very satisfied with the nonoperative shoulder.

Clinical Analysis of Postoperative Complications

Of the 178 shoulders evaluated for complications, 3 (1.7%) underwent revision surgery. Mean time to revision was 2.3 years (range, 1.5-3.9 years). Two revisions involved the glenoid component, and the third involved the humerus. In one of the glenoid cases, a 77-year-old woman fell and sustained a fracture at the base of the trabecular metal glenoid pegs; her component was revised to an all-polyethylene component, and she had no further complications. In the other glenoid case, a 73-year-old man’s all-polyethylene component loosened after 2 years and was revised to a trabecular metal implant, which loosened as well and was later converted to a hemiarthroplasty. In the humeral case, a 33-year-old man had his 4-year-old index TSA revised to a cemented stem and had no further complications.

Table 4 compares the clinical and radiographic outcomes of patients who required subscapularis repair, capsular shift, or implant revision with the outcomes of all other study patients, and Figure 3 shows Kaplan-Meier survivorship.

Postoperative Radiographic Analysis

Glenoid Component. At a mean of 3.7 years (minimum, 1 year) after surgery, 86 (63%) of 136 radiographically evaluated shoulders showed no glenoid lucencies; the other 50 (37%) showed ≥1 lucency. Of the 136 shoulders, 33 (24%) had a Lazarus score of 1, 15 (11%) had a score of 2, and only 2 (2%) had a score of 3. None of the shoulders had a score of 4 or 5.

Humeral Component. Of the 136 shoulders, 91 (67%) showed no lucencies in any of the 8 humeral stem zones; the other 45 (33%) showed 1 to 3 lucencies. Thirty (22%) of the 136 shoulders had 1 stem lucency zone, 8 (6%) had 2, and 3 (2%) had 3. None of the shoulders had >3 periprosthetic zones with lucent lines.

Discussion

In this article, we describe a hybrid glenoid TSA component with dual radii of curvature. Its central portion is congruent with the humeral head, and its peripheral portion is noncongruent and larger. The most significant finding of our study is the low rate (1.1%) of glenoid component revision 4.8 years after surgery. This rate is the lowest that has been reported in a study of ≥100 patients. Overall implant survival appeared as an almost flat Kaplan-Meir curve. We attribute this low revision rate to improved biomechanics with the hybrid glenoid design. 

Symptomatic glenoid component loosening is the most common TSA complication.^1,26-28 In a review of 73 Neer TSAs, Cofield7 found glenoid radiolucencies in 71% of patients 3.8 years after surgery. Radiographic evidence of loosening, defined as component migration, or tilt, or a circumferential lucency 1.5 mm thick, was present in another 11% of patients, and 4.1% developed symptomatic loosening that required glenoid revision. In a study with 12.2-year follow-up, Torchia and colleagues³ found rates of 84% for glenoid radiolucencies, 44% for radiographic loosening, and 5.6% for symptomatic loosening that required revision. In a systematic review of studies with follow-up of ≥10 years, Bohsali and colleagues²⁷ found similar lucency and radiographic loosening rates and a 7% glenoid revision rate. These data suggest glenoid radiolucencies may progress to component loosening.

Degree of joint congruence is a key factor in glenoid loosening. Neer’s congruent design increases the contact area with concentric loading and reduces glenohumeral translation, which leads to reduced polyethylene wear and improved joint stability. In extreme arm positions, however, humeral head subluxation results in edge loading and a glenoid rocking-horse effect.^{9-13,17,29-31} Conversely, nonconforming implants allow increased glenohumeral translation without edge loading,¹⁴ though they also reduce the relative glenohumeral contact area and thus transmit more contact stress to the glenoid.^16,17 A hybrid glenoid component with central conforming and peripheral nonconforming zones may reduce the rocking-horse effect while maximizing ROM and joint stability. Wang and colleagues32 studied the biomechanical properties of this glenoid design and found that the addition of a central conforming region did not increase edge loading.

Additional results from our study support the efficacy of a hybrid glenoid component. Patients’ clinical outcomes improved significantly. At 5.1 years after surgery, 93.5% of patients were satisfied or very satisfied with their procedure and reported less satisfaction (86%) with the nonoperative shoulder. Also significant was the reduced number of radiolucencies. At 3.7 years after surgery, the overall percentage of shoulders with ≥1 glenoid radiolucency was 37%, considerably lower than the 82% reported by Cofield7 and the rates in more recent studies.^3,16,33-36 Of the 178 shoulders in our study, 10 (5.6%) had subscapularis tears, and 6 (3.4%) of 178 had these tears surgically repaired. This 3.4% compares favorably with the 5.9% (of 119 patients) found by Miller and colleagues37 28 months after surgery. Of our 178 shoulders, 27 (15.2%) had clinically significant postoperative complications; 18 (10.1%) of the 178 had these complications surgically treated, and 9 (5.1%) had them managed nonoperatively. Bohsali and colleagues²⁷ systematically reviewed 33 TSA studies and found a slightly higher complication rate (16.3%) 5.3 years after surgery. Furthermore, in our study, the 11 patients who underwent revision, capsular shift, or subscapularis repair had final outcomes comparable to those of the rest of our study population.

Our study had several potential weaknesses. First, its minimum clinical and radiographic follow-up was 1 year, whereas most long-term TSA series set a minimum of 2 years. We used 1 year because this was the first clinical study of the hybrid glenoid component design, and we wanted to maximize its sample size by reporting on intermediate-length outcomes. Even so, 93% (166/178) of our clinical patients and 83% (113/136) of our radiographic patients have had ≥2 years of follow-up, and we continue to follow all study patients for long-term outcomes. Another weakness of the study was its lack of a uniform group of patients with all the office, survey, complications, and radiographic data. Our retrospective study design made it difficult to obtain such a group without significantly reducing the sample size, so we divided patients into 4 data groups. A third potential weakness was the study’s variable method for collecting complications data. Rates of complications in the 178 shoulders were calculated from either office evaluation or patient self-report by mail or telephone. This data collection method is subject to recall bias, but mail and telephone contact was needed so the study would capture the large number of patients who had traveled to our institution for their surgery or had since moved away. Fourth, belly-press and lift-off tests were used in part to assess subscapularis function, but recent literature suggests post-TSA subscapularis assessment can be unreliable.³⁸ These tests may be positive in up to two-thirds of patients after 2 years.³⁹ Fifth, the generalizability of our findings to diagnoses such as rheumatoid and posttraumatic arthritis is limited. We had to restrict the study to patients with primary glenohumeral arthritis in order to minimize confounders.

This study’s main strength is its description of the clinical and radiographic outcomes of using a single prosthetic system in operations performed by a single surgeon in a large number of patients. This was the first and largest study evaluating the clinical and radiographic outcomes of this hybrid glenoid implant. Excluding patients with nonprimary arthritis allowed us to minimize potential confounding factors that affect patient outcomes. In conclusion, our study results showed the favorable clinical and radiographic outcomes of TSAs that have a hybrid glenoid component with dual radii of curvature. At a mean of 3.7 years after surgery, 63% of patients had no glenoid lucencies, and, at a mean of 4.8 years, only 1.7% of patients required revision. We continue to follow these patients to obtain long-term results of this innovative prosthesis.

Take-Home Points

• The authors have developed a total shoulder glenoid prosthesis that conforms with the humeral head in its center and is nonconforming on its peripheral edge.
• All clinical survey and range of motion parameters demonstrated statistically significant improvements at final follow-up.
• Only 3 shoulders (1.7%) required revision surgery.
• Eighty-six (63%) of 136 shoulders demonstrated no radiographic evidence of glenoid loosening.
• This is the first and largest study that evaluates the clinical and radiographic outcomes of this hybrid shoulder prosthesis.

Fixation of the glenoid component is the limiting factor in modern total shoulder arthroplasty (TSA). Glenoid loosening, the most common long-term complication, necessitates revision in up to 12% of patients.^1-4 By contrast, humeral component loosening is relatively uncommon, affecting as few as 0.34% of patients.⁵ Multiple long-term studies have found consistently high rates (45%-93%) of radiolucencies around the glenoid component.^3,6,7 Although their clinical significance has been debated, radiolucencies around the glenoid component raise concern about progressive loss of fixation.

Since TSA was introduced in the 1970s, complications with the glenoid component have been addressed with 2 different designs: conforming (congruent) and nonconforming. In a congruent articulation, the radii of curvature of the glenoid and humeral head components are identical, whereas they differ in a nonconforming model. Joint conformity is inversely related to glenohumeral translation.⁸ Neer’s original TSA was made congruent in order to limit translation and maximize the contact area. However, this design results in edge loading and a so-called rocking-horse phenomenon, which may lead to glenoid loosening.^9-13 Surgeons therefore have increasingly turned to nonconforming implants. In the nonconforming design, the radius of curvature of the humeral head is smaller than that of the glenoid. Although this design may reduce edge loading,¹⁴ it allows more translation and reduces the relative contact area of the glenohumeral joint. As a result, more contact stress is transmitted to the glenoid component, leading to polyethylene deformation and wear.^15,16

Dual radii of curvature are designed to augment joint stability without increasing component wear. Biomechanical data have indicated that edge loading is not increased by having a central conforming region added to a nonconforming model.¹⁷ The clinical value of this prosthesis, however, has not been determined. Therefore, we conducted a study to describe the intermediate-term clinical and radiographic outcomes of TSAs that use a novel hybrid glenoid component.

Materials and Methods

This study was approved (protocol AAAD3473) by the Institutional Review Board of Columbia University and was conducted in compliance with Health Insurance Portability and Accountability Act (HIPAA) regulations.

Patient Selection

At Columbia University Medical Center, Dr. Bigliani performed 196 TSAs with a hybrid glenoid component (Bigliani-Flatow; Zimmer Biomet) in 169 patients between September 1998 and November 2007. All patients had received a diagnosis of primary glenohumeral arthritis as defined by Neer.¹⁸ Patients with previous surgery such as rotator cuff repair or subacromial decompression were included in our review, and patients with a nonprimary form of arthritis, such as rheumatoid, posttraumatic, or post-capsulorrhaphy arthritis, were excluded.

Operative Technique

For all surgeries, Dr. Bigliani performed a subscapularis tenotomy with regional anesthesia and a standard deltopectoral approach. A partial anterior capsulectomy was performed to increase the glenoid’s visibility. The inferior labrum was removed with a needle-tip bovie while the axillary nerve was being protected with a metal finger or narrow Darrach retractor. After reaming and trialing, the final glenoid component was cemented into place. Cement was placed only in the peg or keel holes and pressurized twice before final implantation. Of the 196 glenoid components, 168 (86%) were pegged and 28 (14%) keeled; in addition,190 of these components were all-polyethylene, whereas 6 had trabecular-metal backing. All glenoid components incorporated the hybrid design of dual radii of curvature. After the glenoid was cemented, the final humeral component was placed in 30° of retroversion. Whenever posterior wear was found, retroversion was reduced by 5° to 10°. The humeral prosthesis was cemented in cases (104/196, 53%) of poor bone quality or a large canal.

After surgery, the patient’s sling was fitted with an abduction pillow and a swathe, to be worn the first 24 hours, and the arm was passively ranged. Patients typically were discharged on postoperative day 2. Then, for 2 weeks, they followed an assisted passive range of motion (ROM) protocol, with limited external rotation, for promotion of subscapularis healing.

Clinical Outcomes

Dr. Bigliani assessed preoperative ROM in all planes. During initial evaluation, patients completed a questionnaire that consisted of the 36-Item Short Form Health Survey^19,20 (SF-36) and the American Shoulder and Elbow Surgeons²¹ (ASES) and Simple Shoulder Test²² (SST) surveys. Postoperative clinical data were collected from office follow-up visits, survey questionnaires, or both. Postoperative office data included ROM, subscapularis integrity testing (belly-press or lift-off), and any complications. Patients with <1 year of office follow-up were excluded. In addition, the same survey questionnaire that was used before surgery was mailed to all patients after surgery; then, for anyone who did not respond by mail, we attempted contact by telephone. Neer criteria were based on patients’ subjective assessment of each arm on a 3-point Likert scale (1 = very satisfied, 2 = satisfied, 3 = dissatisfied). Patients were also asked about any specific complications or revision operations since their index procedure.

Physical examination and office follow-up data were obtained for 129 patients (148/196 shoulders, 76% follow-up) at a mean of 3.7 years (range 1.0-10.2 years) after surgery. Surveys were completed by 117 patients (139/196 shoulders, 71% follow-up) at a mean of 5.1 years (range, 1.6-11.2 years) after surgery. Only 15 patients had neither 1 year of office follow-up nor a completed questionnaire. The remaining 154 patients (178/196 shoulders, 91% follow-up) had clinical follow-up with office, mail, or telephone questionnaire at a mean of 4.8 years (range, 1.0-11.2 years) after surgery. This cohort of patients was used to determine rates of surgical revisions, subscapularis tears, dislocations, and other complications.

Radiographic Outcomes

Patients were included in the radiographic analysis if they had a shoulder radiograph at least 1 year after surgery. One hundred nineteen patients (136/196 shoulders, 69% follow-up) had radiographic follow-up at a mean of 3.7 years (range, 1.0-9.4 years) after surgery.

Statistical Analysis

Statistical analysis was performed with Stata Version 10.0. Paired t tests were used to compare preoperative and postoperative numerical data, including ROM and survey scores. We calculated 95% confidence intervals (CIs) and set statistical significance at P < .05. For qualitative measures, the Fisher exact test was used. Survivorship analysis was performed according to the Kaplan-Meier method, with right-censored data for no event or missing data.²⁵

Results

Clinical Analysis of Demographics

In demographics, the clinical and radiographic patient subgroups were similar to each other and to the overall study population (Table 2). Of 196 patients overall, 16 (8%) had a concomitant rotator cuff repair, and 27 (14%) underwent staged bilateral shoulder arthroplasties.

Clinical Analysis of ROM and Survey Scores

Operative shoulder ROM in forward elevation, external rotation at side, external rotation in abduction, and internal rotation all showed statistically significant (P < .001) improvement from before surgery to after surgery. Over 3.7 years, mean (SD) forward elevation improved from 107.3° (34.8°) to 159.0° (29.4°), external rotation at side improved from 20.4° (16.7°) to 49.4° (11.3°), and external rotation in abduction improved from 53.7° (24.3°) to 84.7° (9.1°). Internal rotation improved from a mean (SD) vertebral level of S1 (6.0 levels) to T9 (3.7 levels).

All validated survey scores also showed statistically significant (P < .001) improvement from before surgery to after surgery. Over 5.1 years, mean (SD) SF-36 scores improved from 64.9 (13.4) to 73.6 (17.1), ASES scores improved from 41.1 (22.5) to 82.7 (17.7), SST scores improved from 3.9 (2.8) to 9.7 (2.2), and visual analog scale pain scores improved from 5.6 (3.2) to 1.4 (2.1). Of 139 patients with follow-up, 130 (93.5%) were either satisfied or very satisfied with their TSA, and only 119 (86%) were either satisfied or very satisfied with the nonoperative shoulder.

Clinical Analysis of Postoperative Complications

Of the 178 shoulders evaluated for complications, 3 (1.7%) underwent revision surgery. Mean time to revision was 2.3 years (range, 1.5-3.9 years). Two revisions involved the glenoid component, and the third involved the humerus. In one of the glenoid cases, a 77-year-old woman fell and sustained a fracture at the base of the trabecular metal glenoid pegs; her component was revised to an all-polyethylene component, and she had no further complications. In the other glenoid case, a 73-year-old man’s all-polyethylene component loosened after 2 years and was revised to a trabecular metal implant, which loosened as well and was later converted to a hemiarthroplasty. In the humeral case, a 33-year-old man had his 4-year-old index TSA revised to a cemented stem and had no further complications.

Table 4 compares the clinical and radiographic outcomes of patients who required subscapularis repair, capsular shift, or implant revision with the outcomes of all other study patients, and Figure 3 shows Kaplan-Meier survivorship.

Postoperative Radiographic Analysis

Glenoid Component. At a mean of 3.7 years (minimum, 1 year) after surgery, 86 (63%) of 136 radiographically evaluated shoulders showed no glenoid lucencies; the other 50 (37%) showed ≥1 lucency. Of the 136 shoulders, 33 (24%) had a Lazarus score of 1, 15 (11%) had a score of 2, and only 2 (2%) had a score of 3. None of the shoulders had a score of 4 or 5.

Humeral Component. Of the 136 shoulders, 91 (67%) showed no lucencies in any of the 8 humeral stem zones; the other 45 (33%) showed 1 to 3 lucencies. Thirty (22%) of the 136 shoulders had 1 stem lucency zone, 8 (6%) had 2, and 3 (2%) had 3. None of the shoulders had >3 periprosthetic zones with lucent lines.

Discussion

In this article, we describe a hybrid glenoid TSA component with dual radii of curvature. Its central portion is congruent with the humeral head, and its peripheral portion is noncongruent and larger. The most significant finding of our study is the low rate (1.1%) of glenoid component revision 4.8 years after surgery. This rate is the lowest that has been reported in a study of ≥100 patients. Overall implant survival appeared as an almost flat Kaplan-Meir curve. We attribute this low revision rate to improved biomechanics with the hybrid glenoid design. 

Symptomatic glenoid component loosening is the most common TSA complication.^1,26-28 In a review of 73 Neer TSAs, Cofield7 found glenoid radiolucencies in 71% of patients 3.8 years after surgery. Radiographic evidence of loosening, defined as component migration, or tilt, or a circumferential lucency 1.5 mm thick, was present in another 11% of patients, and 4.1% developed symptomatic loosening that required glenoid revision. In a study with 12.2-year follow-up, Torchia and colleagues³ found rates of 84% for glenoid radiolucencies, 44% for radiographic loosening, and 5.6% for symptomatic loosening that required revision. In a systematic review of studies with follow-up of ≥10 years, Bohsali and colleagues²⁷ found similar lucency and radiographic loosening rates and a 7% glenoid revision rate. These data suggest glenoid radiolucencies may progress to component loosening.

Degree of joint congruence is a key factor in glenoid loosening. Neer’s congruent design increases the contact area with concentric loading and reduces glenohumeral translation, which leads to reduced polyethylene wear and improved joint stability. In extreme arm positions, however, humeral head subluxation results in edge loading and a glenoid rocking-horse effect.^{9-13,17,29-31} Conversely, nonconforming implants allow increased glenohumeral translation without edge loading,¹⁴ though they also reduce the relative glenohumeral contact area and thus transmit more contact stress to the glenoid.^16,17 A hybrid glenoid component with central conforming and peripheral nonconforming zones may reduce the rocking-horse effect while maximizing ROM and joint stability. Wang and colleagues32 studied the biomechanical properties of this glenoid design and found that the addition of a central conforming region did not increase edge loading.

Additional results from our study support the efficacy of a hybrid glenoid component. Patients’ clinical outcomes improved significantly. At 5.1 years after surgery, 93.5% of patients were satisfied or very satisfied with their procedure and reported less satisfaction (86%) with the nonoperative shoulder. Also significant was the reduced number of radiolucencies. At 3.7 years after surgery, the overall percentage of shoulders with ≥1 glenoid radiolucency was 37%, considerably lower than the 82% reported by Cofield7 and the rates in more recent studies.^3,16,33-36 Of the 178 shoulders in our study, 10 (5.6%) had subscapularis tears, and 6 (3.4%) of 178 had these tears surgically repaired. This 3.4% compares favorably with the 5.9% (of 119 patients) found by Miller and colleagues37 28 months after surgery. Of our 178 shoulders, 27 (15.2%) had clinically significant postoperative complications; 18 (10.1%) of the 178 had these complications surgically treated, and 9 (5.1%) had them managed nonoperatively. Bohsali and colleagues²⁷ systematically reviewed 33 TSA studies and found a slightly higher complication rate (16.3%) 5.3 years after surgery. Furthermore, in our study, the 11 patients who underwent revision, capsular shift, or subscapularis repair had final outcomes comparable to those of the rest of our study population.

Our study had several potential weaknesses. First, its minimum clinical and radiographic follow-up was 1 year, whereas most long-term TSA series set a minimum of 2 years. We used 1 year because this was the first clinical study of the hybrid glenoid component design, and we wanted to maximize its sample size by reporting on intermediate-length outcomes. Even so, 93% (166/178) of our clinical patients and 83% (113/136) of our radiographic patients have had ≥2 years of follow-up, and we continue to follow all study patients for long-term outcomes. Another weakness of the study was its lack of a uniform group of patients with all the office, survey, complications, and radiographic data. Our retrospective study design made it difficult to obtain such a group without significantly reducing the sample size, so we divided patients into 4 data groups. A third potential weakness was the study’s variable method for collecting complications data. Rates of complications in the 178 shoulders were calculated from either office evaluation or patient self-report by mail or telephone. This data collection method is subject to recall bias, but mail and telephone contact was needed so the study would capture the large number of patients who had traveled to our institution for their surgery or had since moved away. Fourth, belly-press and lift-off tests were used in part to assess subscapularis function, but recent literature suggests post-TSA subscapularis assessment can be unreliable.³⁸ These tests may be positive in up to two-thirds of patients after 2 years.³⁹ Fifth, the generalizability of our findings to diagnoses such as rheumatoid and posttraumatic arthritis is limited. We had to restrict the study to patients with primary glenohumeral arthritis in order to minimize confounders.

This study’s main strength is its description of the clinical and radiographic outcomes of using a single prosthetic system in operations performed by a single surgeon in a large number of patients. This was the first and largest study evaluating the clinical and radiographic outcomes of this hybrid glenoid implant. Excluding patients with nonprimary arthritis allowed us to minimize potential confounding factors that affect patient outcomes. In conclusion, our study results showed the favorable clinical and radiographic outcomes of TSAs that have a hybrid glenoid component with dual radii of curvature. At a mean of 3.7 years after surgery, 63% of patients had no glenoid lucencies, and, at a mean of 4.8 years, only 1.7% of patients required revision. We continue to follow these patients to obtain long-term results of this innovative prosthesis.

Take-Home Points

• PFA improved knee function and pain scores in patients with isolated patellofemoral arthritis.
• The majority (84.2%) of patients undergoing PFA were female.
• Regardless of age or gender, 72.2% of patients returned to their desired preoperative activity after PFA, and 52.8% returned at the same or higher level.
• The rate of conversion from PFA to TKA was 6.3%.
• PFA is an alternative to TKA in active patients with isolated patellofemoral arthritis.

Compared with total knee arthroplasty (TKA), single-compartment knee arthroplasty may provide better physiologic function, faster recovery, and higher rates of return to activities in patients with unicompartmental knee disease.^1-3 In 1955, McKeever⁴ introduced patellar arthroplasty for surgical management of isolated patellofemoral arthritis. In 1979, Lubinus⁵ improved on the technique and design by adding a femoral component. Since then, implants and techniques have been developed to effect better clinical outcomes. Patellofemoral arthroplasty (PFA) has many advantages over TKA in the treatment of patellofemoral arthritis. PFA is less invasive, requires shorter tourniquet times, has faster recovery, and spares the tibiofemoral compartment, leaving more native bone for potential conversion to TKA. Regarding activity and function, the resurfacing arthroplasty (vs TKA) allows maintenance of nearly normal knee kinematics.

Despite these advantages, the broader orthopedic surgery community has only cautiously accepted PFA. The procedure has high complication rates. Persistent instability, malalignment, wear, impingement, and tibiofemoral arthritis progression can occur after PFA.⁶ Although first-generation PFA prostheses often failed because of mechanical problems, loosening, maltracking, or instability,⁷ the most common indication for PFA revision has been, according to a recent large retrospective study,⁸ unexplained pain. More than 10 to 15 years after PFA, tibiofemoral arthritis may be the primary mechanism of failure.⁹ Nevertheless, compared with standard TKA for isolated patellofemoral arthritis, modern PFA does not have significantly different clinical outcomes, including complication and revision rates.⁶Numerous patient factors influence functional prognosis before and after knee arthroplasty, regardless of surgical technique and implant used. Age, comorbidities, athletic status, mental health, pain, functional limitations, excessive caution, “artificial joint”–related worries, and rehabilitation protocol all influence function.¹⁰ Return to activity and other quality-of-life indices are important aspects of postoperative patient satisfaction.

Methods

We conducted a retrospective cohort study to describe functional status after PFA for patellofemoral arthritis. We identified 48 consecutive PFAs (39 patients) performed by a team of 2 orthopedic surgeons (specialists in treating patellofemoral pathology) between 2009 and 2014.

Three validated patient-reported outcome measures (PROMs) were used to determine preoperative (baseline) and postoperative functional status: Kujala score, Lysholm score, and International Knee Documentation Committee (IKDC) score. The Kujala score is a measure of knee function specific to the patellofemoral joint; the Lysholm score focuses on activities related to the knee; and the IKDC score is a general measure of knee function. Charts were reviewed to extract patients’ clinical data, including preoperative outcome scores, medical history, physical examination data, intraoperative characteristics, and postoperative course. By telephone, patients answered questions about their postoperative clinical course and completed final follow-up questionnaires. They were also asked which sporting or fitness activity they had preferred before surgery and whether they were able to return to that activity after surgery.

Statistical analysis included the study population’s descriptive statistics. Means and SDs were reported for continuous variables, and frequencies and percentages were reported for categorical variables. Paired t tests were used to analyze changes in PROM scores. For comparison of differences between characteristics of patients who did and did not return to their previous activity level, independent-samples t tests were used for continuous variables. Chi-square tests or Fisher exact tests were used to compare discrete variables. Statistical significance was set at P ≤ .05. All analyses were performed with SPSS Version 22.0 (IBM).

Results

Discussion

Historically, the literature evaluating knee arthroplasty outcomes has focused on implant survivorship, pain relief, and patient satisfaction. Since the advent of partial knee arthroplasty options, more attention has been given to functional outcomes and return to activities after single-compartment knee resurfacing. TKA remains the gold standard by which newer, less invasive surgical options are measured. In a large prospective study, 97% of patients (age, >55 years) who had TKA for patellofemoral arthritis reported good or excellent clinical results, the majority being excellent.¹¹ Post-TKA functional status and activity levels may not be rated as highly. After TKA, many patients switch to lower impact sports or reduce or stop their participation in sports.¹² A small study of competitive adult tennis players found high levels of post-TKA satisfaction, ability to resume playing tennis, pain relief, and increased or continued enjoyment in playing.¹³ In a study of 355 patients (417 knees) who had underwent TKA, improvement in Knee Society function score showed a moderate correlation to an increase in weighted activity score (R = 0.362).¹⁴

Unicondylar knee arthroplasty (UKA) is becoming a popular treatment option for single-compartment tibiofemoral arthritis. A systematic review of 18 original studies of patients with knee osteoarthritis found that overall return to sports varied from 36% to 89% after TKA and from 75% to 100% after UKA.¹⁵ In another study, return-to-sports rates were similar for UKA (87%) and TKA (83%); the only significant difference was UKA patients returned quicker.¹⁶ The authors of a large meta-analysis conceded that significant heterogeneity of data prevented them from drawing definitive conclusions, but UKA patients seemed to return to low- and high-impact sports 2 weeks faster than their TKA counterparts.¹⁰ Overall, UKA and TKA patients (age, 51-71 years) had comparable return-to-sports rates at an average of 4 years after surgery.¹⁰ A smaller study corroborated faster return to sports for UKA over TKA patients and also found that, compared with TKA patients, UKA patients participated in sports more regularly and over a longer period.¹⁷ On the other hand, Walton and colleagues¹⁸ found similar return-to-sports rates but higher frequency of and satisfaction with sports participation in UKA over TKA patients.

A large retrospective study found no differences in rates of return to sports after TKA, UKA, patellar resurfacing, hip resurfacing, and total hip arthroplasty.¹⁹ Pain was the most common barrier to return. UKA patients who returned to sports tended to be younger than those who did not.²⁰ Naal and colleagues³ found that 95% of UKA patients returned to their activities—hiking, walking, cycling, and swimming being most common. Although 90.3% of patients said surgery maintained or improved their ability to participate in sports, participation in high-impact sports (eg, running) decreased after surgery.

Outcomes of PFA vary because of evolving patient selection, implant design, surgical technique, and return-to-activity expectations.^21,22 Most PFA outcome studies focus on implant survivorship, complication rates, and postoperative knee scores.^23-28 PFA studies focused on return to activities are limited. Kooijman and colleagues⁷ and Mertl and colleagues²⁹ reported good or excellent clinical results of PFA in 86% and 82% of patients, respectively. Neither study included a comprehensive analysis of postoperative functional status. Similarly, De Cloedt and colleagues³⁰ reported good PFA outcomes in 43% of patients with degenerative joint disease and in 83% of patients with instability. Specific activity status was not described. Dahm and colleagues³¹ and Farr and colleagues³² suggested postoperative pain resolution motivates some PFA patients not only to resume preoperative activities but to start participating in new, higher level activities after pain has subsided. However, the studies did not examine the characteristics of patients who returned to baseline activities and did not examine return-to-sports rates.

Study Strengths and Limitations

Our study focused on the PFA patient population of a surgical team of 2 fellowship-trained orthopedic surgeons (specialists in treating patellofemoral pathology). Although generalization of our findings to other surgeons and different implants may be limited, the study design standardized treatment in a way that makes these findings more reliable. The 100% follow-up strengthens these findings as well. Last, though the patient population was relatively small, it was consistent with or larger than the PFA patient groups studied previously.

Conclusion

In this study, PROM and pain scores were significantly improved after PFA. That almost 75% of patients returned to their preferred activities and >50% of patients returned at the same or a higher activity level provides useful information for preoperative discussions with patients who want to remain active after PFA. Prospective studies are needed to evaluate the longevity and durability of PFA, particularly in active patients.

Take-Home Points

• PFA improved knee function and pain scores in patients with isolated patellofemoral arthritis.
• The majority (84.2%) of patients undergoing PFA were female.
• Regardless of age or gender, 72.2% of patients returned to their desired preoperative activity after PFA, and 52.8% returned at the same or higher level.
• The rate of conversion from PFA to TKA was 6.3%.
• PFA is an alternative to TKA in active patients with isolated patellofemoral arthritis.

Compared with total knee arthroplasty (TKA), single-compartment knee arthroplasty may provide better physiologic function, faster recovery, and higher rates of return to activities in patients with unicompartmental knee disease.^1-3 In 1955, McKeever⁴ introduced patellar arthroplasty for surgical management of isolated patellofemoral arthritis. In 1979, Lubinus⁵ improved on the technique and design by adding a femoral component. Since then, implants and techniques have been developed to effect better clinical outcomes. Patellofemoral arthroplasty (PFA) has many advantages over TKA in the treatment of patellofemoral arthritis. PFA is less invasive, requires shorter tourniquet times, has faster recovery, and spares the tibiofemoral compartment, leaving more native bone for potential conversion to TKA. Regarding activity and function, the resurfacing arthroplasty (vs TKA) allows maintenance of nearly normal knee kinematics.

Despite these advantages, the broader orthopedic surgery community has only cautiously accepted PFA. The procedure has high complication rates. Persistent instability, malalignment, wear, impingement, and tibiofemoral arthritis progression can occur after PFA.⁶ Although first-generation PFA prostheses often failed because of mechanical problems, loosening, maltracking, or instability,⁷ the most common indication for PFA revision has been, according to a recent large retrospective study,⁸ unexplained pain. More than 10 to 15 years after PFA, tibiofemoral arthritis may be the primary mechanism of failure.⁹ Nevertheless, compared with standard TKA for isolated patellofemoral arthritis, modern PFA does not have significantly different clinical outcomes, including complication and revision rates.⁶Numerous patient factors influence functional prognosis before and after knee arthroplasty, regardless of surgical technique and implant used. Age, comorbidities, athletic status, mental health, pain, functional limitations, excessive caution, “artificial joint”–related worries, and rehabilitation protocol all influence function.¹⁰ Return to activity and other quality-of-life indices are important aspects of postoperative patient satisfaction.

Methods

We conducted a retrospective cohort study to describe functional status after PFA for patellofemoral arthritis. We identified 48 consecutive PFAs (39 patients) performed by a team of 2 orthopedic surgeons (specialists in treating patellofemoral pathology) between 2009 and 2014.

Three validated patient-reported outcome measures (PROMs) were used to determine preoperative (baseline) and postoperative functional status: Kujala score, Lysholm score, and International Knee Documentation Committee (IKDC) score. The Kujala score is a measure of knee function specific to the patellofemoral joint; the Lysholm score focuses on activities related to the knee; and the IKDC score is a general measure of knee function. Charts were reviewed to extract patients’ clinical data, including preoperative outcome scores, medical history, physical examination data, intraoperative characteristics, and postoperative course. By telephone, patients answered questions about their postoperative clinical course and completed final follow-up questionnaires. They were also asked which sporting or fitness activity they had preferred before surgery and whether they were able to return to that activity after surgery.

Statistical analysis included the study population’s descriptive statistics. Means and SDs were reported for continuous variables, and frequencies and percentages were reported for categorical variables. Paired t tests were used to analyze changes in PROM scores. For comparison of differences between characteristics of patients who did and did not return to their previous activity level, independent-samples t tests were used for continuous variables. Chi-square tests or Fisher exact tests were used to compare discrete variables. Statistical significance was set at P ≤ .05. All analyses were performed with SPSS Version 22.0 (IBM).

Results

Discussion

Historically, the literature evaluating knee arthroplasty outcomes has focused on implant survivorship, pain relief, and patient satisfaction. Since the advent of partial knee arthroplasty options, more attention has been given to functional outcomes and return to activities after single-compartment knee resurfacing. TKA remains the gold standard by which newer, less invasive surgical options are measured. In a large prospective study, 97% of patients (age, >55 years) who had TKA for patellofemoral arthritis reported good or excellent clinical results, the majority being excellent.¹¹ Post-TKA functional status and activity levels may not be rated as highly. After TKA, many patients switch to lower impact sports or reduce or stop their participation in sports.¹² A small study of competitive adult tennis players found high levels of post-TKA satisfaction, ability to resume playing tennis, pain relief, and increased or continued enjoyment in playing.¹³ In a study of 355 patients (417 knees) who had underwent TKA, improvement in Knee Society function score showed a moderate correlation to an increase in weighted activity score (R = 0.362).¹⁴

Unicondylar knee arthroplasty (UKA) is becoming a popular treatment option for single-compartment tibiofemoral arthritis. A systematic review of 18 original studies of patients with knee osteoarthritis found that overall return to sports varied from 36% to 89% after TKA and from 75% to 100% after UKA.¹⁵ In another study, return-to-sports rates were similar for UKA (87%) and TKA (83%); the only significant difference was UKA patients returned quicker.¹⁶ The authors of a large meta-analysis conceded that significant heterogeneity of data prevented them from drawing definitive conclusions, but UKA patients seemed to return to low- and high-impact sports 2 weeks faster than their TKA counterparts.¹⁰ Overall, UKA and TKA patients (age, 51-71 years) had comparable return-to-sports rates at an average of 4 years after surgery.¹⁰ A smaller study corroborated faster return to sports for UKA over TKA patients and also found that, compared with TKA patients, UKA patients participated in sports more regularly and over a longer period.¹⁷ On the other hand, Walton and colleagues¹⁸ found similar return-to-sports rates but higher frequency of and satisfaction with sports participation in UKA over TKA patients.

A large retrospective study found no differences in rates of return to sports after TKA, UKA, patellar resurfacing, hip resurfacing, and total hip arthroplasty.¹⁹ Pain was the most common barrier to return. UKA patients who returned to sports tended to be younger than those who did not.²⁰ Naal and colleagues³ found that 95% of UKA patients returned to their activities—hiking, walking, cycling, and swimming being most common. Although 90.3% of patients said surgery maintained or improved their ability to participate in sports, participation in high-impact sports (eg, running) decreased after surgery.

Outcomes of PFA vary because of evolving patient selection, implant design, surgical technique, and return-to-activity expectations.^21,22 Most PFA outcome studies focus on implant survivorship, complication rates, and postoperative knee scores.^23-28 PFA studies focused on return to activities are limited. Kooijman and colleagues⁷ and Mertl and colleagues²⁹ reported good or excellent clinical results of PFA in 86% and 82% of patients, respectively. Neither study included a comprehensive analysis of postoperative functional status. Similarly, De Cloedt and colleagues³⁰ reported good PFA outcomes in 43% of patients with degenerative joint disease and in 83% of patients with instability. Specific activity status was not described. Dahm and colleagues³¹ and Farr and colleagues³² suggested postoperative pain resolution motivates some PFA patients not only to resume preoperative activities but to start participating in new, higher level activities after pain has subsided. However, the studies did not examine the characteristics of patients who returned to baseline activities and did not examine return-to-sports rates.

Study Strengths and Limitations

Our study focused on the PFA patient population of a surgical team of 2 fellowship-trained orthopedic surgeons (specialists in treating patellofemoral pathology). Although generalization of our findings to other surgeons and different implants may be limited, the study design standardized treatment in a way that makes these findings more reliable. The 100% follow-up strengthens these findings as well. Last, though the patient population was relatively small, it was consistent with or larger than the PFA patient groups studied previously.

Conclusion

In this study, PROM and pain scores were significantly improved after PFA. That almost 75% of patients returned to their preferred activities and >50% of patients returned at the same or a higher activity level provides useful information for preoperative discussions with patients who want to remain active after PFA. Prospective studies are needed to evaluate the longevity and durability of PFA, particularly in active patients.

Take-Home Points

• PFA improved knee function and pain scores in patients with isolated patellofemoral arthritis.
• The majority (84.2%) of patients undergoing PFA were female.
• Regardless of age or gender, 72.2% of patients returned to their desired preoperative activity after PFA, and 52.8% returned at the same or higher level.
• The rate of conversion from PFA to TKA was 6.3%.
• PFA is an alternative to TKA in active patients with isolated patellofemoral arthritis.

Compared with total knee arthroplasty (TKA), single-compartment knee arthroplasty may provide better physiologic function, faster recovery, and higher rates of return to activities in patients with unicompartmental knee disease.^1-3 In 1955, McKeever⁴ introduced patellar arthroplasty for surgical management of isolated patellofemoral arthritis. In 1979, Lubinus⁵ improved on the technique and design by adding a femoral component. Since then, implants and techniques have been developed to effect better clinical outcomes. Patellofemoral arthroplasty (PFA) has many advantages over TKA in the treatment of patellofemoral arthritis. PFA is less invasive, requires shorter tourniquet times, has faster recovery, and spares the tibiofemoral compartment, leaving more native bone for potential conversion to TKA. Regarding activity and function, the resurfacing arthroplasty (vs TKA) allows maintenance of nearly normal knee kinematics.

Despite these advantages, the broader orthopedic surgery community has only cautiously accepted PFA. The procedure has high complication rates. Persistent instability, malalignment, wear, impingement, and tibiofemoral arthritis progression can occur after PFA.⁶ Although first-generation PFA prostheses often failed because of mechanical problems, loosening, maltracking, or instability,⁷ the most common indication for PFA revision has been, according to a recent large retrospective study,⁸ unexplained pain. More than 10 to 15 years after PFA, tibiofemoral arthritis may be the primary mechanism of failure.⁹ Nevertheless, compared with standard TKA for isolated patellofemoral arthritis, modern PFA does not have significantly different clinical outcomes, including complication and revision rates.⁶Numerous patient factors influence functional prognosis before and after knee arthroplasty, regardless of surgical technique and implant used. Age, comorbidities, athletic status, mental health, pain, functional limitations, excessive caution, “artificial joint”–related worries, and rehabilitation protocol all influence function.¹⁰ Return to activity and other quality-of-life indices are important aspects of postoperative patient satisfaction.

Methods

We conducted a retrospective cohort study to describe functional status after PFA for patellofemoral arthritis. We identified 48 consecutive PFAs (39 patients) performed by a team of 2 orthopedic surgeons (specialists in treating patellofemoral pathology) between 2009 and 2014.

Three validated patient-reported outcome measures (PROMs) were used to determine preoperative (baseline) and postoperative functional status: Kujala score, Lysholm score, and International Knee Documentation Committee (IKDC) score. The Kujala score is a measure of knee function specific to the patellofemoral joint; the Lysholm score focuses on activities related to the knee; and the IKDC score is a general measure of knee function. Charts were reviewed to extract patients’ clinical data, including preoperative outcome scores, medical history, physical examination data, intraoperative characteristics, and postoperative course. By telephone, patients answered questions about their postoperative clinical course and completed final follow-up questionnaires. They were also asked which sporting or fitness activity they had preferred before surgery and whether they were able to return to that activity after surgery.

Statistical analysis included the study population’s descriptive statistics. Means and SDs were reported for continuous variables, and frequencies and percentages were reported for categorical variables. Paired t tests were used to analyze changes in PROM scores. For comparison of differences between characteristics of patients who did and did not return to their previous activity level, independent-samples t tests were used for continuous variables. Chi-square tests or Fisher exact tests were used to compare discrete variables. Statistical significance was set at P ≤ .05. All analyses were performed with SPSS Version 22.0 (IBM).

Results

Discussion

Historically, the literature evaluating knee arthroplasty outcomes has focused on implant survivorship, pain relief, and patient satisfaction. Since the advent of partial knee arthroplasty options, more attention has been given to functional outcomes and return to activities after single-compartment knee resurfacing. TKA remains the gold standard by which newer, less invasive surgical options are measured. In a large prospective study, 97% of patients (age, >55 years) who had TKA for patellofemoral arthritis reported good or excellent clinical results, the majority being excellent.¹¹ Post-TKA functional status and activity levels may not be rated as highly. After TKA, many patients switch to lower impact sports or reduce or stop their participation in sports.¹² A small study of competitive adult tennis players found high levels of post-TKA satisfaction, ability to resume playing tennis, pain relief, and increased or continued enjoyment in playing.¹³ In a study of 355 patients (417 knees) who had underwent TKA, improvement in Knee Society function score showed a moderate correlation to an increase in weighted activity score (R = 0.362).¹⁴

Unicondylar knee arthroplasty (UKA) is becoming a popular treatment option for single-compartment tibiofemoral arthritis. A systematic review of 18 original studies of patients with knee osteoarthritis found that overall return to sports varied from 36% to 89% after TKA and from 75% to 100% after UKA.¹⁵ In another study, return-to-sports rates were similar for UKA (87%) and TKA (83%); the only significant difference was UKA patients returned quicker.¹⁶ The authors of a large meta-analysis conceded that significant heterogeneity of data prevented them from drawing definitive conclusions, but UKA patients seemed to return to low- and high-impact sports 2 weeks faster than their TKA counterparts.¹⁰ Overall, UKA and TKA patients (age, 51-71 years) had comparable return-to-sports rates at an average of 4 years after surgery.¹⁰ A smaller study corroborated faster return to sports for UKA over TKA patients and also found that, compared with TKA patients, UKA patients participated in sports more regularly and over a longer period.¹⁷ On the other hand, Walton and colleagues¹⁸ found similar return-to-sports rates but higher frequency of and satisfaction with sports participation in UKA over TKA patients.

A large retrospective study found no differences in rates of return to sports after TKA, UKA, patellar resurfacing, hip resurfacing, and total hip arthroplasty.¹⁹ Pain was the most common barrier to return. UKA patients who returned to sports tended to be younger than those who did not.²⁰ Naal and colleagues³ found that 95% of UKA patients returned to their activities—hiking, walking, cycling, and swimming being most common. Although 90.3% of patients said surgery maintained or improved their ability to participate in sports, participation in high-impact sports (eg, running) decreased after surgery.

Outcomes of PFA vary because of evolving patient selection, implant design, surgical technique, and return-to-activity expectations.^21,22 Most PFA outcome studies focus on implant survivorship, complication rates, and postoperative knee scores.^23-28 PFA studies focused on return to activities are limited. Kooijman and colleagues⁷ and Mertl and colleagues²⁹ reported good or excellent clinical results of PFA in 86% and 82% of patients, respectively. Neither study included a comprehensive analysis of postoperative functional status. Similarly, De Cloedt and colleagues³⁰ reported good PFA outcomes in 43% of patients with degenerative joint disease and in 83% of patients with instability. Specific activity status was not described. Dahm and colleagues³¹ and Farr and colleagues³² suggested postoperative pain resolution motivates some PFA patients not only to resume preoperative activities but to start participating in new, higher level activities after pain has subsided. However, the studies did not examine the characteristics of patients who returned to baseline activities and did not examine return-to-sports rates.

Study Strengths and Limitations

Our study focused on the PFA patient population of a surgical team of 2 fellowship-trained orthopedic surgeons (specialists in treating patellofemoral pathology). Although generalization of our findings to other surgeons and different implants may be limited, the study design standardized treatment in a way that makes these findings more reliable. The 100% follow-up strengthens these findings as well. Last, though the patient population was relatively small, it was consistent with or larger than the PFA patient groups studied previously.

Conclusion

In this study, PROM and pain scores were significantly improved after PFA. That almost 75% of patients returned to their preferred activities and >50% of patients returned at the same or a higher activity level provides useful information for preoperative discussions with patients who want to remain active after PFA. Prospective studies are needed to evaluate the longevity and durability of PFA, particularly in active patients.

An environmental pathogen, Mycobacterium marinum can cause cutaneous infection when traumatized skin is exposed to fresh, brackish, or salt water. Fishing, aquarium cleaning, and aquatic recreational activities are risk factors for infection.^1,2 Diagnosis often is delayed and is made several weeks or even months after initial symptoms appear.³ Due to the protracted clinical course, patients may not recall the initial exposure, contributing to the delay in diagnosis and initiation of appropriate treatment. It is not uncommon for patients with M marinum infection to be initially treated with antibiotics or antifungal drugs.

We present a review of 5 patients who were diagnosed with M marinum infection at our institution between January 2003 and March 2013.

Methods

This study was conducted at Henry Ford Hospital, a 900-bed tertiary care center in Detroit, Michigan. Patients who had cultures positive for M marinum between January 2003 and March 2013 were identified using the institution’s laboratory database. Medical records were reviewed, and relevant demographic, epidemiologic, and clinical data, including initial clinical presentation, alternative diagnoses, time between initial presentation and definitive diagnosis, and specific treatment, were recorded.

Results

We identified 5 patients who were diagnosed with culture-confirmed M marinum skin infections during the study period: 3 men and 2 women aged 43 to 72 years (Table 1). Two patients had diabetes mellitus and 1 had hepatitis C virus. None had classic immunosuppression. On repeated questioning after the diagnosis was established, all 5 patients reported that they kept a home aquarium, and all recalled mild trauma to the hand prior to the onset of symptoms; however, none of the patients initially linked the minor skin injury to the subsequent infection.

All 5 patients initially presented with erythema and swelling at the site of the injury, which evolved into inflammatory nodules that progressed proximally up to the arm despite empiric treatment with antibiotics active against streptococci and staphylococci (Figures 1 and 2). Three patients also received empiric antifungal therapy due to suspicion of sporotrichosis.

Skin biopsies were performed on 4 patients, and incision and drainage of purulent material was performed on the fifth patient. Histopathologic examination revealed granulomatous inflammation in 3 patients. Stains for acid-fast bacilli were positive in all 5 patients. Definitive diagnosis of the organism was confirmed by growth of M marinum within 11 to 40 days from the tissue in 4 patients and purulent material in the fifth patient. Susceptibility testing was performed on only 1 of the 5 isolates and showed that the organism was susceptible to amikacin, clarithromycin, doxycycline, ethambutol, rifampin, and trimethoprim-sulfamethoxazole (TMP-SMX).

The mean time from initial presentation to initiation of appropriate therapy for M marinum infection was 91 days (range, 21–245 days). Several different treatment regimens were used. All patients received either doxycycline or minocycline with or without a macrolide. Two also received other agents (TMP-SMX or ethambutol). Treatment duration varied from 2 to 6 months in 4 patients, and all 4 had complete resolution of the lesions; 1 patient was lost to follow-up.

Comment

Diagnosing the Infection
Diagnosis of M marinum infection remains problematic. In the 5 patients included in this study, the time between initial onset of symptoms and diagnosis of M marinum infection was delayed, as has been noted in other reports.^4-7 Delays as long as 2 years before the diagnosis is made have been described.⁷ The clinical presentation of cutaneous infection with M marinum varies, which may delay diagnosis. Nodular lymphangitis is classic, but papules, pustules, ulcers, inflammatory plaques, and single nodules also can occur.^1,2 Lymphadenopathy may or may not be present.^4,8,9 The differential diagnosis is broad and includes infection by other nontuberculous mycobacteria such as Mycobacterium chelonae; Mycobacterium fortuitum; Nocardia species, especially Nocardia brasiliensis; Francisella tularensis; Sporothrix schenckii; and Leishmania species. It is not surprising that 4 patients in our study were initially treated for a gram-positive bacterial infection and 3 were treated for a fungal infection before the diagnosis of M marinum was made. Distinctive features that may help to differentiate these infections are summarized in Table 2.

We found that the main cause of delayed diagnosis was the failure of physicians to obtain a thorough history regarding patients’ recreational activities and animal exposure. Patients often do not associate a remote aquatic exposure with their symptoms and will not volunteer this information unless directly asked.^2,10 It was only after repeated questioning in all of these patients that they recounted prior trauma to the involved hand related to the aquarium.

Biopsy and Culture
Histopathologic examination of material from a biopsied lesion can give an early clue that a mycobacterial infection might be involved. Biopsy can reveal either noncaseating or necrotizing granulomas that have larger numbers of neutrophils in addition to lymphocytes and macrophages. Giant cells often are noted.^5,9,11 Organisms can be seen with the use of a tissue acid-fast stain, but species cannot be differentiated by acid-fast staining.¹² However, the sensitivity of acid-fast stains on biopsy material is low.^3,13,14

Culture of the involved tissue is crucial for establishing the diagnosis of this infection. However, the rate of growth of M marinum is slow. Temperature requirements for incubation and delay in transporting specimens to the laboratory can lead to bacterial overgrowth, resulting in the inability to recover M marinum from the culture.¹³Mycobacterium marinum grows preferentially between 28°C and 32°C, and growth is limited at temperatures above 33°C.^13,15,16 As illustrated in the cases presented, recovery of the organism may not be accomplished from the first culture performed, and additional biopsy material for culture may be needed. Liquid media generally is more sensitive and produces more rapid results than solid media (eg, Löwenstein-Jensen, Middlebrook 7H10/7H11 agar). However, solid media carry the advantage of allowing observation of morphology and estimation of the number of organisms.^12,17

Rapid Detection
Advancements in molecular methods have allowed for more definitive and rapid identification of M marinum, substantially reducing the delay in diagnosis. Commercial molecular assays utilize in-solution hybridization or solid-format reverse-hybridization assays to allow mycobacterial detection as soon as growth appears.¹⁸ Use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry can substantially shorten the time to species identification.^19,20 Nonculture-based tests that have been developed for the rapid detection of M marinum infection include polymerase chain reaction-restriction fragment length polymorphism and polymerase chain reaction amplification of the 16S RNA gene.²¹ It should be noted, however, that M marinum and Mycobacterium ulcerans have a very homologous 16S ribosomal RNA gene sequence, differing by only 1 nucleotide; thus, distinguishing between M marinum and M ulcerans using this method may be challenging.^22,23

Management
Treatment depends on the extent of the disease. Generally, localized cutaneous disease can be treated with monotherapy with agents such as doxycycline, clarithromycin, or TMP-SMX. Extensive disease typically requires a combination of 2 antimycobacterial agents, typically clarithromycin-rifampin, clarithromycin-ethambutol, or rifampin-ethambutol.¹² Amikacin has been used in combination with other agents such as rifampin and clarithromycin in refractory cases.^22,24 The use of ciprofloxacin is not encouraged because some isolates are resistant; however, other fluoroquinolones, such as moxifloxacin, may be options for combination therapy. Isoniazid, pyrazinamide, and streptomycin are not effective to treat M marinum.

Susceptibility testing of M marinum usually is performed to guide antimicrobial therapy in cases of poor clinical response or intolerance to first-line antimicrobials such as macrolides.²⁵ The likelihood of M marinum developing resistance to the agents used for treatment appears to be low. Unfortunately, in vitro antimicrobial susceptibility tests do not correlate well with treatment efficiency.¹⁰

The duration of therapy is not standardized but usually is 5 to 6 months,^7,10,26 with therapy often continuing 1 to 2 months after lesions appear to have resolved.¹² However, in some cases (usually those who have more extensive disease), therapy has been extended to as long as 1 to 2 years.¹⁰ The ideal length of therapy in immunocompromised individuals has not been established²⁷; however, a treatment duration of 6 to 9 months was reported in one study.²⁸ Surgical debridement may be necessary in some patients who have involvement of deep structures of the hand or knee, those with persistent pain, or those who fail to respond to a prolonged period of medical therapy.²⁹ Successful use of less conventional therapeutic approaches, including cryotherapy, radiation therapy, electrodesiccation, photodynamic therapy, curettage, and local hyperthermic therapy has been reported.^30-32

Conclusion

Diagnosis and management of M marinum infection is difficult. Patients presenting with indolent nodular skin infections affecting the upper extremities should be asked about aquatic exposure. Tissue biopsy for histopathologic examination and culture is essential to establish an early diagnosis and promptly initiate appropriate therapy.

Acknowledgment
We would like to thank Carol A. Kauffman, MD (Ann Arbor, Michigan), for her thoughtful comments that greatly improved this manuscript.

An environmental pathogen, Mycobacterium marinum can cause cutaneous infection when traumatized skin is exposed to fresh, brackish, or salt water. Fishing, aquarium cleaning, and aquatic recreational activities are risk factors for infection.^1,2 Diagnosis often is delayed and is made several weeks or even months after initial symptoms appear.³ Due to the protracted clinical course, patients may not recall the initial exposure, contributing to the delay in diagnosis and initiation of appropriate treatment. It is not uncommon for patients with M marinum infection to be initially treated with antibiotics or antifungal drugs.

We present a review of 5 patients who were diagnosed with M marinum infection at our institution between January 2003 and March 2013.

Methods

This study was conducted at Henry Ford Hospital, a 900-bed tertiary care center in Detroit, Michigan. Patients who had cultures positive for M marinum between January 2003 and March 2013 were identified using the institution’s laboratory database. Medical records were reviewed, and relevant demographic, epidemiologic, and clinical data, including initial clinical presentation, alternative diagnoses, time between initial presentation and definitive diagnosis, and specific treatment, were recorded.

Results

We identified 5 patients who were diagnosed with culture-confirmed M marinum skin infections during the study period: 3 men and 2 women aged 43 to 72 years (Table 1). Two patients had diabetes mellitus and 1 had hepatitis C virus. None had classic immunosuppression. On repeated questioning after the diagnosis was established, all 5 patients reported that they kept a home aquarium, and all recalled mild trauma to the hand prior to the onset of symptoms; however, none of the patients initially linked the minor skin injury to the subsequent infection.

All 5 patients initially presented with erythema and swelling at the site of the injury, which evolved into inflammatory nodules that progressed proximally up to the arm despite empiric treatment with antibiotics active against streptococci and staphylococci (Figures 1 and 2). Three patients also received empiric antifungal therapy due to suspicion of sporotrichosis.

Skin biopsies were performed on 4 patients, and incision and drainage of purulent material was performed on the fifth patient. Histopathologic examination revealed granulomatous inflammation in 3 patients. Stains for acid-fast bacilli were positive in all 5 patients. Definitive diagnosis of the organism was confirmed by growth of M marinum within 11 to 40 days from the tissue in 4 patients and purulent material in the fifth patient. Susceptibility testing was performed on only 1 of the 5 isolates and showed that the organism was susceptible to amikacin, clarithromycin, doxycycline, ethambutol, rifampin, and trimethoprim-sulfamethoxazole (TMP-SMX).

The mean time from initial presentation to initiation of appropriate therapy for M marinum infection was 91 days (range, 21–245 days). Several different treatment regimens were used. All patients received either doxycycline or minocycline with or without a macrolide. Two also received other agents (TMP-SMX or ethambutol). Treatment duration varied from 2 to 6 months in 4 patients, and all 4 had complete resolution of the lesions; 1 patient was lost to follow-up.

Comment

Diagnosing the Infection
Diagnosis of M marinum infection remains problematic. In the 5 patients included in this study, the time between initial onset of symptoms and diagnosis of M marinum infection was delayed, as has been noted in other reports.^4-7 Delays as long as 2 years before the diagnosis is made have been described.⁷ The clinical presentation of cutaneous infection with M marinum varies, which may delay diagnosis. Nodular lymphangitis is classic, but papules, pustules, ulcers, inflammatory plaques, and single nodules also can occur.^1,2 Lymphadenopathy may or may not be present.^4,8,9 The differential diagnosis is broad and includes infection by other nontuberculous mycobacteria such as Mycobacterium chelonae; Mycobacterium fortuitum; Nocardia species, especially Nocardia brasiliensis; Francisella tularensis; Sporothrix schenckii; and Leishmania species. It is not surprising that 4 patients in our study were initially treated for a gram-positive bacterial infection and 3 were treated for a fungal infection before the diagnosis of M marinum was made. Distinctive features that may help to differentiate these infections are summarized in Table 2.

We found that the main cause of delayed diagnosis was the failure of physicians to obtain a thorough history regarding patients’ recreational activities and animal exposure. Patients often do not associate a remote aquatic exposure with their symptoms and will not volunteer this information unless directly asked.^2,10 It was only after repeated questioning in all of these patients that they recounted prior trauma to the involved hand related to the aquarium.

Biopsy and Culture
Histopathologic examination of material from a biopsied lesion can give an early clue that a mycobacterial infection might be involved. Biopsy can reveal either noncaseating or necrotizing granulomas that have larger numbers of neutrophils in addition to lymphocytes and macrophages. Giant cells often are noted.^5,9,11 Organisms can be seen with the use of a tissue acid-fast stain, but species cannot be differentiated by acid-fast staining.¹² However, the sensitivity of acid-fast stains on biopsy material is low.^3,13,14

Culture of the involved tissue is crucial for establishing the diagnosis of this infection. However, the rate of growth of M marinum is slow. Temperature requirements for incubation and delay in transporting specimens to the laboratory can lead to bacterial overgrowth, resulting in the inability to recover M marinum from the culture.¹³Mycobacterium marinum grows preferentially between 28°C and 32°C, and growth is limited at temperatures above 33°C.^13,15,16 As illustrated in the cases presented, recovery of the organism may not be accomplished from the first culture performed, and additional biopsy material for culture may be needed. Liquid media generally is more sensitive and produces more rapid results than solid media (eg, Löwenstein-Jensen, Middlebrook 7H10/7H11 agar). However, solid media carry the advantage of allowing observation of morphology and estimation of the number of organisms.^12,17

Rapid Detection
Advancements in molecular methods have allowed for more definitive and rapid identification of M marinum, substantially reducing the delay in diagnosis. Commercial molecular assays utilize in-solution hybridization or solid-format reverse-hybridization assays to allow mycobacterial detection as soon as growth appears.¹⁸ Use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry can substantially shorten the time to species identification.^19,20 Nonculture-based tests that have been developed for the rapid detection of M marinum infection include polymerase chain reaction-restriction fragment length polymorphism and polymerase chain reaction amplification of the 16S RNA gene.²¹ It should be noted, however, that M marinum and Mycobacterium ulcerans have a very homologous 16S ribosomal RNA gene sequence, differing by only 1 nucleotide; thus, distinguishing between M marinum and M ulcerans using this method may be challenging.^22,23

Management
Treatment depends on the extent of the disease. Generally, localized cutaneous disease can be treated with monotherapy with agents such as doxycycline, clarithromycin, or TMP-SMX. Extensive disease typically requires a combination of 2 antimycobacterial agents, typically clarithromycin-rifampin, clarithromycin-ethambutol, or rifampin-ethambutol.¹² Amikacin has been used in combination with other agents such as rifampin and clarithromycin in refractory cases.^22,24 The use of ciprofloxacin is not encouraged because some isolates are resistant; however, other fluoroquinolones, such as moxifloxacin, may be options for combination therapy. Isoniazid, pyrazinamide, and streptomycin are not effective to treat M marinum.

Susceptibility testing of M marinum usually is performed to guide antimicrobial therapy in cases of poor clinical response or intolerance to first-line antimicrobials such as macrolides.²⁵ The likelihood of M marinum developing resistance to the agents used for treatment appears to be low. Unfortunately, in vitro antimicrobial susceptibility tests do not correlate well with treatment efficiency.¹⁰

The duration of therapy is not standardized but usually is 5 to 6 months,^7,10,26 with therapy often continuing 1 to 2 months after lesions appear to have resolved.¹² However, in some cases (usually those who have more extensive disease), therapy has been extended to as long as 1 to 2 years.¹⁰ The ideal length of therapy in immunocompromised individuals has not been established²⁷; however, a treatment duration of 6 to 9 months was reported in one study.²⁸ Surgical debridement may be necessary in some patients who have involvement of deep structures of the hand or knee, those with persistent pain, or those who fail to respond to a prolonged period of medical therapy.²⁹ Successful use of less conventional therapeutic approaches, including cryotherapy, radiation therapy, electrodesiccation, photodynamic therapy, curettage, and local hyperthermic therapy has been reported.^30-32

Conclusion

Diagnosis and management of M marinum infection is difficult. Patients presenting with indolent nodular skin infections affecting the upper extremities should be asked about aquatic exposure. Tissue biopsy for histopathologic examination and culture is essential to establish an early diagnosis and promptly initiate appropriate therapy.

Acknowledgment
We would like to thank Carol A. Kauffman, MD (Ann Arbor, Michigan), for her thoughtful comments that greatly improved this manuscript.

An environmental pathogen, Mycobacterium marinum can cause cutaneous infection when traumatized skin is exposed to fresh, brackish, or salt water. Fishing, aquarium cleaning, and aquatic recreational activities are risk factors for infection.^1,2 Diagnosis often is delayed and is made several weeks or even months after initial symptoms appear.³ Due to the protracted clinical course, patients may not recall the initial exposure, contributing to the delay in diagnosis and initiation of appropriate treatment. It is not uncommon for patients with M marinum infection to be initially treated with antibiotics or antifungal drugs.

We present a review of 5 patients who were diagnosed with M marinum infection at our institution between January 2003 and March 2013.

Methods

This study was conducted at Henry Ford Hospital, a 900-bed tertiary care center in Detroit, Michigan. Patients who had cultures positive for M marinum between January 2003 and March 2013 were identified using the institution’s laboratory database. Medical records were reviewed, and relevant demographic, epidemiologic, and clinical data, including initial clinical presentation, alternative diagnoses, time between initial presentation and definitive diagnosis, and specific treatment, were recorded.

Results

We identified 5 patients who were diagnosed with culture-confirmed M marinum skin infections during the study period: 3 men and 2 women aged 43 to 72 years (Table 1). Two patients had diabetes mellitus and 1 had hepatitis C virus. None had classic immunosuppression. On repeated questioning after the diagnosis was established, all 5 patients reported that they kept a home aquarium, and all recalled mild trauma to the hand prior to the onset of symptoms; however, none of the patients initially linked the minor skin injury to the subsequent infection.

All 5 patients initially presented with erythema and swelling at the site of the injury, which evolved into inflammatory nodules that progressed proximally up to the arm despite empiric treatment with antibiotics active against streptococci and staphylococci (Figures 1 and 2). Three patients also received empiric antifungal therapy due to suspicion of sporotrichosis.

Skin biopsies were performed on 4 patients, and incision and drainage of purulent material was performed on the fifth patient. Histopathologic examination revealed granulomatous inflammation in 3 patients. Stains for acid-fast bacilli were positive in all 5 patients. Definitive diagnosis of the organism was confirmed by growth of M marinum within 11 to 40 days from the tissue in 4 patients and purulent material in the fifth patient. Susceptibility testing was performed on only 1 of the 5 isolates and showed that the organism was susceptible to amikacin, clarithromycin, doxycycline, ethambutol, rifampin, and trimethoprim-sulfamethoxazole (TMP-SMX).

The mean time from initial presentation to initiation of appropriate therapy for M marinum infection was 91 days (range, 21–245 days). Several different treatment regimens were used. All patients received either doxycycline or minocycline with or without a macrolide. Two also received other agents (TMP-SMX or ethambutol). Treatment duration varied from 2 to 6 months in 4 patients, and all 4 had complete resolution of the lesions; 1 patient was lost to follow-up.

Comment

Diagnosing the Infection
Diagnosis of M marinum infection remains problematic. In the 5 patients included in this study, the time between initial onset of symptoms and diagnosis of M marinum infection was delayed, as has been noted in other reports.^4-7 Delays as long as 2 years before the diagnosis is made have been described.⁷ The clinical presentation of cutaneous infection with M marinum varies, which may delay diagnosis. Nodular lymphangitis is classic, but papules, pustules, ulcers, inflammatory plaques, and single nodules also can occur.^1,2 Lymphadenopathy may or may not be present.^4,8,9 The differential diagnosis is broad and includes infection by other nontuberculous mycobacteria such as Mycobacterium chelonae; Mycobacterium fortuitum; Nocardia species, especially Nocardia brasiliensis; Francisella tularensis; Sporothrix schenckii; and Leishmania species. It is not surprising that 4 patients in our study were initially treated for a gram-positive bacterial infection and 3 were treated for a fungal infection before the diagnosis of M marinum was made. Distinctive features that may help to differentiate these infections are summarized in Table 2.

We found that the main cause of delayed diagnosis was the failure of physicians to obtain a thorough history regarding patients’ recreational activities and animal exposure. Patients often do not associate a remote aquatic exposure with their symptoms and will not volunteer this information unless directly asked.^2,10 It was only after repeated questioning in all of these patients that they recounted prior trauma to the involved hand related to the aquarium.

Biopsy and Culture
Histopathologic examination of material from a biopsied lesion can give an early clue that a mycobacterial infection might be involved. Biopsy can reveal either noncaseating or necrotizing granulomas that have larger numbers of neutrophils in addition to lymphocytes and macrophages. Giant cells often are noted.^5,9,11 Organisms can be seen with the use of a tissue acid-fast stain, but species cannot be differentiated by acid-fast staining.¹² However, the sensitivity of acid-fast stains on biopsy material is low.^3,13,14

Culture of the involved tissue is crucial for establishing the diagnosis of this infection. However, the rate of growth of M marinum is slow. Temperature requirements for incubation and delay in transporting specimens to the laboratory can lead to bacterial overgrowth, resulting in the inability to recover M marinum from the culture.¹³Mycobacterium marinum grows preferentially between 28°C and 32°C, and growth is limited at temperatures above 33°C.^13,15,16 As illustrated in the cases presented, recovery of the organism may not be accomplished from the first culture performed, and additional biopsy material for culture may be needed. Liquid media generally is more sensitive and produces more rapid results than solid media (eg, Löwenstein-Jensen, Middlebrook 7H10/7H11 agar). However, solid media carry the advantage of allowing observation of morphology and estimation of the number of organisms.^12,17

Rapid Detection
Advancements in molecular methods have allowed for more definitive and rapid identification of M marinum, substantially reducing the delay in diagnosis. Commercial molecular assays utilize in-solution hybridization or solid-format reverse-hybridization assays to allow mycobacterial detection as soon as growth appears.¹⁸ Use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry can substantially shorten the time to species identification.^19,20 Nonculture-based tests that have been developed for the rapid detection of M marinum infection include polymerase chain reaction-restriction fragment length polymorphism and polymerase chain reaction amplification of the 16S RNA gene.²¹ It should be noted, however, that M marinum and Mycobacterium ulcerans have a very homologous 16S ribosomal RNA gene sequence, differing by only 1 nucleotide; thus, distinguishing between M marinum and M ulcerans using this method may be challenging.^22,23

Management
Treatment depends on the extent of the disease. Generally, localized cutaneous disease can be treated with monotherapy with agents such as doxycycline, clarithromycin, or TMP-SMX. Extensive disease typically requires a combination of 2 antimycobacterial agents, typically clarithromycin-rifampin, clarithromycin-ethambutol, or rifampin-ethambutol.¹² Amikacin has been used in combination with other agents such as rifampin and clarithromycin in refractory cases.^22,24 The use of ciprofloxacin is not encouraged because some isolates are resistant; however, other fluoroquinolones, such as moxifloxacin, may be options for combination therapy. Isoniazid, pyrazinamide, and streptomycin are not effective to treat M marinum.

Susceptibility testing of M marinum usually is performed to guide antimicrobial therapy in cases of poor clinical response or intolerance to first-line antimicrobials such as macrolides.²⁵ The likelihood of M marinum developing resistance to the agents used for treatment appears to be low. Unfortunately, in vitro antimicrobial susceptibility tests do not correlate well with treatment efficiency.¹⁰

The duration of therapy is not standardized but usually is 5 to 6 months,^7,10,26 with therapy often continuing 1 to 2 months after lesions appear to have resolved.¹² However, in some cases (usually those who have more extensive disease), therapy has been extended to as long as 1 to 2 years.¹⁰ The ideal length of therapy in immunocompromised individuals has not been established²⁷; however, a treatment duration of 6 to 9 months was reported in one study.²⁸ Surgical debridement may be necessary in some patients who have involvement of deep structures of the hand or knee, those with persistent pain, or those who fail to respond to a prolonged period of medical therapy.²⁹ Successful use of less conventional therapeutic approaches, including cryotherapy, radiation therapy, electrodesiccation, photodynamic therapy, curettage, and local hyperthermic therapy has been reported.^30-32

Conclusion

Diagnosis and management of M marinum infection is difficult. Patients presenting with indolent nodular skin infections affecting the upper extremities should be asked about aquatic exposure. Tissue biopsy for histopathologic examination and culture is essential to establish an early diagnosis and promptly initiate appropriate therapy.

Acknowledgment
We would like to thank Carol A. Kauffman, MD (Ann Arbor, Michigan), for her thoughtful comments that greatly improved this manuscript.

Take-Home Points

• Patella alta has a reduced articular area of PF contact.
• Presence of patella alta depends on the measurement method.
• Patella alta is defined as ISI >1.2 and CDI >1.2 to >1.3.
• On sagittal MRI, PTI is used most often with cutoff values of <0.125 to 0.28.
• Tibial tubercle distalization is most often used to treat patella alta. The desired postoperative patellar height is a CDI of 1.0.

Patella alta is a patella that rides abnormally high in relation to the femur, the femoral trochlea, or the tibia,¹ with decreased bony stability requiring increased knee flexion angles to engage the trochlea.^2,3 An abnormally high patella may therefore insufficiently engage the proximal trochlea groove both in extension and in the early phase of knee flexion—making it one of the potential risk factors for patellar instability.^4-10 Accordingly, patella alta is present in 30% of patients with recurrent patellar dislocation.¹¹ It also occurs in other disorders, such as knee extensor apparatus disorders, in patients with patellofemoral (PF) pain, chondromalacia, Sinding-Larsen-Johansson disease, Osgood-Schlatter disease, patellar tendinopathy, and osteoarthritis.^1,7,8,12-18 As such, patella alta represents an important predisposing factor for patellar malalignment and PF-related complaints. On the other hand, patella alta may also be a normal variant of a person’s knee anatomy and may be well tolerated when not combined with other instability factors.⁴

Despite the importance of patella alta, there is no consensus on a precise definition, the most reliable measurement method, or the factors thought to be important in clinical decisions regarding treatment. To address this issue, we systematically reviewed the patella alta literature for definitions, the most common measurement methods and their patella alta cutoff values, and cutoff values for surgical correction and proposed surgical techniques.

Methods

In February 2017, using the term patella alta, we performed a systematic literature search on PubMed. Inclusion criteria were original study or review articles, publication in peer-reviewed English-language journals between 2000 and 2017, and narrative description or measurement of human patellar height on plain radiographs or magnetic resonance imaging (MRI). Excluded were abstracts and articles in languages other than English; animal and computational/biomechanical studies; case reports; and knee arthroplasties, knee extensor ruptures, and hereditary and congenital diseases. All evidence levels were included.

We assessed measurement methods, reported cutoff values for patella alta, cutoff values for performing surgical correction, proposed surgical techniques, and postoperative target values. Original study articles and review articles were analyzed separately.

Results

Of 211 articles identified, 92 met the inclusion criteria for original study, and 28 for review. All their abstracts were reviewed, and 91 were excluded: 17 for language other than English, 11 for animal study, 12 for biomechanical/computational study, 20 for case report, 8 for arthroplasty, 13 for hereditary or congenital disease, 1 for extensor apparatus rupture, 3 for editorial letter, and 6 for other reasons. Full text copies of all included articles were obtained and reviewed.

Original Study Articles

Definition. Of the 92 original study articles, 17 (18.5%) defined patella alta by description alone, and 75 (81.5%) used imaging-based measurements. Patella alta was described as a patella that rides abnormally high in relation to the trochlear groove, with a reduced articular area of PF contact^1,15,19-21 or decreased patella–trochlea cartilage overlap.²² With this reduced contact area, there is increased PF stress.²¹

With radiographic measurements, patella alta is defined as a Caton-Deschamps index (CDI) of >1.2 to >1.3, an Insall-Salvati index (ISI) of >1.2, a Blackburne-Peel index (PBI) of >1.0,^{4,15,18,23-25} and a patellotrochlear index (PTI) of <0.125 to 0.28.^6,26

On lateral radiographs, ISI was the most common measurement (33 studies), with patella alta cutoff values ranging from >1.2 to >1.5. The second most common measurement was CDI (24 studies), with cutoff values of >1.2 to >1.3. Other indices, such as the modified ISI (6 studies), the BPI (1 study), and the Koshino index (2 studies), had their cutoff values used more consistently (>1.6 to >2.4, >1.0, and >1.2, respectively) but these indices were rarely reported in the literature (Table 1).^27,28,29 

Thirty-six studies defined patella alta with MRI using either the aforementioned radiographic ratios (23 studies, 3 indices, Table 2) or PF indices (13 studies, 4 methods, Table 3).³⁰ 

On sagittal MRI, PTI was used most often; cutoff values were <0.125 to 0.28.

Thirteen studies defined patella alta with PTL: 5 using lateral conventional radiographs and 8 using sagittal MRI. For each type of imaging, the cutoff value was >52 mm to >56 mm. PTL was measured either independently or together with ISI on sagittal MRI (Table 4).

22

Review Articles

Twenty-eight review articles met the inclusion criteria.^35-40 Patella alta was described mostly with ISI (75%) or CDI (64%). In up to 57% of these articles, a patella alta reference value was missing. Only 1 article mentioned different cutoff values for conventional radiographs and MRI. BPI was mentioned in 50% of studies, but only 2 indicated a cutoff value for patella alta. Eleven percent used PTI on sagittal MRI and took patella–trochlea cartilage overlap into account.

Eight review articles mentioned cutoff values for surgical correction. Only 1 of 4 articles mentioned a cutoff value for correcting patella alta in PF instability, and only 2 articles suggested an ideal postoperative patellar height (Table 6).

No review article relied on PTL to describe patella alta or to advise surgical treatment.

Discussion 

Our review revealed many variations in patella alta definitions and descriptions, measurement methods, cutoff values, and treatment options. Interpretation of patellar height and, particularly, patella alta is very heterogeneous. Accordingly, comparing surgical indications, surgical treatment options, and outcomes across studies can be difficult.

Measurement Methods

Radiographs. Conventional radiographs were used to describe patella alta in two-thirds of the original study articles. The most common measurement methods marked the position of the patella relative to either the femur (direct assessment) or the tibia (indirect assessment).^14,25 All established measurement methods use lateral radiographs, which do not show articular cartilage.^11,14 Therefore, lateral radiograph ratios of different and variable bony landmarks do not measure actual PF articular congruence. The widely variable morphologies of patella (distal patellar nose, different articulating surface), femoral trochlea (facet in height and length), proximal tibia (inherited or acquired deformities on tibial tubercle), and slope are all confounding factors that may affect measurement (Figure 1). In addition, specific variations in PF joint morphology (eg, small patellar articular surface, short trochlea) are not well represented by these ratios.¹¹

All these methods have advantages, limitations, and different values of interobserver and intraobserver variability, reliability, and reproducibility (Table 7).^29,41

Determination of both patellar height and patella alta depends on the measurement method used and is significantly affected by anatomical variants, such as extra-articular patella and femorotibial landmarks. 

The ISI method is most commonly used because it does not depend on degree of knee flexion, is thought to measure the relative length of the patellar tendon the best,⁵ and has established MRI criteria.⁶ However, ISI has limitations: Its distal bony landmark is the tibial tuberosity, which can be difficult to assess¹⁴; the shape of the patella (mainly its inferior point) varies⁴²; and the measurement does not change after distalization of the tibial tubercle.⁵

CDI is the most accurate diagnostic method because it relies on readily identifiable and reproducible anatomical landmarks; does not depend on radiograph quality, knee size, radiologic enlargement, or position of the tibial tubercle or patellar modification; and is unaffected by degree of knee flexion between 10° and 80°.^38,43 CDI is the method that is most useful in describing patellar height after distalization of the tibial tubercle because it assesses the height of the patella relative to the tibial plateau.⁵ CDI is limited with respect to clear identification of the patellar and tibial articular margin.³⁷

BPI has the lowest interobserver variability and discriminates best among patella alta, norma, and infera.⁴¹ Like CDI, BPI assesses patellar height relative to the tibial plateau, and thus is useful in describing patellar height after distalization of the tibial tubercle.⁵ BPI is limited in that it uses a line drawn along the tibial plateau, where variations in inclination and tibial slope produce inaccuracies,¹⁴ and depends highly on projection angles. Clinically, BPI is rarely used.

As the literature shows, the radiologic methods of determining patellar height are variable and unreliable and depend on the ratio used.^26,41 These methods do not reveal precise information about the PF articular congruence, the key finding for necessary treatment.

Radiographic Indices on MRI. Some studies measured radiographic indices on sagittal MRI. Radiologic and MRI measurements are described as not significantly different or slightly different, and 0.09 to 0.13 needs to be added with ISI and BP ratios on radiographs, MRI, and computed tomography (CT).^17,44-47 ISI is commonly used, and its clinical application is easy. Although classically measured on plain radiographs, ISI is reliably measured on MRI as well.^17,30 The traditional 1.2 threshold for defining patella alta was used by Charles and colleagues.⁴⁴ CDI is equally well measured on radiographs and MRI.⁴⁷

According to the literature, 3 different measurement methods have been used to describe degree of patella–trochlea cartilage overlap: PTI, sagittal patellofemoral engagement (SPE), and patellar articular overlap (PAO).^1,11,26

PTI uses the true articular cartilage patella–trochlea relationship for measurement of patellar height on sagittal MRI in extension (Figure 3). If the patellar tendon is fully out to length (no laxity), PTI reliably and precisely determines the exact articular correlation of PF joint and patellar height.⁶

SPE is similar to percentage of articular coverage.^1,11 Patellar overlap of the trochlea is measured on 2 different sagittal MRI images: 1 with the greatest length of patellar cartilage and 1 with the greatest length of femoral trochlear cartilage. This measurement did not correlate with CDI.¹ SPE was not evaluated in control studies, and normal and pathologic values are unavailable.

PAO is measured with patients positioned at rest and in standard knee coils.¹ MRI was not obtained in full extension or with quadriceps activation, and knee flexion angle values are unavailable. Total patellar articular length was measured on the sagittal MRI that showed the greatest patellar length and articular cartilage thickness. The same image was used to measure articular overlap, or the length of patellar cartilage overlying the trochlear cartilage, as measured parallel to the subchondral surface of the patella. PAO correlates well with conventional patellar height measurements in the sagittal plane and shows promise as a simpler alternative to the conventional indices.¹ Normal and pathologic values are unavailable.

So far, PTI is the only method that was controlled in several studies, assessed for its reliability, and compared with other patellar height measurements.^6,14

Patellar Tendon Length. PTL can be measured on lateral radiographs or sagittal MRI. Radiologic and MRI measurements are described as not significantly different⁴⁷ or slightly different, and 0.09 to 0.13 needs to be added with the ISI ratio on radiographs, MRI, and CT.⁴⁶ PTL is reliably evaluated with ISI.^41,50 There is a weak correlation of patient height and PTL: Taller people have normally longer tendons.^51-53

PTL measurements revealed that the posterior surface of the patellar tendon was significantly shorter than the anterior surface. Compared with their corresponding posterior fascicles, anterior fascicles are longer; their attachment is more proximal to the patella and more distal to the tibia. In addition, posterior PTL is significantly shorter with the posterior patellar attachment (adheres to posterior aspect of the inferior patellar pole) than with the anterior attachment (adheres to anterior aspect of the inferior patellar pole).⁵⁶ Moreover, the lateral and medial fascicles are longer than the central fascicles attaching at the most inferior patellar pole. This issue must be considered in image cut selection (Figures 6A, 6B). Furthermore, type of inferior pole of patella (pointed, intermediate, blunt) is important in measurement.⁵⁶ Overall, mean (SD) PTL was 54.9 (1.2) mm on the anterior surface and 35.0 (0.6) mm on the posterior surface.

It is important to precisely describe the measurement method and location (sagittal cut) and to consider the shape of the inferior patellar pole and the site of the patellar tendon attachment.⁵⁶

Treatments. For patella alta, the surgical treatment goals are to increase the PF contact area and improve PF articular congruence, and thereby increase PF stability.^31-33 Four different procedures were used to treat patella alta (Table 5), but only 11 of the 92 original study articles and 8 of the 28 review articles included in our review mentioned a specific patellar height that required surgical correction (Tables 5, 6). Recommendations were based on CDI (>1.2 to >1.4) and less often on ISI (>1.2 to >1.4) or PTL (>56 mm).

Tibial tubercle distalization is effective in normalizing patellar height to correct the patellar index in patella alta (Figures 7A, 7B).^{13,18,38,55,57} Tibial tubercle distalization and patellar tendon tenodesis attached to the original insertion normalize PTL and stabilize the PF joint in patients with patella alta.^5,47 In a comparison of these surgical procedures, cartilage stress was lower with distalization than with distalization and tenodesis.¹³

Soft-tissue methods are recommended in children, as bone procedures injure the proximal tibial physis and may cause it to close prematurely.⁵⁸ The patella can be distally advanced by completely mobilizing the patellar tendon and fixating with sutures through the cartilaginous tibial tubercle. This technique is a satisfactory treatment for skeletally immature patients who present with habitual patellar dislocation associated with patella alta.^58,59

CDI and BPI assess patellar height relative to the tibial plateau, and therefore are the most useful measurement methods for patellar height after distalization of the tibial tubercle.⁵ ISI does not change after distalization of the tibial tubercle and cannot be recommended.^5,18 As PF indices (eg, PTI) can trace preoperative and postoperative values, these measurements are valuable.

Controversies

Our review found no consensus on measurement method or cutoff value. No measurement method showed clear clinical or methodologic superiority. Most published patellar height and patella alta data are based on conventional radiographs using a tibial reference point, even though a femoral or even trochlear reference point seems more reproducible, particularly in PF pathologies. Several cutoff values have been reported for each patella alta measurement method. Regarding pathologic thresholds, which might require surgical correction, very little information has been published, and scientific evidence is lacking. Numerous important aspects remain unanswered after this review, and clarification is mandatory.

Five Key Facts

1. In patella alta assessment, different morphologic, biomechanical, and functional aspects must be considered. The most relevant aspect is decreased engagement of the patella and trochlea,^4-9,11,26 which results in decreased bony stability in knee extension.^1-3 Therefore, patella alta is one of the potential risk factors for patellar instability with a high percentage of recurrent patellar dislocation.^4-9 In early knee flexion, the patella translates more distally with better engagement of the patella in the trochlea and better stability. Therefore, measurement in extension, with the patellar tendon out to length, seems to offer a more reliable assessment of the patella–femur relationship.

2. Insufficient engagement of the patella in the trochlea is the most important aspect of patella alta.¹¹ Therefore, direct measurement of this engagement seems logical.

3. As radiographs do not show articular cartilage, they should not be used to assess the articular patella–femur relationship.^11,14,26 Patella–trochlea cartilage overlap is the most relevant factor for patella alta and should be measured on MRI.^6,14,26,32

4. PTL is an important factor for patellar height and particularly patella alta. The range of normal PTL values is wide: 35 mm to 61 mm. The described cutoff values for patella alta (>52 mm to >56 mm) fall within this normal range. The cause may be the different measurement methods used.^33,47,59-61 Therefore, for precise diagnostics, a standardized measurement method that includes the selected cut imaging is mandatory.

Conclusion 

Our review revealed many variations in patella alta definitions and descriptions, measurement methods, cutoff values, and treatment options. Presence of patella alta depends on measurement method used. Methods cannot be used interchangeably, and they all have their advantages and limitations. Unfortunately, there is no generally accepted consensus on measurement method, patella alta cutoff value, or treatment with ideal correction. Treatment planning and outcomes assessment require clarification of these many issues.

Take-Home Points

• Patella alta has a reduced articular area of PF contact.
• Presence of patella alta depends on the measurement method.
• Patella alta is defined as ISI >1.2 and CDI >1.2 to >1.3.
• On sagittal MRI, PTI is used most often with cutoff values of <0.125 to 0.28.
• Tibial tubercle distalization is most often used to treat patella alta. The desired postoperative patellar height is a CDI of 1.0.

Patella alta is a patella that rides abnormally high in relation to the femur, the femoral trochlea, or the tibia,¹ with decreased bony stability requiring increased knee flexion angles to engage the trochlea.^2,3 An abnormally high patella may therefore insufficiently engage the proximal trochlea groove both in extension and in the early phase of knee flexion—making it one of the potential risk factors for patellar instability.^4-10 Accordingly, patella alta is present in 30% of patients with recurrent patellar dislocation.¹¹ It also occurs in other disorders, such as knee extensor apparatus disorders, in patients with patellofemoral (PF) pain, chondromalacia, Sinding-Larsen-Johansson disease, Osgood-Schlatter disease, patellar tendinopathy, and osteoarthritis.^1,7,8,12-18 As such, patella alta represents an important predisposing factor for patellar malalignment and PF-related complaints. On the other hand, patella alta may also be a normal variant of a person’s knee anatomy and may be well tolerated when not combined with other instability factors.⁴

Despite the importance of patella alta, there is no consensus on a precise definition, the most reliable measurement method, or the factors thought to be important in clinical decisions regarding treatment. To address this issue, we systematically reviewed the patella alta literature for definitions, the most common measurement methods and their patella alta cutoff values, and cutoff values for surgical correction and proposed surgical techniques.

Methods

In February 2017, using the term patella alta, we performed a systematic literature search on PubMed. Inclusion criteria were original study or review articles, publication in peer-reviewed English-language journals between 2000 and 2017, and narrative description or measurement of human patellar height on plain radiographs or magnetic resonance imaging (MRI). Excluded were abstracts and articles in languages other than English; animal and computational/biomechanical studies; case reports; and knee arthroplasties, knee extensor ruptures, and hereditary and congenital diseases. All evidence levels were included.

We assessed measurement methods, reported cutoff values for patella alta, cutoff values for performing surgical correction, proposed surgical techniques, and postoperative target values. Original study articles and review articles were analyzed separately.

Results

Of 211 articles identified, 92 met the inclusion criteria for original study, and 28 for review. All their abstracts were reviewed, and 91 were excluded: 17 for language other than English, 11 for animal study, 12 for biomechanical/computational study, 20 for case report, 8 for arthroplasty, 13 for hereditary or congenital disease, 1 for extensor apparatus rupture, 3 for editorial letter, and 6 for other reasons. Full text copies of all included articles were obtained and reviewed.

Original Study Articles

Definition. Of the 92 original study articles, 17 (18.5%) defined patella alta by description alone, and 75 (81.5%) used imaging-based measurements. Patella alta was described as a patella that rides abnormally high in relation to the trochlear groove, with a reduced articular area of PF contact^1,15,19-21 or decreased patella–trochlea cartilage overlap.²² With this reduced contact area, there is increased PF stress.²¹

With radiographic measurements, patella alta is defined as a Caton-Deschamps index (CDI) of >1.2 to >1.3, an Insall-Salvati index (ISI) of >1.2, a Blackburne-Peel index (PBI) of >1.0,^{4,15,18,23-25} and a patellotrochlear index (PTI) of <0.125 to 0.28.^6,26

On lateral radiographs, ISI was the most common measurement (33 studies), with patella alta cutoff values ranging from >1.2 to >1.5. The second most common measurement was CDI (24 studies), with cutoff values of >1.2 to >1.3. Other indices, such as the modified ISI (6 studies), the BPI (1 study), and the Koshino index (2 studies), had their cutoff values used more consistently (>1.6 to >2.4, >1.0, and >1.2, respectively) but these indices were rarely reported in the literature (Table 1).^27,28,29 

Thirty-six studies defined patella alta with MRI using either the aforementioned radiographic ratios (23 studies, 3 indices, Table 2) or PF indices (13 studies, 4 methods, Table 3).³⁰ 

On sagittal MRI, PTI was used most often; cutoff values were <0.125 to 0.28.

Thirteen studies defined patella alta with PTL: 5 using lateral conventional radiographs and 8 using sagittal MRI. For each type of imaging, the cutoff value was >52 mm to >56 mm. PTL was measured either independently or together with ISI on sagittal MRI (Table 4).

22

Review Articles

Twenty-eight review articles met the inclusion criteria.^35-40 Patella alta was described mostly with ISI (75%) or CDI (64%). In up to 57% of these articles, a patella alta reference value was missing. Only 1 article mentioned different cutoff values for conventional radiographs and MRI. BPI was mentioned in 50% of studies, but only 2 indicated a cutoff value for patella alta. Eleven percent used PTI on sagittal MRI and took patella–trochlea cartilage overlap into account.

Eight review articles mentioned cutoff values for surgical correction. Only 1 of 4 articles mentioned a cutoff value for correcting patella alta in PF instability, and only 2 articles suggested an ideal postoperative patellar height (Table 6).

No review article relied on PTL to describe patella alta or to advise surgical treatment.

Discussion 

Our review revealed many variations in patella alta definitions and descriptions, measurement methods, cutoff values, and treatment options. Interpretation of patellar height and, particularly, patella alta is very heterogeneous. Accordingly, comparing surgical indications, surgical treatment options, and outcomes across studies can be difficult.

Measurement Methods

Radiographs. Conventional radiographs were used to describe patella alta in two-thirds of the original study articles. The most common measurement methods marked the position of the patella relative to either the femur (direct assessment) or the tibia (indirect assessment).^14,25 All established measurement methods use lateral radiographs, which do not show articular cartilage.^11,14 Therefore, lateral radiograph ratios of different and variable bony landmarks do not measure actual PF articular congruence. The widely variable morphologies of patella (distal patellar nose, different articulating surface), femoral trochlea (facet in height and length), proximal tibia (inherited or acquired deformities on tibial tubercle), and slope are all confounding factors that may affect measurement (Figure 1). In addition, specific variations in PF joint morphology (eg, small patellar articular surface, short trochlea) are not well represented by these ratios.¹¹

All these methods have advantages, limitations, and different values of interobserver and intraobserver variability, reliability, and reproducibility (Table 7).^29,41

Determination of both patellar height and patella alta depends on the measurement method used and is significantly affected by anatomical variants, such as extra-articular patella and femorotibial landmarks. 

The ISI method is most commonly used because it does not depend on degree of knee flexion, is thought to measure the relative length of the patellar tendon the best,⁵ and has established MRI criteria.⁶ However, ISI has limitations: Its distal bony landmark is the tibial tuberosity, which can be difficult to assess¹⁴; the shape of the patella (mainly its inferior point) varies⁴²; and the measurement does not change after distalization of the tibial tubercle.⁵

CDI is the most accurate diagnostic method because it relies on readily identifiable and reproducible anatomical landmarks; does not depend on radiograph quality, knee size, radiologic enlargement, or position of the tibial tubercle or patellar modification; and is unaffected by degree of knee flexion between 10° and 80°.^38,43 CDI is the method that is most useful in describing patellar height after distalization of the tibial tubercle because it assesses the height of the patella relative to the tibial plateau.⁵ CDI is limited with respect to clear identification of the patellar and tibial articular margin.³⁷

BPI has the lowest interobserver variability and discriminates best among patella alta, norma, and infera.⁴¹ Like CDI, BPI assesses patellar height relative to the tibial plateau, and thus is useful in describing patellar height after distalization of the tibial tubercle.⁵ BPI is limited in that it uses a line drawn along the tibial plateau, where variations in inclination and tibial slope produce inaccuracies,¹⁴ and depends highly on projection angles. Clinically, BPI is rarely used.

As the literature shows, the radiologic methods of determining patellar height are variable and unreliable and depend on the ratio used.^26,41 These methods do not reveal precise information about the PF articular congruence, the key finding for necessary treatment.

Radiographic Indices on MRI. Some studies measured radiographic indices on sagittal MRI. Radiologic and MRI measurements are described as not significantly different or slightly different, and 0.09 to 0.13 needs to be added with ISI and BP ratios on radiographs, MRI, and computed tomography (CT).^17,44-47 ISI is commonly used, and its clinical application is easy. Although classically measured on plain radiographs, ISI is reliably measured on MRI as well.^17,30 The traditional 1.2 threshold for defining patella alta was used by Charles and colleagues.⁴⁴ CDI is equally well measured on radiographs and MRI.⁴⁷

According to the literature, 3 different measurement methods have been used to describe degree of patella–trochlea cartilage overlap: PTI, sagittal patellofemoral engagement (SPE), and patellar articular overlap (PAO).^1,11,26

PTI uses the true articular cartilage patella–trochlea relationship for measurement of patellar height on sagittal MRI in extension (Figure 3). If the patellar tendon is fully out to length (no laxity), PTI reliably and precisely determines the exact articular correlation of PF joint and patellar height.⁶

SPE is similar to percentage of articular coverage.^1,11 Patellar overlap of the trochlea is measured on 2 different sagittal MRI images: 1 with the greatest length of patellar cartilage and 1 with the greatest length of femoral trochlear cartilage. This measurement did not correlate with CDI.¹ SPE was not evaluated in control studies, and normal and pathologic values are unavailable.

PAO is measured with patients positioned at rest and in standard knee coils.¹ MRI was not obtained in full extension or with quadriceps activation, and knee flexion angle values are unavailable. Total patellar articular length was measured on the sagittal MRI that showed the greatest patellar length and articular cartilage thickness. The same image was used to measure articular overlap, or the length of patellar cartilage overlying the trochlear cartilage, as measured parallel to the subchondral surface of the patella. PAO correlates well with conventional patellar height measurements in the sagittal plane and shows promise as a simpler alternative to the conventional indices.¹ Normal and pathologic values are unavailable.

So far, PTI is the only method that was controlled in several studies, assessed for its reliability, and compared with other patellar height measurements.^6,14

Patellar Tendon Length. PTL can be measured on lateral radiographs or sagittal MRI. Radiologic and MRI measurements are described as not significantly different⁴⁷ or slightly different, and 0.09 to 0.13 needs to be added with the ISI ratio on radiographs, MRI, and CT.⁴⁶ PTL is reliably evaluated with ISI.^41,50 There is a weak correlation of patient height and PTL: Taller people have normally longer tendons.^51-53

PTL measurements revealed that the posterior surface of the patellar tendon was significantly shorter than the anterior surface. Compared with their corresponding posterior fascicles, anterior fascicles are longer; their attachment is more proximal to the patella and more distal to the tibia. In addition, posterior PTL is significantly shorter with the posterior patellar attachment (adheres to posterior aspect of the inferior patellar pole) than with the anterior attachment (adheres to anterior aspect of the inferior patellar pole).⁵⁶ Moreover, the lateral and medial fascicles are longer than the central fascicles attaching at the most inferior patellar pole. This issue must be considered in image cut selection (Figures 6A, 6B). Furthermore, type of inferior pole of patella (pointed, intermediate, blunt) is important in measurement.⁵⁶ Overall, mean (SD) PTL was 54.9 (1.2) mm on the anterior surface and 35.0 (0.6) mm on the posterior surface.

It is important to precisely describe the measurement method and location (sagittal cut) and to consider the shape of the inferior patellar pole and the site of the patellar tendon attachment.⁵⁶

Treatments. For patella alta, the surgical treatment goals are to increase the PF contact area and improve PF articular congruence, and thereby increase PF stability.^31-33 Four different procedures were used to treat patella alta (Table 5), but only 11 of the 92 original study articles and 8 of the 28 review articles included in our review mentioned a specific patellar height that required surgical correction (Tables 5, 6). Recommendations were based on CDI (>1.2 to >1.4) and less often on ISI (>1.2 to >1.4) or PTL (>56 mm).

Tibial tubercle distalization is effective in normalizing patellar height to correct the patellar index in patella alta (Figures 7A, 7B).^{13,18,38,55,57} Tibial tubercle distalization and patellar tendon tenodesis attached to the original insertion normalize PTL and stabilize the PF joint in patients with patella alta.^5,47 In a comparison of these surgical procedures, cartilage stress was lower with distalization than with distalization and tenodesis.¹³

Soft-tissue methods are recommended in children, as bone procedures injure the proximal tibial physis and may cause it to close prematurely.⁵⁸ The patella can be distally advanced by completely mobilizing the patellar tendon and fixating with sutures through the cartilaginous tibial tubercle. This technique is a satisfactory treatment for skeletally immature patients who present with habitual patellar dislocation associated with patella alta.^58,59

CDI and BPI assess patellar height relative to the tibial plateau, and therefore are the most useful measurement methods for patellar height after distalization of the tibial tubercle.⁵ ISI does not change after distalization of the tibial tubercle and cannot be recommended.^5,18 As PF indices (eg, PTI) can trace preoperative and postoperative values, these measurements are valuable.

Controversies

Our review found no consensus on measurement method or cutoff value. No measurement method showed clear clinical or methodologic superiority. Most published patellar height and patella alta data are based on conventional radiographs using a tibial reference point, even though a femoral or even trochlear reference point seems more reproducible, particularly in PF pathologies. Several cutoff values have been reported for each patella alta measurement method. Regarding pathologic thresholds, which might require surgical correction, very little information has been published, and scientific evidence is lacking. Numerous important aspects remain unanswered after this review, and clarification is mandatory.

Five Key Facts

1. In patella alta assessment, different morphologic, biomechanical, and functional aspects must be considered. The most relevant aspect is decreased engagement of the patella and trochlea,^4-9,11,26 which results in decreased bony stability in knee extension.^1-3 Therefore, patella alta is one of the potential risk factors for patellar instability with a high percentage of recurrent patellar dislocation.^4-9 In early knee flexion, the patella translates more distally with better engagement of the patella in the trochlea and better stability. Therefore, measurement in extension, with the patellar tendon out to length, seems to offer a more reliable assessment of the patella–femur relationship.

2. Insufficient engagement of the patella in the trochlea is the most important aspect of patella alta.¹¹ Therefore, direct measurement of this engagement seems logical.

3. As radiographs do not show articular cartilage, they should not be used to assess the articular patella–femur relationship.^11,14,26 Patella–trochlea cartilage overlap is the most relevant factor for patella alta and should be measured on MRI.^6,14,26,32

4. PTL is an important factor for patellar height and particularly patella alta. The range of normal PTL values is wide: 35 mm to 61 mm. The described cutoff values for patella alta (>52 mm to >56 mm) fall within this normal range. The cause may be the different measurement methods used.^33,47,59-61 Therefore, for precise diagnostics, a standardized measurement method that includes the selected cut imaging is mandatory.

Conclusion 

Our review revealed many variations in patella alta definitions and descriptions, measurement methods, cutoff values, and treatment options. Presence of patella alta depends on measurement method used. Methods cannot be used interchangeably, and they all have their advantages and limitations. Unfortunately, there is no generally accepted consensus on measurement method, patella alta cutoff value, or treatment with ideal correction. Treatment planning and outcomes assessment require clarification of these many issues.

Take-Home Points

• Patella alta has a reduced articular area of PF contact.
• Presence of patella alta depends on the measurement method.
• Patella alta is defined as ISI >1.2 and CDI >1.2 to >1.3.
• On sagittal MRI, PTI is used most often with cutoff values of <0.125 to 0.28.
• Tibial tubercle distalization is most often used to treat patella alta. The desired postoperative patellar height is a CDI of 1.0.

Patella alta is a patella that rides abnormally high in relation to the femur, the femoral trochlea, or the tibia,¹ with decreased bony stability requiring increased knee flexion angles to engage the trochlea.^2,3 An abnormally high patella may therefore insufficiently engage the proximal trochlea groove both in extension and in the early phase of knee flexion—making it one of the potential risk factors for patellar instability.^4-10 Accordingly, patella alta is present in 30% of patients with recurrent patellar dislocation.¹¹ It also occurs in other disorders, such as knee extensor apparatus disorders, in patients with patellofemoral (PF) pain, chondromalacia, Sinding-Larsen-Johansson disease, Osgood-Schlatter disease, patellar tendinopathy, and osteoarthritis.^1,7,8,12-18 As such, patella alta represents an important predisposing factor for patellar malalignment and PF-related complaints. On the other hand, patella alta may also be a normal variant of a person’s knee anatomy and may be well tolerated when not combined with other instability factors.⁴

Despite the importance of patella alta, there is no consensus on a precise definition, the most reliable measurement method, or the factors thought to be important in clinical decisions regarding treatment. To address this issue, we systematically reviewed the patella alta literature for definitions, the most common measurement methods and their patella alta cutoff values, and cutoff values for surgical correction and proposed surgical techniques.

Methods

In February 2017, using the term patella alta, we performed a systematic literature search on PubMed. Inclusion criteria were original study or review articles, publication in peer-reviewed English-language journals between 2000 and 2017, and narrative description or measurement of human patellar height on plain radiographs or magnetic resonance imaging (MRI). Excluded were abstracts and articles in languages other than English; animal and computational/biomechanical studies; case reports; and knee arthroplasties, knee extensor ruptures, and hereditary and congenital diseases. All evidence levels were included.

We assessed measurement methods, reported cutoff values for patella alta, cutoff values for performing surgical correction, proposed surgical techniques, and postoperative target values. Original study articles and review articles were analyzed separately.

Results

Of 211 articles identified, 92 met the inclusion criteria for original study, and 28 for review. All their abstracts were reviewed, and 91 were excluded: 17 for language other than English, 11 for animal study, 12 for biomechanical/computational study, 20 for case report, 8 for arthroplasty, 13 for hereditary or congenital disease, 1 for extensor apparatus rupture, 3 for editorial letter, and 6 for other reasons. Full text copies of all included articles were obtained and reviewed.

Original Study Articles

Definition. Of the 92 original study articles, 17 (18.5%) defined patella alta by description alone, and 75 (81.5%) used imaging-based measurements. Patella alta was described as a patella that rides abnormally high in relation to the trochlear groove, with a reduced articular area of PF contact^1,15,19-21 or decreased patella–trochlea cartilage overlap.²² With this reduced contact area, there is increased PF stress.²¹

With radiographic measurements, patella alta is defined as a Caton-Deschamps index (CDI) of >1.2 to >1.3, an Insall-Salvati index (ISI) of >1.2, a Blackburne-Peel index (PBI) of >1.0,^{4,15,18,23-25} and a patellotrochlear index (PTI) of <0.125 to 0.28.^6,26

On lateral radiographs, ISI was the most common measurement (33 studies), with patella alta cutoff values ranging from >1.2 to >1.5. The second most common measurement was CDI (24 studies), with cutoff values of >1.2 to >1.3. Other indices, such as the modified ISI (6 studies), the BPI (1 study), and the Koshino index (2 studies), had their cutoff values used more consistently (>1.6 to >2.4, >1.0, and >1.2, respectively) but these indices were rarely reported in the literature (Table 1).^27,28,29 

Thirty-six studies defined patella alta with MRI using either the aforementioned radiographic ratios (23 studies, 3 indices, Table 2) or PF indices (13 studies, 4 methods, Table 3).³⁰ 

On sagittal MRI, PTI was used most often; cutoff values were <0.125 to 0.28.

Thirteen studies defined patella alta with PTL: 5 using lateral conventional radiographs and 8 using sagittal MRI. For each type of imaging, the cutoff value was >52 mm to >56 mm. PTL was measured either independently or together with ISI on sagittal MRI (Table 4).

22

Review Articles

Twenty-eight review articles met the inclusion criteria.^35-40 Patella alta was described mostly with ISI (75%) or CDI (64%). In up to 57% of these articles, a patella alta reference value was missing. Only 1 article mentioned different cutoff values for conventional radiographs and MRI. BPI was mentioned in 50% of studies, but only 2 indicated a cutoff value for patella alta. Eleven percent used PTI on sagittal MRI and took patella–trochlea cartilage overlap into account.

Eight review articles mentioned cutoff values for surgical correction. Only 1 of 4 articles mentioned a cutoff value for correcting patella alta in PF instability, and only 2 articles suggested an ideal postoperative patellar height (Table 6).

No review article relied on PTL to describe patella alta or to advise surgical treatment.

Discussion 

Our review revealed many variations in patella alta definitions and descriptions, measurement methods, cutoff values, and treatment options. Interpretation of patellar height and, particularly, patella alta is very heterogeneous. Accordingly, comparing surgical indications, surgical treatment options, and outcomes across studies can be difficult.

Measurement Methods

Radiographs. Conventional radiographs were used to describe patella alta in two-thirds of the original study articles. The most common measurement methods marked the position of the patella relative to either the femur (direct assessment) or the tibia (indirect assessment).^14,25 All established measurement methods use lateral radiographs, which do not show articular cartilage.^11,14 Therefore, lateral radiograph ratios of different and variable bony landmarks do not measure actual PF articular congruence. The widely variable morphologies of patella (distal patellar nose, different articulating surface), femoral trochlea (facet in height and length), proximal tibia (inherited or acquired deformities on tibial tubercle), and slope are all confounding factors that may affect measurement (Figure 1). In addition, specific variations in PF joint morphology (eg, small patellar articular surface, short trochlea) are not well represented by these ratios.¹¹

All these methods have advantages, limitations, and different values of interobserver and intraobserver variability, reliability, and reproducibility (Table 7).^29,41

Determination of both patellar height and patella alta depends on the measurement method used and is significantly affected by anatomical variants, such as extra-articular patella and femorotibial landmarks. 

The ISI method is most commonly used because it does not depend on degree of knee flexion, is thought to measure the relative length of the patellar tendon the best,⁵ and has established MRI criteria.⁶ However, ISI has limitations: Its distal bony landmark is the tibial tuberosity, which can be difficult to assess¹⁴; the shape of the patella (mainly its inferior point) varies⁴²; and the measurement does not change after distalization of the tibial tubercle.⁵

CDI is the most accurate diagnostic method because it relies on readily identifiable and reproducible anatomical landmarks; does not depend on radiograph quality, knee size, radiologic enlargement, or position of the tibial tubercle or patellar modification; and is unaffected by degree of knee flexion between 10° and 80°.^38,43 CDI is the method that is most useful in describing patellar height after distalization of the tibial tubercle because it assesses the height of the patella relative to the tibial plateau.⁵ CDI is limited with respect to clear identification of the patellar and tibial articular margin.³⁷

BPI has the lowest interobserver variability and discriminates best among patella alta, norma, and infera.⁴¹ Like CDI, BPI assesses patellar height relative to the tibial plateau, and thus is useful in describing patellar height after distalization of the tibial tubercle.⁵ BPI is limited in that it uses a line drawn along the tibial plateau, where variations in inclination and tibial slope produce inaccuracies,¹⁴ and depends highly on projection angles. Clinically, BPI is rarely used.

As the literature shows, the radiologic methods of determining patellar height are variable and unreliable and depend on the ratio used.^26,41 These methods do not reveal precise information about the PF articular congruence, the key finding for necessary treatment.

Radiographic Indices on MRI. Some studies measured radiographic indices on sagittal MRI. Radiologic and MRI measurements are described as not significantly different or slightly different, and 0.09 to 0.13 needs to be added with ISI and BP ratios on radiographs, MRI, and computed tomography (CT).^17,44-47 ISI is commonly used, and its clinical application is easy. Although classically measured on plain radiographs, ISI is reliably measured on MRI as well.^17,30 The traditional 1.2 threshold for defining patella alta was used by Charles and colleagues.⁴⁴ CDI is equally well measured on radiographs and MRI.⁴⁷

According to the literature, 3 different measurement methods have been used to describe degree of patella–trochlea cartilage overlap: PTI, sagittal patellofemoral engagement (SPE), and patellar articular overlap (PAO).^1,11,26

PTI uses the true articular cartilage patella–trochlea relationship for measurement of patellar height on sagittal MRI in extension (Figure 3). If the patellar tendon is fully out to length (no laxity), PTI reliably and precisely determines the exact articular correlation of PF joint and patellar height.⁶

SPE is similar to percentage of articular coverage.^1,11 Patellar overlap of the trochlea is measured on 2 different sagittal MRI images: 1 with the greatest length of patellar cartilage and 1 with the greatest length of femoral trochlear cartilage. This measurement did not correlate with CDI.¹ SPE was not evaluated in control studies, and normal and pathologic values are unavailable.

PAO is measured with patients positioned at rest and in standard knee coils.¹ MRI was not obtained in full extension or with quadriceps activation, and knee flexion angle values are unavailable. Total patellar articular length was measured on the sagittal MRI that showed the greatest patellar length and articular cartilage thickness. The same image was used to measure articular overlap, or the length of patellar cartilage overlying the trochlear cartilage, as measured parallel to the subchondral surface of the patella. PAO correlates well with conventional patellar height measurements in the sagittal plane and shows promise as a simpler alternative to the conventional indices.¹ Normal and pathologic values are unavailable.

So far, PTI is the only method that was controlled in several studies, assessed for its reliability, and compared with other patellar height measurements.^6,14

Patellar Tendon Length. PTL can be measured on lateral radiographs or sagittal MRI. Radiologic and MRI measurements are described as not significantly different⁴⁷ or slightly different, and 0.09 to 0.13 needs to be added with the ISI ratio on radiographs, MRI, and CT.⁴⁶ PTL is reliably evaluated with ISI.^41,50 There is a weak correlation of patient height and PTL: Taller people have normally longer tendons.^51-53

PTL measurements revealed that the posterior surface of the patellar tendon was significantly shorter than the anterior surface. Compared with their corresponding posterior fascicles, anterior fascicles are longer; their attachment is more proximal to the patella and more distal to the tibia. In addition, posterior PTL is significantly shorter with the posterior patellar attachment (adheres to posterior aspect of the inferior patellar pole) than with the anterior attachment (adheres to anterior aspect of the inferior patellar pole).⁵⁶ Moreover, the lateral and medial fascicles are longer than the central fascicles attaching at the most inferior patellar pole. This issue must be considered in image cut selection (Figures 6A, 6B). Furthermore, type of inferior pole of patella (pointed, intermediate, blunt) is important in measurement.⁵⁶ Overall, mean (SD) PTL was 54.9 (1.2) mm on the anterior surface and 35.0 (0.6) mm on the posterior surface.

It is important to precisely describe the measurement method and location (sagittal cut) and to consider the shape of the inferior patellar pole and the site of the patellar tendon attachment.⁵⁶

Treatments. For patella alta, the surgical treatment goals are to increase the PF contact area and improve PF articular congruence, and thereby increase PF stability.^31-33 Four different procedures were used to treat patella alta (Table 5), but only 11 of the 92 original study articles and 8 of the 28 review articles included in our review mentioned a specific patellar height that required surgical correction (Tables 5, 6). Recommendations were based on CDI (>1.2 to >1.4) and less often on ISI (>1.2 to >1.4) or PTL (>56 mm).

Tibial tubercle distalization is effective in normalizing patellar height to correct the patellar index in patella alta (Figures 7A, 7B).^{13,18,38,55,57} Tibial tubercle distalization and patellar tendon tenodesis attached to the original insertion normalize PTL and stabilize the PF joint in patients with patella alta.^5,47 In a comparison of these surgical procedures, cartilage stress was lower with distalization than with distalization and tenodesis.¹³

Soft-tissue methods are recommended in children, as bone procedures injure the proximal tibial physis and may cause it to close prematurely.⁵⁸ The patella can be distally advanced by completely mobilizing the patellar tendon and fixating with sutures through the cartilaginous tibial tubercle. This technique is a satisfactory treatment for skeletally immature patients who present with habitual patellar dislocation associated with patella alta.^58,59

CDI and BPI assess patellar height relative to the tibial plateau, and therefore are the most useful measurement methods for patellar height after distalization of the tibial tubercle.⁵ ISI does not change after distalization of the tibial tubercle and cannot be recommended.^5,18 As PF indices (eg, PTI) can trace preoperative and postoperative values, these measurements are valuable.

Controversies

Our review found no consensus on measurement method or cutoff value. No measurement method showed clear clinical or methodologic superiority. Most published patellar height and patella alta data are based on conventional radiographs using a tibial reference point, even though a femoral or even trochlear reference point seems more reproducible, particularly in PF pathologies. Several cutoff values have been reported for each patella alta measurement method. Regarding pathologic thresholds, which might require surgical correction, very little information has been published, and scientific evidence is lacking. Numerous important aspects remain unanswered after this review, and clarification is mandatory.

Five Key Facts

1. In patella alta assessment, different morphologic, biomechanical, and functional aspects must be considered. The most relevant aspect is decreased engagement of the patella and trochlea,^4-9,11,26 which results in decreased bony stability in knee extension.^1-3 Therefore, patella alta is one of the potential risk factors for patellar instability with a high percentage of recurrent patellar dislocation.^4-9 In early knee flexion, the patella translates more distally with better engagement of the patella in the trochlea and better stability. Therefore, measurement in extension, with the patellar tendon out to length, seems to offer a more reliable assessment of the patella–femur relationship.

2. Insufficient engagement of the patella in the trochlea is the most important aspect of patella alta.¹¹ Therefore, direct measurement of this engagement seems logical.

3. As radiographs do not show articular cartilage, they should not be used to assess the articular patella–femur relationship.^11,14,26 Patella–trochlea cartilage overlap is the most relevant factor for patella alta and should be measured on MRI.^6,14,26,32

4. PTL is an important factor for patellar height and particularly patella alta. The range of normal PTL values is wide: 35 mm to 61 mm. The described cutoff values for patella alta (>52 mm to >56 mm) fall within this normal range. The cause may be the different measurement methods used.^33,47,59-61 Therefore, for precise diagnostics, a standardized measurement method that includes the selected cut imaging is mandatory.

Conclusion 

Our review revealed many variations in patella alta definitions and descriptions, measurement methods, cutoff values, and treatment options. Presence of patella alta depends on measurement method used. Methods cannot be used interchangeably, and they all have their advantages and limitations. Unfortunately, there is no generally accepted consensus on measurement method, patella alta cutoff value, or treatment with ideal correction. Treatment planning and outcomes assessment require clarification of these many issues.

Take-Home Points

• There is no difference in PROMs following knotless or knotted labral repair.
• Operative time is shorter for knotless compared to knotted glenoid labral tears.
• Knotless constructs may be more predictable than knotted constructs biomechanically.

Orthopedic surgeons often encounter labral pathology, and labral tears historically have required open techniques.^1-3 Arthroscopy allows for advanced visualization and treatment of shoulder lesions,^4,5 including anterior, posterior, and superior labrum anterior to posterior (SLAP) lesions.⁶

The goal of arthroscopic labral repair is to restore joint stability while maintaining range of motion. Arthroscopically repairing the labrum with suture anchors has become the standard technique, and several studies have reported satisfactory biomechanical and clinical results.^1,7-12 Surgeons traditionally have been required to tie knots for these anchors, but knot security varies significantly among experienced arthroscopic surgeons.¹³ In addition, knots can migrate,¹⁴ and bulky knots can cause chondral abrasion.^15,16 Several manufacturers have introduced knotless anchors for soft-tissue fixation.^15,17 The knotless technique provides a low-profile repair with potentially less operating time.⁸ These factors may warrant switching from knotted to knotless techniques if outcomes are clinically acceptable. However, few studies have compared knotted and knotless techniques for glenohumeral labral repair.^8,15,18-21

We conducted a study to compare the clinical results and operative times of knotless and knotted fixation of anterior and posterior glenohumeral labral repairs and SLAP repairs. We hypothesized there would be no difference in patient-reported outcome measures (PROMs) between knotted and knotless techniques.

Methods

We retrospectively evaluated data that had been prospectively collected between 2012 and 2016 in a Surgical Outcomes System (SOS; Arthrex) database. Participation in this registry is elective, and enrollment can occur on a case-by-case basis. The database stores data on basic demographics, PROMs, and operative time. Data for our specific analysis were available for surgeries performed by 115 different surgeons. Inclusion criteria included primary isolated arthroscopic anterior, isolated posterior, and isolated SLAP repair with completely knotted or completely knotless labral repair and minimum 1-year follow-up. Exclusion criteria included hybrid knotted–knotless repair, rotator cuff repair, revision surgery, open surgery, and lack of complete follow-up data.

SOS is a proprietary registry that allows for the collection of basic patient demographics, diagnostic and operative data, and PROMs. PROMs in the SOS shoulder arthroscopy module include Veterans RAND 12-Item Health Survey (VR-12) mental health and physical health component summary scores, visual analog scale (VAS) pain scores, and American Shoulder and Elbow Surgeons (ASES) scores. For this study, PROMs were reviewed before surgery and 6 and 12 months after surgery. In addition, operative times of all procedures were collected.

For the analysis, completely knotted and completely knotless techniques were compared for anterior repair, posterior repair, and SLAP repair. A t test was used to compare the techniques on PROMs, and χ2 test was used to evaluate proportion differences. Statistical significance was set at P < .05. 

Results

Anterior Labral Repairs

Of the 102 knotted anterior labral repairs that met the study criteria, 26 (25%) had minimum 1-year follow-up. Of the 122 knotless labral repairs, 33 (27%) had minimum 1-year follow-up. Seventy-five percent of knotted repairs and 80% of knotless repairs were performed in men. Mean (SD) age was 25.3 (11.7) years for the knotted group and 26.9 (10.6) years for the knotless group (P = .109). Anterior labral repairs did not differ in PROMs at any point (Table 1).

A mean of 2.8 anchors was used for knotted repairs, and a mean of 3.1 anchors was used for knotless repairs. Mean operative time was 75.8 minutes for knotted repairs and 67.5 minutes for knotless repairs. Mean (SD) time per anchor was 30.9 (13.9) minutes for knotted repairs and 25.6 (19.5) minutes for knotless repairs (P = .021). 

Posterior Labral Repairs

Of the 165 knotted posterior labral repairs that met the study criteria, 39 (29%) had minimum 1-year follow-up. Of the 229 knotless labral repairs, 56 (24%) had minimum 1-year follow-up. Eighty-five percent of knotted repairs and 74% of knotless repairs were performed in men. Mean (SD) age was 29.1 (12.0) years for the knotted group and 27.5 (11.9) years for the knotless group (P = .148). Posterior labral repairs did not differ in PROMs before surgery or 1 year after surgery; 6 months after surgery, these repairs differed only in ASES scores (Table 2). 

A mean of 3.6 anchors was used for knotted repairs, and a mean of 3.0 anchors was used for knotless repairs. Mean operative time was 67.0 minutes for knotted repairs and 43.1 minutes for knotless repairs. Mean (SD) time per anchor was 21.1 (10.7) minutes for knotted repairs and 17.5 (14.7) minutes for knotless repairs (P = .031).

SLAP Repairs

Of the 54 knotted SLAP repairs that met the study criteria, 24 (44%) had minimum 1-year follow-up. Of the 138 knotless SLAP repairs, 48 (35%) had minimum 1-year follow-up. Seventy-two percent of knotted repairs and 72% of knotless repairs were performed in men. Mean (SD) age was 32.1 (11.6) years for the knotted group and 35.0 (12.8) years for the knotless group (P = .246). SLAP repairs did not differ in PROMs at any point (Table 3).

A mean of 1.9 anchors was used for knotted repairs, and a mean of 2.1 anchors was used for knotless repairs. Mean operative time was 59.0 minutes for knotted repairs and 40.9 minutes for knotless repairs. Mean (SD) time per anchor was 36.6 (22.4) minutes for knotted repairs and 26.3 (14.0) minutes for knotless repairs (P = .080).

Discussion

Our hypothesis that there would be no difference in PROMs between knotted and knotless labral repairs was confirmed. Our findings are important because this study compared the gold standard of knotted suture anchor with the alternative knotless suture anchor in glenohumeral labral repair. These findings have several important implications for labral repair.

Knot tying traditionally has been used to achieve fixation with an anchor. Although simple in concept, knot tying can be challenging and its quality variable. Thal¹⁵ wrote that good-quality arthroscopic suture anchor repair is difficult to achieve because satisfactory knot tying requires significant practice with certain devices designed specifically for knot tying. Multiple surgeons have noted a significant learning curve associated with knot tying, and there is no agreement on which knot is superior.^22-26 Leedle and Miller¹⁷ even suggested that, because knot tying is difficult, tying knots arthroscopically can lead to knot failure. In their study, they concluded that the knot is consistently the weakest link in suture repair of an anterior labrum construct. In a controlled laboratory study, Hanypsiak and colleagues¹³ found considerable knot-strength variability among expert arthroscopists. Only 65 (18%) of 365 knots tied fell within 20% of the mean for ultimate load failure, and only 128 (36%) of 365 fell within 20% of the mean for clinical failure (3 mm of displacement). These data suggested expert arthroscopists were unable to tie 5 consecutive knots of the same type consistently. Even among experts, it seems, knot strength varies significantly, and knot-strength issues may affect the rates of labral repair failure.

Multiple authors have also reported that bulky knots can cause chondral abrasion or that knots can migrate.^25,27 Rhee and Ha²⁷ reported that, when another knot (eg, a half-hitch knot) is tied to prevent knot failure, the resulting overall knot can be too bulky for a limited space, and chondral abrasion can result. In addition, regardless of size, a knot can migrate and, in its new position, start rubbing against the head of the humerus. Kim and colleagues¹⁴ found that, even when a knot is placed away from the humeral head, migration and repeated contact with the head are possible. Park and colleagues²⁸ found that a significant number of knotted SLAP repairs required arthroscopic knot removal for relief of knot-induced pain and clicking.

Knotless constructs have several theoretical advantages over knotted constructs. Compared with a knotted technique, a knotless technique appears to provide more predictable strength, as variability in knot tying is eliminated (unpublished data). A knotless repair also has a lower profile,8 which should lead to less contact with the humeral head.¹⁹ Last, a knotless repair is more efficient—it takes less time to perform. In our study, operative time was reduced by a mean of 5.3 minutes per anchor for anterior labral repair. Assuming a mean of 3 anchors, this reduction equates to 16 minutes per case. Therefore, a surgeon who performs 25 labral repairs a year can save 6.7 hours a year. Reduced operative time benefits the patient (ie, lower risk of infection and other complications²⁹), the surgeon, and the healthcare system (ie, cost savings). Macario³⁰ found that operating room costs averaged $62 per minute (range, $22-$133 per minute). Therefore, saving 16 minutes per case could lead to saving $992 per case. In summary, a knotless technique appears to be clinically and financially advantageous as long as its results are the same as or better than those of a knotted technique.

A few other studies have compared knotted and knotless techniques. In a cadaveric study, Slabaugh and colleagues²⁰ found no difference in labral height between traditional and knotless suture anchors. Leedle and Miller¹⁷ found that knotless constructs are biomechanically stronger than knotted constructs in anterior labral repair. In a level 3 clinical study, Yang and colleagues²¹ compared a conventional vertical knot with a knotless horizontal mattress suture in 41 patients who underwent SLAP repair. Functional outcome was no different between the 2 groups, but postoperative range of motion was improved in the knotless group. Ng and Kumar³¹ compared 45 patients who had knotted Bankart repair with 42 patients who had knotless Bankart repair and found no difference in functional outcome or rate of recurrent dislocation. Similarly, Kocaoglu and colleagues²² found no difference in recurrence rate between 18 patients who underwent a knotted technique for arthroscopic Bankart repair and 20 patients who underwent a knotless technique. Our findings corroborate the findings of these studies and further support the idea that there is no difference between knotted and knotless constructs with respect to PROMs.

Study Limitations

The major strength of this study was its large cohort and large population of surgeons. However, there were several study limitations. First, we could not detail specific repair techniques, such as simple or horizontal mattress orientation, and rehabilitation protocols and other variables are likely as well. Second, the repair technique was not randomized, and therefore there may have been a selection bias based on tissue quality. Although we cannot prove no bias, we think it was unlikely given that the groups were similar in age. Third, our data did not include information on range of motion or recurrent instability. Our goal was simply to evaluate PROMs among multiple surgeons using the 2 techniques. Fourth, there was substantial follow-up loss, which introduced potential selection bias. Last, there may have been conditions under which a hybrid technique with inferior knot tying, combined with a hybrid knotless construct, could have proved advantageous.

Conclusion

Our data showed that the advantages of knotless repair are not compromised in clinical situations. Although the data showed no significant difference in clinical outcomes, knotless repairs may provide surgeons with shorter surgeries, simpler constructs, less potential for chondral damage, and more consistent suture tensioning. Additional studies may further confirm these results.

Take-Home Points

• There is no difference in PROMs following knotless or knotted labral repair.
• Operative time is shorter for knotless compared to knotted glenoid labral tears.
• Knotless constructs may be more predictable than knotted constructs biomechanically.

Orthopedic surgeons often encounter labral pathology, and labral tears historically have required open techniques.^1-3 Arthroscopy allows for advanced visualization and treatment of shoulder lesions,^4,5 including anterior, posterior, and superior labrum anterior to posterior (SLAP) lesions.⁶

The goal of arthroscopic labral repair is to restore joint stability while maintaining range of motion. Arthroscopically repairing the labrum with suture anchors has become the standard technique, and several studies have reported satisfactory biomechanical and clinical results.^1,7-12 Surgeons traditionally have been required to tie knots for these anchors, but knot security varies significantly among experienced arthroscopic surgeons.¹³ In addition, knots can migrate,¹⁴ and bulky knots can cause chondral abrasion.^15,16 Several manufacturers have introduced knotless anchors for soft-tissue fixation.^15,17 The knotless technique provides a low-profile repair with potentially less operating time.⁸ These factors may warrant switching from knotted to knotless techniques if outcomes are clinically acceptable. However, few studies have compared knotted and knotless techniques for glenohumeral labral repair.^8,15,18-21

We conducted a study to compare the clinical results and operative times of knotless and knotted fixation of anterior and posterior glenohumeral labral repairs and SLAP repairs. We hypothesized there would be no difference in patient-reported outcome measures (PROMs) between knotted and knotless techniques.

Methods

We retrospectively evaluated data that had been prospectively collected between 2012 and 2016 in a Surgical Outcomes System (SOS; Arthrex) database. Participation in this registry is elective, and enrollment can occur on a case-by-case basis. The database stores data on basic demographics, PROMs, and operative time. Data for our specific analysis were available for surgeries performed by 115 different surgeons. Inclusion criteria included primary isolated arthroscopic anterior, isolated posterior, and isolated SLAP repair with completely knotted or completely knotless labral repair and minimum 1-year follow-up. Exclusion criteria included hybrid knotted–knotless repair, rotator cuff repair, revision surgery, open surgery, and lack of complete follow-up data.

SOS is a proprietary registry that allows for the collection of basic patient demographics, diagnostic and operative data, and PROMs. PROMs in the SOS shoulder arthroscopy module include Veterans RAND 12-Item Health Survey (VR-12) mental health and physical health component summary scores, visual analog scale (VAS) pain scores, and American Shoulder and Elbow Surgeons (ASES) scores. For this study, PROMs were reviewed before surgery and 6 and 12 months after surgery. In addition, operative times of all procedures were collected.

For the analysis, completely knotted and completely knotless techniques were compared for anterior repair, posterior repair, and SLAP repair. A t test was used to compare the techniques on PROMs, and χ2 test was used to evaluate proportion differences. Statistical significance was set at P < .05. 

Results

Anterior Labral Repairs

Of the 102 knotted anterior labral repairs that met the study criteria, 26 (25%) had minimum 1-year follow-up. Of the 122 knotless labral repairs, 33 (27%) had minimum 1-year follow-up. Seventy-five percent of knotted repairs and 80% of knotless repairs were performed in men. Mean (SD) age was 25.3 (11.7) years for the knotted group and 26.9 (10.6) years for the knotless group (P = .109). Anterior labral repairs did not differ in PROMs at any point (Table 1).

A mean of 2.8 anchors was used for knotted repairs, and a mean of 3.1 anchors was used for knotless repairs. Mean operative time was 75.8 minutes for knotted repairs and 67.5 minutes for knotless repairs. Mean (SD) time per anchor was 30.9 (13.9) minutes for knotted repairs and 25.6 (19.5) minutes for knotless repairs (P = .021). 

Posterior Labral Repairs

Of the 165 knotted posterior labral repairs that met the study criteria, 39 (29%) had minimum 1-year follow-up. Of the 229 knotless labral repairs, 56 (24%) had minimum 1-year follow-up. Eighty-five percent of knotted repairs and 74% of knotless repairs were performed in men. Mean (SD) age was 29.1 (12.0) years for the knotted group and 27.5 (11.9) years for the knotless group (P = .148). Posterior labral repairs did not differ in PROMs before surgery or 1 year after surgery; 6 months after surgery, these repairs differed only in ASES scores (Table 2). 

A mean of 3.6 anchors was used for knotted repairs, and a mean of 3.0 anchors was used for knotless repairs. Mean operative time was 67.0 minutes for knotted repairs and 43.1 minutes for knotless repairs. Mean (SD) time per anchor was 21.1 (10.7) minutes for knotted repairs and 17.5 (14.7) minutes for knotless repairs (P = .031).

SLAP Repairs

Of the 54 knotted SLAP repairs that met the study criteria, 24 (44%) had minimum 1-year follow-up. Of the 138 knotless SLAP repairs, 48 (35%) had minimum 1-year follow-up. Seventy-two percent of knotted repairs and 72% of knotless repairs were performed in men. Mean (SD) age was 32.1 (11.6) years for the knotted group and 35.0 (12.8) years for the knotless group (P = .246). SLAP repairs did not differ in PROMs at any point (Table 3).

A mean of 1.9 anchors was used for knotted repairs, and a mean of 2.1 anchors was used for knotless repairs. Mean operative time was 59.0 minutes for knotted repairs and 40.9 minutes for knotless repairs. Mean (SD) time per anchor was 36.6 (22.4) minutes for knotted repairs and 26.3 (14.0) minutes for knotless repairs (P = .080).

Discussion

Our hypothesis that there would be no difference in PROMs between knotted and knotless labral repairs was confirmed. Our findings are important because this study compared the gold standard of knotted suture anchor with the alternative knotless suture anchor in glenohumeral labral repair. These findings have several important implications for labral repair.

Knot tying traditionally has been used to achieve fixation with an anchor. Although simple in concept, knot tying can be challenging and its quality variable. Thal¹⁵ wrote that good-quality arthroscopic suture anchor repair is difficult to achieve because satisfactory knot tying requires significant practice with certain devices designed specifically for knot tying. Multiple surgeons have noted a significant learning curve associated with knot tying, and there is no agreement on which knot is superior.^22-26 Leedle and Miller¹⁷ even suggested that, because knot tying is difficult, tying knots arthroscopically can lead to knot failure. In their study, they concluded that the knot is consistently the weakest link in suture repair of an anterior labrum construct. In a controlled laboratory study, Hanypsiak and colleagues¹³ found considerable knot-strength variability among expert arthroscopists. Only 65 (18%) of 365 knots tied fell within 20% of the mean for ultimate load failure, and only 128 (36%) of 365 fell within 20% of the mean for clinical failure (3 mm of displacement). These data suggested expert arthroscopists were unable to tie 5 consecutive knots of the same type consistently. Even among experts, it seems, knot strength varies significantly, and knot-strength issues may affect the rates of labral repair failure.

Multiple authors have also reported that bulky knots can cause chondral abrasion or that knots can migrate.^25,27 Rhee and Ha²⁷ reported that, when another knot (eg, a half-hitch knot) is tied to prevent knot failure, the resulting overall knot can be too bulky for a limited space, and chondral abrasion can result. In addition, regardless of size, a knot can migrate and, in its new position, start rubbing against the head of the humerus. Kim and colleagues¹⁴ found that, even when a knot is placed away from the humeral head, migration and repeated contact with the head are possible. Park and colleagues²⁸ found that a significant number of knotted SLAP repairs required arthroscopic knot removal for relief of knot-induced pain and clicking.

Knotless constructs have several theoretical advantages over knotted constructs. Compared with a knotted technique, a knotless technique appears to provide more predictable strength, as variability in knot tying is eliminated (unpublished data). A knotless repair also has a lower profile,8 which should lead to less contact with the humeral head.¹⁹ Last, a knotless repair is more efficient—it takes less time to perform. In our study, operative time was reduced by a mean of 5.3 minutes per anchor for anterior labral repair. Assuming a mean of 3 anchors, this reduction equates to 16 minutes per case. Therefore, a surgeon who performs 25 labral repairs a year can save 6.7 hours a year. Reduced operative time benefits the patient (ie, lower risk of infection and other complications²⁹), the surgeon, and the healthcare system (ie, cost savings). Macario³⁰ found that operating room costs averaged $62 per minute (range, $22-$133 per minute). Therefore, saving 16 minutes per case could lead to saving $992 per case. In summary, a knotless technique appears to be clinically and financially advantageous as long as its results are the same as or better than those of a knotted technique.

A few other studies have compared knotted and knotless techniques. In a cadaveric study, Slabaugh and colleagues²⁰ found no difference in labral height between traditional and knotless suture anchors. Leedle and Miller¹⁷ found that knotless constructs are biomechanically stronger than knotted constructs in anterior labral repair. In a level 3 clinical study, Yang and colleagues²¹ compared a conventional vertical knot with a knotless horizontal mattress suture in 41 patients who underwent SLAP repair. Functional outcome was no different between the 2 groups, but postoperative range of motion was improved in the knotless group. Ng and Kumar³¹ compared 45 patients who had knotted Bankart repair with 42 patients who had knotless Bankart repair and found no difference in functional outcome or rate of recurrent dislocation. Similarly, Kocaoglu and colleagues²² found no difference in recurrence rate between 18 patients who underwent a knotted technique for arthroscopic Bankart repair and 20 patients who underwent a knotless technique. Our findings corroborate the findings of these studies and further support the idea that there is no difference between knotted and knotless constructs with respect to PROMs.

Study Limitations

The major strength of this study was its large cohort and large population of surgeons. However, there were several study limitations. First, we could not detail specific repair techniques, such as simple or horizontal mattress orientation, and rehabilitation protocols and other variables are likely as well. Second, the repair technique was not randomized, and therefore there may have been a selection bias based on tissue quality. Although we cannot prove no bias, we think it was unlikely given that the groups were similar in age. Third, our data did not include information on range of motion or recurrent instability. Our goal was simply to evaluate PROMs among multiple surgeons using the 2 techniques. Fourth, there was substantial follow-up loss, which introduced potential selection bias. Last, there may have been conditions under which a hybrid technique with inferior knot tying, combined with a hybrid knotless construct, could have proved advantageous.

Conclusion

Our data showed that the advantages of knotless repair are not compromised in clinical situations. Although the data showed no significant difference in clinical outcomes, knotless repairs may provide surgeons with shorter surgeries, simpler constructs, less potential for chondral damage, and more consistent suture tensioning. Additional studies may further confirm these results.

Take-Home Points

• There is no difference in PROMs following knotless or knotted labral repair.
• Operative time is shorter for knotless compared to knotted glenoid labral tears.
• Knotless constructs may be more predictable than knotted constructs biomechanically.

Orthopedic surgeons often encounter labral pathology, and labral tears historically have required open techniques.^1-3 Arthroscopy allows for advanced visualization and treatment of shoulder lesions,^4,5 including anterior, posterior, and superior labrum anterior to posterior (SLAP) lesions.⁶

The goal of arthroscopic labral repair is to restore joint stability while maintaining range of motion. Arthroscopically repairing the labrum with suture anchors has become the standard technique, and several studies have reported satisfactory biomechanical and clinical results.^1,7-12 Surgeons traditionally have been required to tie knots for these anchors, but knot security varies significantly among experienced arthroscopic surgeons.¹³ In addition, knots can migrate,¹⁴ and bulky knots can cause chondral abrasion.^15,16 Several manufacturers have introduced knotless anchors for soft-tissue fixation.^15,17 The knotless technique provides a low-profile repair with potentially less operating time.⁸ These factors may warrant switching from knotted to knotless techniques if outcomes are clinically acceptable. However, few studies have compared knotted and knotless techniques for glenohumeral labral repair.^8,15,18-21

We conducted a study to compare the clinical results and operative times of knotless and knotted fixation of anterior and posterior glenohumeral labral repairs and SLAP repairs. We hypothesized there would be no difference in patient-reported outcome measures (PROMs) between knotted and knotless techniques.

Methods

We retrospectively evaluated data that had been prospectively collected between 2012 and 2016 in a Surgical Outcomes System (SOS; Arthrex) database. Participation in this registry is elective, and enrollment can occur on a case-by-case basis. The database stores data on basic demographics, PROMs, and operative time. Data for our specific analysis were available for surgeries performed by 115 different surgeons. Inclusion criteria included primary isolated arthroscopic anterior, isolated posterior, and isolated SLAP repair with completely knotted or completely knotless labral repair and minimum 1-year follow-up. Exclusion criteria included hybrid knotted–knotless repair, rotator cuff repair, revision surgery, open surgery, and lack of complete follow-up data.

SOS is a proprietary registry that allows for the collection of basic patient demographics, diagnostic and operative data, and PROMs. PROMs in the SOS shoulder arthroscopy module include Veterans RAND 12-Item Health Survey (VR-12) mental health and physical health component summary scores, visual analog scale (VAS) pain scores, and American Shoulder and Elbow Surgeons (ASES) scores. For this study, PROMs were reviewed before surgery and 6 and 12 months after surgery. In addition, operative times of all procedures were collected.

For the analysis, completely knotted and completely knotless techniques were compared for anterior repair, posterior repair, and SLAP repair. A t test was used to compare the techniques on PROMs, and χ2 test was used to evaluate proportion differences. Statistical significance was set at P < .05. 

Results

Anterior Labral Repairs

Of the 102 knotted anterior labral repairs that met the study criteria, 26 (25%) had minimum 1-year follow-up. Of the 122 knotless labral repairs, 33 (27%) had minimum 1-year follow-up. Seventy-five percent of knotted repairs and 80% of knotless repairs were performed in men. Mean (SD) age was 25.3 (11.7) years for the knotted group and 26.9 (10.6) years for the knotless group (P = .109). Anterior labral repairs did not differ in PROMs at any point (Table 1).

A mean of 2.8 anchors was used for knotted repairs, and a mean of 3.1 anchors was used for knotless repairs. Mean operative time was 75.8 minutes for knotted repairs and 67.5 minutes for knotless repairs. Mean (SD) time per anchor was 30.9 (13.9) minutes for knotted repairs and 25.6 (19.5) minutes for knotless repairs (P = .021). 

Posterior Labral Repairs

Of the 165 knotted posterior labral repairs that met the study criteria, 39 (29%) had minimum 1-year follow-up. Of the 229 knotless labral repairs, 56 (24%) had minimum 1-year follow-up. Eighty-five percent of knotted repairs and 74% of knotless repairs were performed in men. Mean (SD) age was 29.1 (12.0) years for the knotted group and 27.5 (11.9) years for the knotless group (P = .148). Posterior labral repairs did not differ in PROMs before surgery or 1 year after surgery; 6 months after surgery, these repairs differed only in ASES scores (Table 2). 

A mean of 3.6 anchors was used for knotted repairs, and a mean of 3.0 anchors was used for knotless repairs. Mean operative time was 67.0 minutes for knotted repairs and 43.1 minutes for knotless repairs. Mean (SD) time per anchor was 21.1 (10.7) minutes for knotted repairs and 17.5 (14.7) minutes for knotless repairs (P = .031).

SLAP Repairs

Of the 54 knotted SLAP repairs that met the study criteria, 24 (44%) had minimum 1-year follow-up. Of the 138 knotless SLAP repairs, 48 (35%) had minimum 1-year follow-up. Seventy-two percent of knotted repairs and 72% of knotless repairs were performed in men. Mean (SD) age was 32.1 (11.6) years for the knotted group and 35.0 (12.8) years for the knotless group (P = .246). SLAP repairs did not differ in PROMs at any point (Table 3).

A mean of 1.9 anchors was used for knotted repairs, and a mean of 2.1 anchors was used for knotless repairs. Mean operative time was 59.0 minutes for knotted repairs and 40.9 minutes for knotless repairs. Mean (SD) time per anchor was 36.6 (22.4) minutes for knotted repairs and 26.3 (14.0) minutes for knotless repairs (P = .080).

Discussion

Our hypothesis that there would be no difference in PROMs between knotted and knotless labral repairs was confirmed. Our findings are important because this study compared the gold standard of knotted suture anchor with the alternative knotless suture anchor in glenohumeral labral repair. These findings have several important implications for labral repair.

Knot tying traditionally has been used to achieve fixation with an anchor. Although simple in concept, knot tying can be challenging and its quality variable. Thal¹⁵ wrote that good-quality arthroscopic suture anchor repair is difficult to achieve because satisfactory knot tying requires significant practice with certain devices designed specifically for knot tying. Multiple surgeons have noted a significant learning curve associated with knot tying, and there is no agreement on which knot is superior.^22-26 Leedle and Miller¹⁷ even suggested that, because knot tying is difficult, tying knots arthroscopically can lead to knot failure. In their study, they concluded that the knot is consistently the weakest link in suture repair of an anterior labrum construct. In a controlled laboratory study, Hanypsiak and colleagues¹³ found considerable knot-strength variability among expert arthroscopists. Only 65 (18%) of 365 knots tied fell within 20% of the mean for ultimate load failure, and only 128 (36%) of 365 fell within 20% of the mean for clinical failure (3 mm of displacement). These data suggested expert arthroscopists were unable to tie 5 consecutive knots of the same type consistently. Even among experts, it seems, knot strength varies significantly, and knot-strength issues may affect the rates of labral repair failure.

Multiple authors have also reported that bulky knots can cause chondral abrasion or that knots can migrate.^25,27 Rhee and Ha²⁷ reported that, when another knot (eg, a half-hitch knot) is tied to prevent knot failure, the resulting overall knot can be too bulky for a limited space, and chondral abrasion can result. In addition, regardless of size, a knot can migrate and, in its new position, start rubbing against the head of the humerus. Kim and colleagues¹⁴ found that, even when a knot is placed away from the humeral head, migration and repeated contact with the head are possible. Park and colleagues²⁸ found that a significant number of knotted SLAP repairs required arthroscopic knot removal for relief of knot-induced pain and clicking.

Knotless constructs have several theoretical advantages over knotted constructs. Compared with a knotted technique, a knotless technique appears to provide more predictable strength, as variability in knot tying is eliminated (unpublished data). A knotless repair also has a lower profile,8 which should lead to less contact with the humeral head.¹⁹ Last, a knotless repair is more efficient—it takes less time to perform. In our study, operative time was reduced by a mean of 5.3 minutes per anchor for anterior labral repair. Assuming a mean of 3 anchors, this reduction equates to 16 minutes per case. Therefore, a surgeon who performs 25 labral repairs a year can save 6.7 hours a year. Reduced operative time benefits the patient (ie, lower risk of infection and other complications²⁹), the surgeon, and the healthcare system (ie, cost savings). Macario³⁰ found that operating room costs averaged $62 per minute (range, $22-$133 per minute). Therefore, saving 16 minutes per case could lead to saving $992 per case. In summary, a knotless technique appears to be clinically and financially advantageous as long as its results are the same as or better than those of a knotted technique.

A few other studies have compared knotted and knotless techniques. In a cadaveric study, Slabaugh and colleagues²⁰ found no difference in labral height between traditional and knotless suture anchors. Leedle and Miller¹⁷ found that knotless constructs are biomechanically stronger than knotted constructs in anterior labral repair. In a level 3 clinical study, Yang and colleagues²¹ compared a conventional vertical knot with a knotless horizontal mattress suture in 41 patients who underwent SLAP repair. Functional outcome was no different between the 2 groups, but postoperative range of motion was improved in the knotless group. Ng and Kumar³¹ compared 45 patients who had knotted Bankart repair with 42 patients who had knotless Bankart repair and found no difference in functional outcome or rate of recurrent dislocation. Similarly, Kocaoglu and colleagues²² found no difference in recurrence rate between 18 patients who underwent a knotted technique for arthroscopic Bankart repair and 20 patients who underwent a knotless technique. Our findings corroborate the findings of these studies and further support the idea that there is no difference between knotted and knotless constructs with respect to PROMs.

Study Limitations

The major strength of this study was its large cohort and large population of surgeons. However, there were several study limitations. First, we could not detail specific repair techniques, such as simple or horizontal mattress orientation, and rehabilitation protocols and other variables are likely as well. Second, the repair technique was not randomized, and therefore there may have been a selection bias based on tissue quality. Although we cannot prove no bias, we think it was unlikely given that the groups were similar in age. Third, our data did not include information on range of motion or recurrent instability. Our goal was simply to evaluate PROMs among multiple surgeons using the 2 techniques. Fourth, there was substantial follow-up loss, which introduced potential selection bias. Last, there may have been conditions under which a hybrid technique with inferior knot tying, combined with a hybrid knotless construct, could have proved advantageous.

Conclusion

Our data showed that the advantages of knotless repair are not compromised in clinical situations. Although the data showed no significant difference in clinical outcomes, knotless repairs may provide surgeons with shorter surgeries, simpler constructs, less potential for chondral damage, and more consistent suture tensioning. Additional studies may further confirm these results.

Take-Home Points

• PRO data collection can provide feedback for improvements in patient care and physician performance.
• Many options exist for orthopedic physicians to establish clinical data registries.
• Registry systems can help improve patient follow-up with system monitoring and patient reminders.
• Clinical registries can offer many advantages to observational research.
• With registry use becoming more prevalent, work needs to be done to establish standards for validity and reliability.

In a 2012 review of database tools, Lubowitz and Smith¹ examined Internet-based applications that arthroscopic surgeons could use to record and monitor patient-reported outcome (PRO) data and potential adverse effects. In this article, we update orthopedic surgeons on the registries and monitoring software mentioned in that earlier publication and in other publications that have since become available.

Most orthopedic surgery candidates are seeking pain relief and improved function. Many patients expect their pain to be completely relieved by surgical intervention and their function to return to what it was before they became stricken.^2,3 Therefore, PRO measures (PROMs) are now standard in post-orthopedic surgery outcome reporting.⁴ PROMs, which include any measurement that assesses a patient’s health, illness, or benefits from the perspective of the patient, are often administered as a questionnaire or survey.⁵ The collection of PROMs continues to increase and evolve, creating a need for data storage and analysis. Registries, large collections of patient information and outcomes, allow for evaluation of patient outcomes, monitoring of adverse effects, identification of procedure incidence, understanding of predictors of prognosis, generation of feedback for quality of care, monitoring of the safety of implantable devices, and the conducting of hypothesis-driven scientific research.^6-9

Orthopedic surgery has registries at regional, national, and international levels. Although the United States has fallen well behind other countries in establishing a national registry,⁹ it has made some recent progress. The United States now has several national registries, including the American Joint Replacement Registry (AJRR), Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR), the Kaiser Permanente National Total Joint Replacement Registry (TJRR), the Veterans Affairs (VA) and American College of Surgeons (ACS) National Surgical Quality Improvement Programs (NSQIPs), and the National Trauma Data Bank (NTDB).⁹ AJRR currently has 960 hospitals participating and is tracking 1,084,664 hip and knee replacements.¹⁰

These orthopedic registries, however, are limited in 2 ways. First, the majority are joint replacement registries. Second, though registries are established to determine patterns of care and predict patient outcomes, many are not set up to report care data back to healthcare providers.⁷ For procedures other than joint arthroplasty and for providers interested in tracking their patients’ PROs, systems are available for establishing clinical quality registries in orthopedics.

Registry Systems

CareSense

CareSense (Medtrak) is an Internet-based care management and data collection system designed for patient engagement, which results in fewer missed appointments, increased patient adherence, enhanced patient education, and improved patient satisfaction.¹¹ CareSense features email/text reminders for data entry, custom and standard reports, import and export of electronic medical record (EMR) information, and tools for running research studies.¹² CareSense emphasizes care navigation by helping hospitals educate and guide patients through their care by sending exercise videos to patients for home rehabilitation, transferring messages from post-acute care facilities to surgeons and caregivers, and alerting the care team to any potential readmission symptoms.^11,13 CareSense is also a Centers for Medicare & Medicaid Services (CMS) approved qualified clinical data registry (QCDR). QCDRs collect data for Merit-Based Incentive Payment System (MIPS) clinicians and submit the data to CMS.¹²

KareOutcomes

KareOutcomes, a healthcare technology and support firm founded in 2009, advocates transparency and trust among providers and patients, and aims to optimize PROs.¹⁴ The KareOutcomes team incorporates patient follow-up personnel, administrators, engineers, physicians, software developers, and technicians. The KareOutcomes software, which is backed by a 6-month guarantee, includes system design and implementation, data collection and entry, methods of submitting data to statewide or nationwide registries and sending standardized and customized surveys, and accessible and meaningful data presentation. KareOutcomes allows patient follow-up through automated reminders by telephone, SMS text message, and email. Patients can respond to surveys or questionnaires whichever way is most convenient—by telephone, Internet, SMS text message, or on paper, either in the office or by mail.

Oberd

Oberd (Universal Research Solutions) offers a comprehensive package of solutions for collecting optimal PRO data. The package has several modules: outcomes, education, registry, operative notes, data import and export, and data reporting.¹⁵ Oberd Outcomes allows convenient and engaging data collection. For example, users can send both standardized and customized forms. Oberd Education allows patients to receive information in an interactive, narrated format that is specific to their physician’s techniques and practices. Oberd Registry allows users to input multiple datasets into a registry, compare data, and generate reports with visuals. Like CareSense, Oberd is a CMS-approved QCDR. Oberd’s MIPS Dashboard helps providers collect and report patients’ reported outcomes, and use that information to modify and improve their practice.

Ortech

Ortech is a web-based data registry system that allows physicians and administrators to mine the data they own, track key metrics in their data, and improve reporting.¹⁶ Users can collect PROMs, use them to measure and analyze patient progress, and add to their collection of information that helps support their evidence-based decision making. They can capture intraoperative and implant data through barcode scanning, which then registers the data in an implant product code library that allows quick identification of patients with a specific implant in the event of a product recall. Ortech also allows automatic generation of customized operative reports on data entered from the operating room and populated into the EMR. Ortech offers 2 versions of its data collection platform, phiDB and phiDB Lite. The phiDB Lite version is for smaller practices and focuses mainly on PROMs but lacks many of the other features that phiDB offers, such as operating room modules, automated operative reports, barcode scanning, and unlimited data reporting.

Socrates

Socrates (Standardised Orthopaedic Clinical Research and Treatment Evaluation Software; Ortholink) is dedicated orthopedic software that facilitates following patient outcomes and conducting high-quality research.¹⁷ Socrates is fully customizable to fit each user’s needs. It allows for tracking of outcome scores, intraoperative details, nonoperative procedures, clinical examinations, therapies, and adverse effects. Users can also create reports from this information, which is inputted to Socrates and can be exported into EMR. Socrates data are stored on the user’s server, on site; the software generates patient summaries, collective summaries, and follow-up reports through its built-in descriptive statistics module. Raw data can be extracted for statistical analysis. Socrates can catalogue images, radiographs, documents, and videos.

Surgical Outcomes System

Surgical Outcomes System (SOS; Arthrex) is a cloud-based orthopedic and sports medicine global registry that focuses on monitoring and evaluating the outcomes of various orthopedic and sports medicine surgical procedures, as well as nonoperative interventions, to contribute to evidence-based protocols for patient treatment.¹⁸ SOS can be fully customized with desired PROMs for arthroplasty and for surgical procedures for extremity joints and even the spine. SOS includes real-time reporting on PROs for individual patients, summary PROMs for all of the physician’s patients who are receiving the same treatment, and comparisons with all registry patients (from global de-identified registry data) who had the same treatment or surgery. This real-time analysis provides immediate patient and physician feedback on treatments and products used. A patient portal for education on surgical procedures is also available. SOS is approved for use in 21 countries and is a benefit included with Arthroscopy Association of North America (AANA) membership. SOS is listed on the National Quality Registry Network (NQRN) website and, as a specialized registry as defined by CMS, can accept data generated by EMR technology.

Discussion

Delaunay¹⁹ indicated that successful registry management depends on several factors, including “use of a single identifier for each patient to ensure full traceability of all procedures related to a given implant; a long-term funding source; a contemporary, rapid, Internet-based data collection method; and the collection of exhaustive data, at least for innovative implants.” The registry systems reviewed in this article are Internet based and allow healthcare providers to monitor the clinical outcomes of their patients in the hope of improving clinical decision-making and overall patient care. From the provider perspective, many registry systems allow for integration of outcome data reporting into EMRs, including generation of operative reports. In turn, registries can improve documentation efficiency, as it was estimated that a US physician without a registry spends more than 15 hours a week reporting quality measures,20 or almost 800 hours and $15 billion each year.^20,21 It remains to be seen whether registry systems will optimize the documentation process, but there is potential improvement in time and cost-efficiency with registry use.

Although the factors involved in management are important, clinical data registries must have systems in place to help ensure patient adherence and minimize selection bias, as adherence is crucial in data accuracy.³ What helps with adherence is the ability to send automated email or SMS text message reminders to patients. According to a review, email reminders increased the completion of PROM datasets by 26%.²² When the new national quality register (NQR) HAKIR (Handkirurgiskt kvalitetsregister) was established in Sweden, it was found that when only 1 type of reminder was used (SMS text message, in this case), only about 30% of participants completed their questionnaires.²³ However, after the system was changed to send both SMS text message and email reminders, the response rate increased from 50% to 60%. Using 2 types of automated reminders might minimize lost data more effectively than 1 type alone.

Another benefit of outcome monitoring through a registry is potential reduction of interviewer- related errors. Interviewer bias can occur in many different ways. Interviewers might not follow the same instructions or administer questionnaires or surveys the same way for different patients,²⁴ the interviewer’s presence might cause the patient to alter responses based on social norms,²⁵ and the patient might report better outcomes in the presence of a physician or interviewer.^26,27 Given that clinical registries allow electronic capture of self-administered surveys, interviewer bias is reduced because all patients receive a standardized set of questions and instructions. In addition, electronic questionnaires and surveys prompt users to add or fix missed or incorrectly completed items, further reducing potential data inaccuracies.

Healthcare costs continue to rise in the United States. In 2015, the total cost of healthcare expenditure in the United States was $3.2 trillion, or almost 18% of the US gross domestic product.²⁸ In addition, in the first half of 2016, an estimated 16.2% of people under age 65 years were in families that were struggling to pay medical bills.^29,30 Healthcare reform provides a financial incentive to healthcare providers to collaborate to reduce unnecessary costs and procedures and improve the quality of healthcare.³¹ Porter and Teisberg³² defined value as health outcomes achieved per dollar spent. Registry monitoring of PROMs, which are the numerator in this critical value formula, allows providers to track patient outcomes over time to determine which interventions produce the best outcomes.²² Therefore, clinical registries play an important role in improving health outcomes and reducing the cost of healthcare.⁷

Since the Swedish Knee Arthroplasty Register (SKAR) was established 40 years ago, NQRs have been commonplace in Scandinavian countries, Australia, and the United Kingdom.²³ Between 2001 and 2014, the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) documented a decline in the financial burden of hip and knee arthroplasty revision in Australia—in comparison with the United States, which did not have a full national registry at the time and showed a revision rate increase.²⁴ The economic benefit of reducing hip and knee arthroplasty revisions in Australia during that period was an estimated $65 million to $143 million.²⁴ Besides having financial benefits, national registries allow early identification of flawed implantation products and methods, leading to a further reduction in the burden associated with recall and future use of such defective implants—including patient harm.

In addition to monitoring existing techniques and devices, registries can also follow new techniques and, compared with publication in clinical journals, more expeditiously provide clinical data for outcome expectations and treatment methods. This timeliness is particularly valuable given that publication of clinical trials with the usual mandatory 2-year follow-up can take 4 years or longer.^33,34 For instance, in the expanding field of hip arthroscopy, data from registries in both Sweden and Denmark are being analyzed.^35,36 These data are important in new fields such as hip arthroscopy, in which clinical indications and treatment techniques may vary considerably between locations.³⁵ In 2012, the Danish Hip Arthroscopy Registry (DHAR) was started as a web-based prospective registry.³⁶ Between 2012 and December 2014, DHAR added 2000 procedures, which included all hip arthroscopy procedures performed at 11 centers in Denmark.³⁶ DHAR tracks PROM, surgical procedure, operative, and radiologic data.

Increased use of clinical registries has led to use of their data in clinical research. Registry-based randomized controlled trials (RCTs) are lower in cost than other types of research, allow for rapid enrollment of patients, offer larger population sizes and multi-institutional sampling, and can provide a more diverse patient population.^19,37 Although nonregistry RCTs remain the gold standard of clinical research, registry RCTs have several advantages given the abilities and structure of registries. Because of resources and cost, nonregistry RCTs are usually limited in the number of examined exposures and typically focus on only 2.6 Registry RCTs, on the other hand, can monitor multiple exposures, typically at minimal cost difference.⁶ Another disadvantage of nonregistry RCTs is that they are often performed at institutions providing care that might not be indicative of the quality most patients expect, as these institutions might be selected for a specific clinician or specialty service.

Registry RCTs also have their limitations with respect to clinical research. A major one is their lack of validity standards or accepted benchmarks for accuracy, adherence rates, registry completeness, and data collection.^37,38 In addition, lack of standardization across national and international registries could produce conflicting data. Another limitation is that data in most registries are not subjected to any third-party checks or independent auditing.^9,39 Furthermore, evaluating the impact of registries is difficult because it is difficult to find comparable outcome data on nonregistry patients.⁴⁰ A final limitation involves the ethics of including registry data in RCTs. Although data are often added to a registry without patient consent, should the same data be used for research without patient consent? Should patients be able to disallow use of their data for research, or require a notification each time their data are used? These issues must be addressed.

Review Limitations 

One limitation of this review of clinical Internet-based outcome systems is that it might not have identified comparable systems. In addition, specific costs associated with each system were not addressed, as they depend on PROM licensing fees, total institutional access, other proprietary costs, and other variables. Another limitation, in terms of creating a national or international registry, continues to be Internet access. The Pew Research Center estimated that 84% of US adults used the Internet in 2015.⁴¹ Although 84% represents most of the adult population, the other 16% typically is over age 65 years, where only 58% of adults reported using the Internet, or come from lower income households, where access was <75%. For registries in European countries and North America, where Internet usage typically is >70%, this is not a significant problem. However, worldwide, only 47% of the population used the Internet in 2016.⁴² Internet usage by Asian and Arab states citizens was 41.6% and 41.9%, respectively, and usage by African citizens was only 25.1%. As a significant benefit of registry use is that researchers can obtain larger sample sizes, it is a problem that some populations—elderly people, people of lower socioeconomic standing, people living where the Internet is unavailable—might be underrepresented in registry data.

As mentioned, patient adherence is an ongoing issue for clinical registries. As adherence tends to decrease as more time passes after a patient’s treatment date, it is important to account for and encourage continued patient participation with outcome monitoring. Missing data lessen the validity and accuracy of a registry, increasing the likelihood that certain groups will be underrepresented. Although registry systems can reduce the cost of following PROMs, doing so requires monitoring and following up on issues of patient adherence. In other words, many clinicians will need the help of a research assistant. Makhni and colleagues²¹ found that adding a research assistant for this task increased survey adherence from 65% to 94% before surgery, from 65% to 72% 6 months after surgery, and from 38% to 56% 12 months after surgery.

Even though studies continue to use clinical data from registries, there is not much research on the impact of these registries on improvement in healthcare. Again, many factors are involved: lack of standardized benchmarks for accuracy and adherence, lack of an accepted method of data auditing and validation, and difficulty evaluating the impact of registries owing to the difficulty obtaining comparable data on nonregistry patients. Registries must adopt accepted forms of standardization in order to allow better comparisons of registries, because comparing data across registries can be useful in determining the strengths and weaknesses of different registries.^27,43 As registries support decision making at clinical, institutional, and governmental levels, it is vital that their clinical data be accurate and reliable.³⁸

Conclusion

Rising healthcare costs, and government and third-party pressures are making patient outcomes collection a standard of care. Going forward, orthopedic surgeons must be proactive, and Internet -based registries provide technological advances that facilitate the process.

Take-Home Points

• PRO data collection can provide feedback for improvements in patient care and physician performance.
• Many options exist for orthopedic physicians to establish clinical data registries.
• Registry systems can help improve patient follow-up with system monitoring and patient reminders.
• Clinical registries can offer many advantages to observational research.
• With registry use becoming more prevalent, work needs to be done to establish standards for validity and reliability.

In a 2012 review of database tools, Lubowitz and Smith¹ examined Internet-based applications that arthroscopic surgeons could use to record and monitor patient-reported outcome (PRO) data and potential adverse effects. In this article, we update orthopedic surgeons on the registries and monitoring software mentioned in that earlier publication and in other publications that have since become available.

Most orthopedic surgery candidates are seeking pain relief and improved function. Many patients expect their pain to be completely relieved by surgical intervention and their function to return to what it was before they became stricken.^2,3 Therefore, PRO measures (PROMs) are now standard in post-orthopedic surgery outcome reporting.⁴ PROMs, which include any measurement that assesses a patient’s health, illness, or benefits from the perspective of the patient, are often administered as a questionnaire or survey.⁵ The collection of PROMs continues to increase and evolve, creating a need for data storage and analysis. Registries, large collections of patient information and outcomes, allow for evaluation of patient outcomes, monitoring of adverse effects, identification of procedure incidence, understanding of predictors of prognosis, generation of feedback for quality of care, monitoring of the safety of implantable devices, and the conducting of hypothesis-driven scientific research.^6-9

Orthopedic surgery has registries at regional, national, and international levels. Although the United States has fallen well behind other countries in establishing a national registry,⁹ it has made some recent progress. The United States now has several national registries, including the American Joint Replacement Registry (AJRR), Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR), the Kaiser Permanente National Total Joint Replacement Registry (TJRR), the Veterans Affairs (VA) and American College of Surgeons (ACS) National Surgical Quality Improvement Programs (NSQIPs), and the National Trauma Data Bank (NTDB).⁹ AJRR currently has 960 hospitals participating and is tracking 1,084,664 hip and knee replacements.¹⁰

These orthopedic registries, however, are limited in 2 ways. First, the majority are joint replacement registries. Second, though registries are established to determine patterns of care and predict patient outcomes, many are not set up to report care data back to healthcare providers.⁷ For procedures other than joint arthroplasty and for providers interested in tracking their patients’ PROs, systems are available for establishing clinical quality registries in orthopedics.

Registry Systems

CareSense

CareSense (Medtrak) is an Internet-based care management and data collection system designed for patient engagement, which results in fewer missed appointments, increased patient adherence, enhanced patient education, and improved patient satisfaction.¹¹ CareSense features email/text reminders for data entry, custom and standard reports, import and export of electronic medical record (EMR) information, and tools for running research studies.¹² CareSense emphasizes care navigation by helping hospitals educate and guide patients through their care by sending exercise videos to patients for home rehabilitation, transferring messages from post-acute care facilities to surgeons and caregivers, and alerting the care team to any potential readmission symptoms.^11,13 CareSense is also a Centers for Medicare & Medicaid Services (CMS) approved qualified clinical data registry (QCDR). QCDRs collect data for Merit-Based Incentive Payment System (MIPS) clinicians and submit the data to CMS.¹²

KareOutcomes

KareOutcomes, a healthcare technology and support firm founded in 2009, advocates transparency and trust among providers and patients, and aims to optimize PROs.¹⁴ The KareOutcomes team incorporates patient follow-up personnel, administrators, engineers, physicians, software developers, and technicians. The KareOutcomes software, which is backed by a 6-month guarantee, includes system design and implementation, data collection and entry, methods of submitting data to statewide or nationwide registries and sending standardized and customized surveys, and accessible and meaningful data presentation. KareOutcomes allows patient follow-up through automated reminders by telephone, SMS text message, and email. Patients can respond to surveys or questionnaires whichever way is most convenient—by telephone, Internet, SMS text message, or on paper, either in the office or by mail.

Oberd

Oberd (Universal Research Solutions) offers a comprehensive package of solutions for collecting optimal PRO data. The package has several modules: outcomes, education, registry, operative notes, data import and export, and data reporting.¹⁵ Oberd Outcomes allows convenient and engaging data collection. For example, users can send both standardized and customized forms. Oberd Education allows patients to receive information in an interactive, narrated format that is specific to their physician’s techniques and practices. Oberd Registry allows users to input multiple datasets into a registry, compare data, and generate reports with visuals. Like CareSense, Oberd is a CMS-approved QCDR. Oberd’s MIPS Dashboard helps providers collect and report patients’ reported outcomes, and use that information to modify and improve their practice.

Ortech

Ortech is a web-based data registry system that allows physicians and administrators to mine the data they own, track key metrics in their data, and improve reporting.¹⁶ Users can collect PROMs, use them to measure and analyze patient progress, and add to their collection of information that helps support their evidence-based decision making. They can capture intraoperative and implant data through barcode scanning, which then registers the data in an implant product code library that allows quick identification of patients with a specific implant in the event of a product recall. Ortech also allows automatic generation of customized operative reports on data entered from the operating room and populated into the EMR. Ortech offers 2 versions of its data collection platform, phiDB and phiDB Lite. The phiDB Lite version is for smaller practices and focuses mainly on PROMs but lacks many of the other features that phiDB offers, such as operating room modules, automated operative reports, barcode scanning, and unlimited data reporting.

Socrates

Socrates (Standardised Orthopaedic Clinical Research and Treatment Evaluation Software; Ortholink) is dedicated orthopedic software that facilitates following patient outcomes and conducting high-quality research.¹⁷ Socrates is fully customizable to fit each user’s needs. It allows for tracking of outcome scores, intraoperative details, nonoperative procedures, clinical examinations, therapies, and adverse effects. Users can also create reports from this information, which is inputted to Socrates and can be exported into EMR. Socrates data are stored on the user’s server, on site; the software generates patient summaries, collective summaries, and follow-up reports through its built-in descriptive statistics module. Raw data can be extracted for statistical analysis. Socrates can catalogue images, radiographs, documents, and videos.

Surgical Outcomes System

Surgical Outcomes System (SOS; Arthrex) is a cloud-based orthopedic and sports medicine global registry that focuses on monitoring and evaluating the outcomes of various orthopedic and sports medicine surgical procedures, as well as nonoperative interventions, to contribute to evidence-based protocols for patient treatment.¹⁸ SOS can be fully customized with desired PROMs for arthroplasty and for surgical procedures for extremity joints and even the spine. SOS includes real-time reporting on PROs for individual patients, summary PROMs for all of the physician’s patients who are receiving the same treatment, and comparisons with all registry patients (from global de-identified registry data) who had the same treatment or surgery. This real-time analysis provides immediate patient and physician feedback on treatments and products used. A patient portal for education on surgical procedures is also available. SOS is approved for use in 21 countries and is a benefit included with Arthroscopy Association of North America (AANA) membership. SOS is listed on the National Quality Registry Network (NQRN) website and, as a specialized registry as defined by CMS, can accept data generated by EMR technology.

Discussion

Delaunay¹⁹ indicated that successful registry management depends on several factors, including “use of a single identifier for each patient to ensure full traceability of all procedures related to a given implant; a long-term funding source; a contemporary, rapid, Internet-based data collection method; and the collection of exhaustive data, at least for innovative implants.” The registry systems reviewed in this article are Internet based and allow healthcare providers to monitor the clinical outcomes of their patients in the hope of improving clinical decision-making and overall patient care. From the provider perspective, many registry systems allow for integration of outcome data reporting into EMRs, including generation of operative reports. In turn, registries can improve documentation efficiency, as it was estimated that a US physician without a registry spends more than 15 hours a week reporting quality measures,20 or almost 800 hours and $15 billion each year.^20,21 It remains to be seen whether registry systems will optimize the documentation process, but there is potential improvement in time and cost-efficiency with registry use.

Although the factors involved in management are important, clinical data registries must have systems in place to help ensure patient adherence and minimize selection bias, as adherence is crucial in data accuracy.³ What helps with adherence is the ability to send automated email or SMS text message reminders to patients. According to a review, email reminders increased the completion of PROM datasets by 26%.²² When the new national quality register (NQR) HAKIR (Handkirurgiskt kvalitetsregister) was established in Sweden, it was found that when only 1 type of reminder was used (SMS text message, in this case), only about 30% of participants completed their questionnaires.²³ However, after the system was changed to send both SMS text message and email reminders, the response rate increased from 50% to 60%. Using 2 types of automated reminders might minimize lost data more effectively than 1 type alone.

Another benefit of outcome monitoring through a registry is potential reduction of interviewer- related errors. Interviewer bias can occur in many different ways. Interviewers might not follow the same instructions or administer questionnaires or surveys the same way for different patients,²⁴ the interviewer’s presence might cause the patient to alter responses based on social norms,²⁵ and the patient might report better outcomes in the presence of a physician or interviewer.^26,27 Given that clinical registries allow electronic capture of self-administered surveys, interviewer bias is reduced because all patients receive a standardized set of questions and instructions. In addition, electronic questionnaires and surveys prompt users to add or fix missed or incorrectly completed items, further reducing potential data inaccuracies.

Healthcare costs continue to rise in the United States. In 2015, the total cost of healthcare expenditure in the United States was $3.2 trillion, or almost 18% of the US gross domestic product.²⁸ In addition, in the first half of 2016, an estimated 16.2% of people under age 65 years were in families that were struggling to pay medical bills.^29,30 Healthcare reform provides a financial incentive to healthcare providers to collaborate to reduce unnecessary costs and procedures and improve the quality of healthcare.³¹ Porter and Teisberg³² defined value as health outcomes achieved per dollar spent. Registry monitoring of PROMs, which are the numerator in this critical value formula, allows providers to track patient outcomes over time to determine which interventions produce the best outcomes.²² Therefore, clinical registries play an important role in improving health outcomes and reducing the cost of healthcare.⁷

Since the Swedish Knee Arthroplasty Register (SKAR) was established 40 years ago, NQRs have been commonplace in Scandinavian countries, Australia, and the United Kingdom.²³ Between 2001 and 2014, the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) documented a decline in the financial burden of hip and knee arthroplasty revision in Australia—in comparison with the United States, which did not have a full national registry at the time and showed a revision rate increase.²⁴ The economic benefit of reducing hip and knee arthroplasty revisions in Australia during that period was an estimated $65 million to $143 million.²⁴ Besides having financial benefits, national registries allow early identification of flawed implantation products and methods, leading to a further reduction in the burden associated with recall and future use of such defective implants—including patient harm.

In addition to monitoring existing techniques and devices, registries can also follow new techniques and, compared with publication in clinical journals, more expeditiously provide clinical data for outcome expectations and treatment methods. This timeliness is particularly valuable given that publication of clinical trials with the usual mandatory 2-year follow-up can take 4 years or longer.^33,34 For instance, in the expanding field of hip arthroscopy, data from registries in both Sweden and Denmark are being analyzed.^35,36 These data are important in new fields such as hip arthroscopy, in which clinical indications and treatment techniques may vary considerably between locations.³⁵ In 2012, the Danish Hip Arthroscopy Registry (DHAR) was started as a web-based prospective registry.³⁶ Between 2012 and December 2014, DHAR added 2000 procedures, which included all hip arthroscopy procedures performed at 11 centers in Denmark.³⁶ DHAR tracks PROM, surgical procedure, operative, and radiologic data.

Increased use of clinical registries has led to use of their data in clinical research. Registry-based randomized controlled trials (RCTs) are lower in cost than other types of research, allow for rapid enrollment of patients, offer larger population sizes and multi-institutional sampling, and can provide a more diverse patient population.^19,37 Although nonregistry RCTs remain the gold standard of clinical research, registry RCTs have several advantages given the abilities and structure of registries. Because of resources and cost, nonregistry RCTs are usually limited in the number of examined exposures and typically focus on only 2.6 Registry RCTs, on the other hand, can monitor multiple exposures, typically at minimal cost difference.⁶ Another disadvantage of nonregistry RCTs is that they are often performed at institutions providing care that might not be indicative of the quality most patients expect, as these institutions might be selected for a specific clinician or specialty service.

Registry RCTs also have their limitations with respect to clinical research. A major one is their lack of validity standards or accepted benchmarks for accuracy, adherence rates, registry completeness, and data collection.^37,38 In addition, lack of standardization across national and international registries could produce conflicting data. Another limitation is that data in most registries are not subjected to any third-party checks or independent auditing.^9,39 Furthermore, evaluating the impact of registries is difficult because it is difficult to find comparable outcome data on nonregistry patients.⁴⁰ A final limitation involves the ethics of including registry data in RCTs. Although data are often added to a registry without patient consent, should the same data be used for research without patient consent? Should patients be able to disallow use of their data for research, or require a notification each time their data are used? These issues must be addressed.

Review Limitations 

One limitation of this review of clinical Internet-based outcome systems is that it might not have identified comparable systems. In addition, specific costs associated with each system were not addressed, as they depend on PROM licensing fees, total institutional access, other proprietary costs, and other variables. Another limitation, in terms of creating a national or international registry, continues to be Internet access. The Pew Research Center estimated that 84% of US adults used the Internet in 2015.⁴¹ Although 84% represents most of the adult population, the other 16% typically is over age 65 years, where only 58% of adults reported using the Internet, or come from lower income households, where access was <75%. For registries in European countries and North America, where Internet usage typically is >70%, this is not a significant problem. However, worldwide, only 47% of the population used the Internet in 2016.⁴² Internet usage by Asian and Arab states citizens was 41.6% and 41.9%, respectively, and usage by African citizens was only 25.1%. As a significant benefit of registry use is that researchers can obtain larger sample sizes, it is a problem that some populations—elderly people, people of lower socioeconomic standing, people living where the Internet is unavailable—might be underrepresented in registry data.

As mentioned, patient adherence is an ongoing issue for clinical registries. As adherence tends to decrease as more time passes after a patient’s treatment date, it is important to account for and encourage continued patient participation with outcome monitoring. Missing data lessen the validity and accuracy of a registry, increasing the likelihood that certain groups will be underrepresented. Although registry systems can reduce the cost of following PROMs, doing so requires monitoring and following up on issues of patient adherence. In other words, many clinicians will need the help of a research assistant. Makhni and colleagues²¹ found that adding a research assistant for this task increased survey adherence from 65% to 94% before surgery, from 65% to 72% 6 months after surgery, and from 38% to 56% 12 months after surgery.

Even though studies continue to use clinical data from registries, there is not much research on the impact of these registries on improvement in healthcare. Again, many factors are involved: lack of standardized benchmarks for accuracy and adherence, lack of an accepted method of data auditing and validation, and difficulty evaluating the impact of registries owing to the difficulty obtaining comparable data on nonregistry patients. Registries must adopt accepted forms of standardization in order to allow better comparisons of registries, because comparing data across registries can be useful in determining the strengths and weaknesses of different registries.^27,43 As registries support decision making at clinical, institutional, and governmental levels, it is vital that their clinical data be accurate and reliable.³⁸

Conclusion

Rising healthcare costs, and government and third-party pressures are making patient outcomes collection a standard of care. Going forward, orthopedic surgeons must be proactive, and Internet -based registries provide technological advances that facilitate the process.

Take-Home Points

• PRO data collection can provide feedback for improvements in patient care and physician performance.
• Many options exist for orthopedic physicians to establish clinical data registries.
• Registry systems can help improve patient follow-up with system monitoring and patient reminders.
• Clinical registries can offer many advantages to observational research.
• With registry use becoming more prevalent, work needs to be done to establish standards for validity and reliability.

In a 2012 review of database tools, Lubowitz and Smith¹ examined Internet-based applications that arthroscopic surgeons could use to record and monitor patient-reported outcome (PRO) data and potential adverse effects. In this article, we update orthopedic surgeons on the registries and monitoring software mentioned in that earlier publication and in other publications that have since become available.

Most orthopedic surgery candidates are seeking pain relief and improved function. Many patients expect their pain to be completely relieved by surgical intervention and their function to return to what it was before they became stricken.^2,3 Therefore, PRO measures (PROMs) are now standard in post-orthopedic surgery outcome reporting.⁴ PROMs, which include any measurement that assesses a patient’s health, illness, or benefits from the perspective of the patient, are often administered as a questionnaire or survey.⁵ The collection of PROMs continues to increase and evolve, creating a need for data storage and analysis. Registries, large collections of patient information and outcomes, allow for evaluation of patient outcomes, monitoring of adverse effects, identification of procedure incidence, understanding of predictors of prognosis, generation of feedback for quality of care, monitoring of the safety of implantable devices, and the conducting of hypothesis-driven scientific research.^6-9

Orthopedic surgery has registries at regional, national, and international levels. Although the United States has fallen well behind other countries in establishing a national registry,⁹ it has made some recent progress. The United States now has several national registries, including the American Joint Replacement Registry (AJRR), Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR), the Kaiser Permanente National Total Joint Replacement Registry (TJRR), the Veterans Affairs (VA) and American College of Surgeons (ACS) National Surgical Quality Improvement Programs (NSQIPs), and the National Trauma Data Bank (NTDB).⁹ AJRR currently has 960 hospitals participating and is tracking 1,084,664 hip and knee replacements.¹⁰

These orthopedic registries, however, are limited in 2 ways. First, the majority are joint replacement registries. Second, though registries are established to determine patterns of care and predict patient outcomes, many are not set up to report care data back to healthcare providers.⁷ For procedures other than joint arthroplasty and for providers interested in tracking their patients’ PROs, systems are available for establishing clinical quality registries in orthopedics.

Registry Systems

CareSense

CareSense (Medtrak) is an Internet-based care management and data collection system designed for patient engagement, which results in fewer missed appointments, increased patient adherence, enhanced patient education, and improved patient satisfaction.¹¹ CareSense features email/text reminders for data entry, custom and standard reports, import and export of electronic medical record (EMR) information, and tools for running research studies.¹² CareSense emphasizes care navigation by helping hospitals educate and guide patients through their care by sending exercise videos to patients for home rehabilitation, transferring messages from post-acute care facilities to surgeons and caregivers, and alerting the care team to any potential readmission symptoms.^11,13 CareSense is also a Centers for Medicare & Medicaid Services (CMS) approved qualified clinical data registry (QCDR). QCDRs collect data for Merit-Based Incentive Payment System (MIPS) clinicians and submit the data to CMS.¹²

KareOutcomes

KareOutcomes, a healthcare technology and support firm founded in 2009, advocates transparency and trust among providers and patients, and aims to optimize PROs.¹⁴ The KareOutcomes team incorporates patient follow-up personnel, administrators, engineers, physicians, software developers, and technicians. The KareOutcomes software, which is backed by a 6-month guarantee, includes system design and implementation, data collection and entry, methods of submitting data to statewide or nationwide registries and sending standardized and customized surveys, and accessible and meaningful data presentation. KareOutcomes allows patient follow-up through automated reminders by telephone, SMS text message, and email. Patients can respond to surveys or questionnaires whichever way is most convenient—by telephone, Internet, SMS text message, or on paper, either in the office or by mail.

Oberd

Oberd (Universal Research Solutions) offers a comprehensive package of solutions for collecting optimal PRO data. The package has several modules: outcomes, education, registry, operative notes, data import and export, and data reporting.¹⁵ Oberd Outcomes allows convenient and engaging data collection. For example, users can send both standardized and customized forms. Oberd Education allows patients to receive information in an interactive, narrated format that is specific to their physician’s techniques and practices. Oberd Registry allows users to input multiple datasets into a registry, compare data, and generate reports with visuals. Like CareSense, Oberd is a CMS-approved QCDR. Oberd’s MIPS Dashboard helps providers collect and report patients’ reported outcomes, and use that information to modify and improve their practice.

Ortech

Ortech is a web-based data registry system that allows physicians and administrators to mine the data they own, track key metrics in their data, and improve reporting.¹⁶ Users can collect PROMs, use them to measure and analyze patient progress, and add to their collection of information that helps support their evidence-based decision making. They can capture intraoperative and implant data through barcode scanning, which then registers the data in an implant product code library that allows quick identification of patients with a specific implant in the event of a product recall. Ortech also allows automatic generation of customized operative reports on data entered from the operating room and populated into the EMR. Ortech offers 2 versions of its data collection platform, phiDB and phiDB Lite. The phiDB Lite version is for smaller practices and focuses mainly on PROMs but lacks many of the other features that phiDB offers, such as operating room modules, automated operative reports, barcode scanning, and unlimited data reporting.

Socrates

Socrates (Standardised Orthopaedic Clinical Research and Treatment Evaluation Software; Ortholink) is dedicated orthopedic software that facilitates following patient outcomes and conducting high-quality research.¹⁷ Socrates is fully customizable to fit each user’s needs. It allows for tracking of outcome scores, intraoperative details, nonoperative procedures, clinical examinations, therapies, and adverse effects. Users can also create reports from this information, which is inputted to Socrates and can be exported into EMR. Socrates data are stored on the user’s server, on site; the software generates patient summaries, collective summaries, and follow-up reports through its built-in descriptive statistics module. Raw data can be extracted for statistical analysis. Socrates can catalogue images, radiographs, documents, and videos.

Surgical Outcomes System

Surgical Outcomes System (SOS; Arthrex) is a cloud-based orthopedic and sports medicine global registry that focuses on monitoring and evaluating the outcomes of various orthopedic and sports medicine surgical procedures, as well as nonoperative interventions, to contribute to evidence-based protocols for patient treatment.¹⁸ SOS can be fully customized with desired PROMs for arthroplasty and for surgical procedures for extremity joints and even the spine. SOS includes real-time reporting on PROs for individual patients, summary PROMs for all of the physician’s patients who are receiving the same treatment, and comparisons with all registry patients (from global de-identified registry data) who had the same treatment or surgery. This real-time analysis provides immediate patient and physician feedback on treatments and products used. A patient portal for education on surgical procedures is also available. SOS is approved for use in 21 countries and is a benefit included with Arthroscopy Association of North America (AANA) membership. SOS is listed on the National Quality Registry Network (NQRN) website and, as a specialized registry as defined by CMS, can accept data generated by EMR technology.

Discussion

Delaunay¹⁹ indicated that successful registry management depends on several factors, including “use of a single identifier for each patient to ensure full traceability of all procedures related to a given implant; a long-term funding source; a contemporary, rapid, Internet-based data collection method; and the collection of exhaustive data, at least for innovative implants.” The registry systems reviewed in this article are Internet based and allow healthcare providers to monitor the clinical outcomes of their patients in the hope of improving clinical decision-making and overall patient care. From the provider perspective, many registry systems allow for integration of outcome data reporting into EMRs, including generation of operative reports. In turn, registries can improve documentation efficiency, as it was estimated that a US physician without a registry spends more than 15 hours a week reporting quality measures,20 or almost 800 hours and $15 billion each year.^20,21 It remains to be seen whether registry systems will optimize the documentation process, but there is potential improvement in time and cost-efficiency with registry use.

Although the factors involved in management are important, clinical data registries must have systems in place to help ensure patient adherence and minimize selection bias, as adherence is crucial in data accuracy.³ What helps with adherence is the ability to send automated email or SMS text message reminders to patients. According to a review, email reminders increased the completion of PROM datasets by 26%.²² When the new national quality register (NQR) HAKIR (Handkirurgiskt kvalitetsregister) was established in Sweden, it was found that when only 1 type of reminder was used (SMS text message, in this case), only about 30% of participants completed their questionnaires.²³ However, after the system was changed to send both SMS text message and email reminders, the response rate increased from 50% to 60%. Using 2 types of automated reminders might minimize lost data more effectively than 1 type alone.

Another benefit of outcome monitoring through a registry is potential reduction of interviewer- related errors. Interviewer bias can occur in many different ways. Interviewers might not follow the same instructions or administer questionnaires or surveys the same way for different patients,²⁴ the interviewer’s presence might cause the patient to alter responses based on social norms,²⁵ and the patient might report better outcomes in the presence of a physician or interviewer.^26,27 Given that clinical registries allow electronic capture of self-administered surveys, interviewer bias is reduced because all patients receive a standardized set of questions and instructions. In addition, electronic questionnaires and surveys prompt users to add or fix missed or incorrectly completed items, further reducing potential data inaccuracies.

Healthcare costs continue to rise in the United States. In 2015, the total cost of healthcare expenditure in the United States was $3.2 trillion, or almost 18% of the US gross domestic product.²⁸ In addition, in the first half of 2016, an estimated 16.2% of people under age 65 years were in families that were struggling to pay medical bills.^29,30 Healthcare reform provides a financial incentive to healthcare providers to collaborate to reduce unnecessary costs and procedures and improve the quality of healthcare.³¹ Porter and Teisberg³² defined value as health outcomes achieved per dollar spent. Registry monitoring of PROMs, which are the numerator in this critical value formula, allows providers to track patient outcomes over time to determine which interventions produce the best outcomes.²² Therefore, clinical registries play an important role in improving health outcomes and reducing the cost of healthcare.⁷

Since the Swedish Knee Arthroplasty Register (SKAR) was established 40 years ago, NQRs have been commonplace in Scandinavian countries, Australia, and the United Kingdom.²³ Between 2001 and 2014, the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) documented a decline in the financial burden of hip and knee arthroplasty revision in Australia—in comparison with the United States, which did not have a full national registry at the time and showed a revision rate increase.²⁴ The economic benefit of reducing hip and knee arthroplasty revisions in Australia during that period was an estimated $65 million to $143 million.²⁴ Besides having financial benefits, national registries allow early identification of flawed implantation products and methods, leading to a further reduction in the burden associated with recall and future use of such defective implants—including patient harm.

In addition to monitoring existing techniques and devices, registries can also follow new techniques and, compared with publication in clinical journals, more expeditiously provide clinical data for outcome expectations and treatment methods. This timeliness is particularly valuable given that publication of clinical trials with the usual mandatory 2-year follow-up can take 4 years or longer.^33,34 For instance, in the expanding field of hip arthroscopy, data from registries in both Sweden and Denmark are being analyzed.^35,36 These data are important in new fields such as hip arthroscopy, in which clinical indications and treatment techniques may vary considerably between locations.³⁵ In 2012, the Danish Hip Arthroscopy Registry (DHAR) was started as a web-based prospective registry.³⁶ Between 2012 and December 2014, DHAR added 2000 procedures, which included all hip arthroscopy procedures performed at 11 centers in Denmark.³⁶ DHAR tracks PROM, surgical procedure, operative, and radiologic data.

Increased use of clinical registries has led to use of their data in clinical research. Registry-based randomized controlled trials (RCTs) are lower in cost than other types of research, allow for rapid enrollment of patients, offer larger population sizes and multi-institutional sampling, and can provide a more diverse patient population.^19,37 Although nonregistry RCTs remain the gold standard of clinical research, registry RCTs have several advantages given the abilities and structure of registries. Because of resources and cost, nonregistry RCTs are usually limited in the number of examined exposures and typically focus on only 2.6 Registry RCTs, on the other hand, can monitor multiple exposures, typically at minimal cost difference.⁶ Another disadvantage of nonregistry RCTs is that they are often performed at institutions providing care that might not be indicative of the quality most patients expect, as these institutions might be selected for a specific clinician or specialty service.

Registry RCTs also have their limitations with respect to clinical research. A major one is their lack of validity standards or accepted benchmarks for accuracy, adherence rates, registry completeness, and data collection.^37,38 In addition, lack of standardization across national and international registries could produce conflicting data. Another limitation is that data in most registries are not subjected to any third-party checks or independent auditing.^9,39 Furthermore, evaluating the impact of registries is difficult because it is difficult to find comparable outcome data on nonregistry patients.⁴⁰ A final limitation involves the ethics of including registry data in RCTs. Although data are often added to a registry without patient consent, should the same data be used for research without patient consent? Should patients be able to disallow use of their data for research, or require a notification each time their data are used? These issues must be addressed.

Review Limitations 

One limitation of this review of clinical Internet-based outcome systems is that it might not have identified comparable systems. In addition, specific costs associated with each system were not addressed, as they depend on PROM licensing fees, total institutional access, other proprietary costs, and other variables. Another limitation, in terms of creating a national or international registry, continues to be Internet access. The Pew Research Center estimated that 84% of US adults used the Internet in 2015.⁴¹ Although 84% represents most of the adult population, the other 16% typically is over age 65 years, where only 58% of adults reported using the Internet, or come from lower income households, where access was <75%. For registries in European countries and North America, where Internet usage typically is >70%, this is not a significant problem. However, worldwide, only 47% of the population used the Internet in 2016.⁴² Internet usage by Asian and Arab states citizens was 41.6% and 41.9%, respectively, and usage by African citizens was only 25.1%. As a significant benefit of registry use is that researchers can obtain larger sample sizes, it is a problem that some populations—elderly people, people of lower socioeconomic standing, people living where the Internet is unavailable—might be underrepresented in registry data.

As mentioned, patient adherence is an ongoing issue for clinical registries. As adherence tends to decrease as more time passes after a patient’s treatment date, it is important to account for and encourage continued patient participation with outcome monitoring. Missing data lessen the validity and accuracy of a registry, increasing the likelihood that certain groups will be underrepresented. Although registry systems can reduce the cost of following PROMs, doing so requires monitoring and following up on issues of patient adherence. In other words, many clinicians will need the help of a research assistant. Makhni and colleagues²¹ found that adding a research assistant for this task increased survey adherence from 65% to 94% before surgery, from 65% to 72% 6 months after surgery, and from 38% to 56% 12 months after surgery.

Even though studies continue to use clinical data from registries, there is not much research on the impact of these registries on improvement in healthcare. Again, many factors are involved: lack of standardized benchmarks for accuracy and adherence, lack of an accepted method of data auditing and validation, and difficulty evaluating the impact of registries owing to the difficulty obtaining comparable data on nonregistry patients. Registries must adopt accepted forms of standardization in order to allow better comparisons of registries, because comparing data across registries can be useful in determining the strengths and weaknesses of different registries.^27,43 As registries support decision making at clinical, institutional, and governmental levels, it is vital that their clinical data be accurate and reliable.³⁸

Conclusion

Rising healthcare costs, and government and third-party pressures are making patient outcomes collection a standard of care. Going forward, orthopedic surgeons must be proactive, and Internet -based registries provide technological advances that facilitate the process.

Take-Home Points

• The SCR is a viable treatment option for massive, irreparable RCTs.
• Arm position and exact measurement between anchors will help ensure proper graft tensioning.
• Anterior and posterior tension and margin convergence are critical to stabilizing the graft.
• Acromial-humeral distance, ASES, and VAS scores are improved and maintained over long-term follow-up.
• The dermal allograft should be 3.0 mm or thicker.

Conventional treatments for irreparable massive rotator cuff tears (RCTs) have ranged from nonoperative care to débridement and biceps tenotomy,^1,2 partial cuff repair,^3,4 bridging patch grafts,⁵ tendon transfers,^6,7 and reverse total shoulder arthroplasty (RTSA).^8,9 Superior capsular reconstruction (SCR), originally described by Mihata and colleagues,¹⁰ has been developed as an alternative to these interventions. Dr. Hirahara modified the technique to use dermal allograft instead of fascia lata autograft.^10,11

Biomechanical analysis has confirmed the integral role of the superior capsule in shoulder function.^10,12-14 In the presence of a massive RCT, the humeral head migrates superiorly, causing significant pain and functional deficits, such as pseudoparalysis. It is theorized that reestablishing this important stabilizer—centering the humeral head in the glenoid and allowing the larger muscles to move the arm about a proper fulcrum—improves function and decreases pain.

Using ultrasonography (US), radiography, magnetic resonance imaging (MRI), clinical outcome scores, and a visual analog scale (VAS) for pain, we prospectively evaluated minimum 2-year clinical outcomes of performing SCR with dermal allograft for irreparable RCTs.

Methods

Except where noted otherwise, all products mentioned in this section were made by Arthrex.

Surgical Technique

The surgical technique used here was described by Hirahara and Adams.¹¹ ArthroFlex dermal allograft was attached to the greater tuberosity and the glenoid, creating a superior restraint that replaced the anatomical superior capsule (Figures 1A, 1B). Some cases included biceps tenotomy, subscapularis repair, or infraspinatus repair.

Medial fixation was obtained with a PASTA (partial articular supraspinatus tendon avulsion) bridge-type construct¹⁵ that consisted of two 3.0-mm BioComposite SutureTak anchors (placed medially on the glenoid rim, medial to the labrum) and a 3.5-mm BioComposite Vented SwiveLock. In some cases, a significant amount of tissue was present medially, and the third anchor was not used; instead, a double surgeon knot was used to fixate the double pulley medially.

Posterior margin convergence (PMC) was performed in all cases. Anterior margin convergence (AMC) was performed in only 3 cases.

Clinical Evaluation

All patients who underwent SCR were followed prospectively, and all signed an informed consent form. Between 2014 and the time of this study, 9 patients had surgery with a minimum 2-year follow-up. Before surgery, all patients received a diagnosis of full-thickness RCT with decreased acromial-humeral distance (AHD). One patient had RTSA 18 months after surgery, did not reach the 2-year follow-up, and was excluded from the data analysis. Patients were clinically evaluated on the 100-point American Shoulder and Elbow Surgeons (ASES) shoulder index and on a 10-point VAS for pain—before surgery, monthly for the first 6 months after surgery, then every 6 months until 2 years after surgery, and yearly thereafter. These patients were compared with Dr. Hirahara’s historical control patients, who had undergone repair of massive RCTs. Mean graft size was calculated and reported. Cases were separated and analyzed on the basis of whether AMC was performed. Student t tests were used to determine statistical differences between study patients’ preoperative and postoperative scores, between study and historical control patients, and between patients who had AMC performed and those who did not (P < .05).

Imaging

For all SCR patients, preoperative and postoperative radiographs were obtained in 2 planes: anterior-posterior with arm in neutral rotation, and scapular Y. On anteroposterior radiographs, AHD was measured from the most proximal aspect of the humeral head in a vertical line to the most inferior portion of the acromion (Figures 2A, 2B).

Results

The Table provides an overview of the study results. Eight patients (6 men, 2 women) met the final inclusion criteria for postoperative ASES and VAS data analysis.

AHD was measured on a standard anteroposterior radiograph in neutral rotation. The Hamada grading scale16 was used to classify the massive RCTs before and after surgery. Before surgery, 4 were grade 4A, 1 grade 3, 2 grade 2, and 1 grade 1; immediately after surgery, all were grade 1 (AHD, ≥6 mm). Two years after surgery, 1 patient had an AHD of 4.6 mm after a failure caused by a fall. Mean (SD) preoperative AHD was 4.50 (2.25) mm (range, 1.7-7.9 mm). Radiographs obtained immediately (mean, 1.22 months; range, 1 day-2.73 months) after surgery showed AHD was significantly (P < .0008) increased (mean, 8.48 mm; SD, 1.25 mm; range, 6.0-10.0 mm) (Figure 5).

Mean graft size was 2.9 mm medial × 3.6 mm lateral × 5.4 mm anterior × 5.4 mm posterior. Three patients had AMC performed. There was a significant (P < .05) difference in ASES scores between patients who had AMC performed (93) and those who did not (77).

Ultrasonography

Two weeks to 2 months after surgery, all patients had an intact capsular graft and no pulsatile vessels on US. Between 4 months and 10 months, US showed the construct intact laterally in all cases, a pulsatile vessel in the graft at the tuberosity (evidence of blood flow) in 4 of 5 cases, and a pulsatile vessel hypertrophied in 2 cases (Figures 6A, 6B).

Magnetic Resonance Imaging

Before surgery, 4 patients had Goutallier¹⁷ stage 4 rotator cuff muscle degeneration, 2 had stage 3 degeneration, and 2 had stage 2 degeneration. Throughout the follow-up period, US was as effective as MRI in determining graft integrity, graft thickness, and greater tuberosity fixation. Therefore, the SCRs were assessed primarily with US. MRI was ordered only if a failure was suspected or if the patient had some form of trauma. A total of 7 MRIs were ordered for 5 of the 8 patients in the study. The graft was intact in 4 of the 5 (Figures 7A-7C) and ruptured in the fifth.

Discussion

Mihata and colleagues¹⁰ published 2-year data for their reconstructive procedure with fascia lata autograft. In a modification of their procedure, Dr. Hirahara used dermal allograft to recreate the superior capsule.¹¹ The results of the present 2-year study mirror the clinical outcomes reported by Mihata and colleagues¹⁰ and confirm that SCR improves functional outcomes and increases AHD regardless of graft type used.

The outcomes of the SCR patients in our study were significantly better than the outcomes of the historical control patients, who underwent repair of massive RCTs. Although there was no significant difference in the 2 groups’ ASES scores, the control patients had significantly higher postoperative VAS pain scores. We think that, as more patients undergo SCR and the population sample increases, we will see a significant difference in ASES scores as well (our SCR patients already showed a trend toward improved ASES scores).

Compared with RTSA, SCR has fewer risks and fewer complications and does not limit further surgical options.^8,9,18 The 9 patients who had surgery with a minimum 2-year follow-up in our study had 4 complications. Six months after surgery, 1 patient fell and tore the infraspinatus and subscapularis muscles. Outcomes continued to improve, and no issues were reported, despite a decrease in AHD, from 8 mm immediately after surgery to 4.6 mm 2 years after surgery.

Two patients were in motor vehicle accidents. In 1 case, the accident occurred about 2 months after surgery. This patient also sustained a possible injury in a fall after receiving general anesthesia for a dental procedure. After having done very well the preceding months, the patient now reported increasing pain and dysfunction. MRI showed loss of glenoid fixation. Improved ASES and VAS pain scores were maintained throughout the follow-up period. AHD was increased at 13 months and mildly decreased at 2 years. Glenoid fixation was obtained with 2 anchors and a double surgeon knot. When possible, however, it is best to add an anchor and double-row fixation, as 3 anchors and a double-row construct are biomechanically stronger.^19-24

The other motor vehicle accident occurred about 23 months after surgery. Two months later, a graft rupture was found on US and MRI, but the patient was maintaining full range of motion, AHD, and improved strength. The 1.5-mm graft in this patient was thinner than the 3.5-mm grafts in the rest of the study group. This was the only patient who developed a graft rupture rather than loss of fixation.

If only patients with graft thickness >3.0 mm are included in the data analysis, mean ASES score rises to 89.76, and mean VAS pain score drops to 0. Therefore, we argue against using a graft thinner than 3.5 mm. Our excellent study results indicate that larger grafts are unnecessary. Mihata and colleagues¹⁰ used fascia lata grafts of 6 mm to 8 mm. Ultimate load to failure is significantly higher for dermal allograft than for fascia lata graft.²⁵ In SCR, the stronger dermal allograft withstands applied forces and repeated deformations and has excellent clinical outcomes.

Only 1 patient had a failure that required RTSA. VAS pain scores were lower and ASES scores were improved the first year after surgery, but then function deteriorated. The patient said there was no specific precipitating incident. Computed tomography arthrogram, ordered to assess the construct, showed anterior and superior subluxation of the humeral head, even with an intact subscapularis tendon—an indication of underlying instability, which most likely caused the failure. Eighteen months after surgery, the patient was able to undergo RTSA. On further evaluation of this patient’s procedure, it was determined that the graft needed better fixation anteriorly.

Mihata and colleagues^10,12,14 indicated that AMC was unnecessary, and our procedure did not require it. However, data in our prospective evaluation began showing improved outcomes with AMC. As dermal allograft is more elastic than fascia lata autograft,²⁵ we concluded that graft tensioning is key to the success of this procedure. Graft tension depends on many factors, including exact measurement of the distances between the anchors to punch holes in the graft, arm position to set the relationship between the anchor distances, and AMC and PMC. We recommend placing the arm in neutral rotation, neutral flexion, and abduction with the patient at rest, based on the size of the patient’s latissimus dorsi. Too much abduction causes overtensioning, and excess rotation or flexion-extension changes the distance between the glenoid and the greater tuberosity asymmetrically, from anterior to posterior. With the arm in neutral position, distances between anchors are accurately measured, and these measurements are used to determine graft size.

Graft tension is also needed to control the amount of elasticity allowed by the graft and thereby maintain stability, as shown by the Poisson ratio, the ratio of transverse contraction to longitudinal extension on a material in the presence of a stretching force. As applied to SCR, it is the ratio of mediolateral elasticity to anteroposterior deformation or constraint. If the graft is appropriately secured in the anteroposterior direction by way of ACM and PMC, elongation in the medial-lateral direction will be limited—reducing the elasticity of the graft, improving overall stability, and ultimately producing better clinical outcomes. This issue was discussed by Burkhart and colleagues²⁶ with respect to the “rotator cable complex,” which now might be best described as the “rotator-capsule cable complex.” In our study, this phenomenon was evident in the finding that patients who had AMC performed did significantly better than patients who did not have AMC performed. The ability of dermal allograft to deform in these dimensions without failure while allowing excellent range of motion makes dermal allograft an exceptional choice for grafting during SCR. Mihata25 also found dermal allograft had a clear advantage in providing better range of motion, whereas fascia lata autograft resulted in a stiffer construct. 

Dermal allograft can also incorporate into the body and transform into host tissue. The literature has described musculoskeletal US as an effective diagnostic and interventional tool.^27-31 We used it to evaluate graft size, patency, and viability. As can be seen on US, the native rotator cuff does not have any pulsatile vessels and is fed by capillary flow. Dermal allograft has native vasculature built into the tissue. After 4 months to 8 months, presence of pulsatile vessels within the graft at the greater tuberosity indicates clear revascularization and incorporation of the tissue (Figure 6B). Disappearance of pulsatile vessels on US after 1 year indicates transformation to a stabilizing structure analogous to capsule or ligament with capillary flow. US also showed graft hypertrophy after 2 years, supporting a finding of integration and growth.

Conclusion

In the past, patients with irreparable massive RCTs had few good surgical management options, RTSA being the most definitive. SCR is technically challenging and requires use of specific implantation methods but can provide patients with outstanding relief. Our clinical data showed that technically well executed SCR effectively restores the superior restraints in the glenohumeral joint and thereby increases function and decreases pain in patients with irreparable massive RCTs, even after 2 years.

Take-Home Points

• The SCR is a viable treatment option for massive, irreparable RCTs.
• Arm position and exact measurement between anchors will help ensure proper graft tensioning.
• Anterior and posterior tension and margin convergence are critical to stabilizing the graft.
• Acromial-humeral distance, ASES, and VAS scores are improved and maintained over long-term follow-up.
• The dermal allograft should be 3.0 mm or thicker.

Conventional treatments for irreparable massive rotator cuff tears (RCTs) have ranged from nonoperative care to débridement and biceps tenotomy,^1,2 partial cuff repair,^3,4 bridging patch grafts,⁵ tendon transfers,^6,7 and reverse total shoulder arthroplasty (RTSA).^8,9 Superior capsular reconstruction (SCR), originally described by Mihata and colleagues,¹⁰ has been developed as an alternative to these interventions. Dr. Hirahara modified the technique to use dermal allograft instead of fascia lata autograft.^10,11

Biomechanical analysis has confirmed the integral role of the superior capsule in shoulder function.^10,12-14 In the presence of a massive RCT, the humeral head migrates superiorly, causing significant pain and functional deficits, such as pseudoparalysis. It is theorized that reestablishing this important stabilizer—centering the humeral head in the glenoid and allowing the larger muscles to move the arm about a proper fulcrum—improves function and decreases pain.

Using ultrasonography (US), radiography, magnetic resonance imaging (MRI), clinical outcome scores, and a visual analog scale (VAS) for pain, we prospectively evaluated minimum 2-year clinical outcomes of performing SCR with dermal allograft for irreparable RCTs.

Methods

Except where noted otherwise, all products mentioned in this section were made by Arthrex.

Surgical Technique

The surgical technique used here was described by Hirahara and Adams.¹¹ ArthroFlex dermal allograft was attached to the greater tuberosity and the glenoid, creating a superior restraint that replaced the anatomical superior capsule (Figures 1A, 1B). Some cases included biceps tenotomy, subscapularis repair, or infraspinatus repair.

Medial fixation was obtained with a PASTA (partial articular supraspinatus tendon avulsion) bridge-type construct¹⁵ that consisted of two 3.0-mm BioComposite SutureTak anchors (placed medially on the glenoid rim, medial to the labrum) and a 3.5-mm BioComposite Vented SwiveLock. In some cases, a significant amount of tissue was present medially, and the third anchor was not used; instead, a double surgeon knot was used to fixate the double pulley medially.

Posterior margin convergence (PMC) was performed in all cases. Anterior margin convergence (AMC) was performed in only 3 cases.

Clinical Evaluation

All patients who underwent SCR were followed prospectively, and all signed an informed consent form. Between 2014 and the time of this study, 9 patients had surgery with a minimum 2-year follow-up. Before surgery, all patients received a diagnosis of full-thickness RCT with decreased acromial-humeral distance (AHD). One patient had RTSA 18 months after surgery, did not reach the 2-year follow-up, and was excluded from the data analysis. Patients were clinically evaluated on the 100-point American Shoulder and Elbow Surgeons (ASES) shoulder index and on a 10-point VAS for pain—before surgery, monthly for the first 6 months after surgery, then every 6 months until 2 years after surgery, and yearly thereafter. These patients were compared with Dr. Hirahara’s historical control patients, who had undergone repair of massive RCTs. Mean graft size was calculated and reported. Cases were separated and analyzed on the basis of whether AMC was performed. Student t tests were used to determine statistical differences between study patients’ preoperative and postoperative scores, between study and historical control patients, and between patients who had AMC performed and those who did not (P < .05).

Imaging

For all SCR patients, preoperative and postoperative radiographs were obtained in 2 planes: anterior-posterior with arm in neutral rotation, and scapular Y. On anteroposterior radiographs, AHD was measured from the most proximal aspect of the humeral head in a vertical line to the most inferior portion of the acromion (Figures 2A, 2B).

Results

The Table provides an overview of the study results. Eight patients (6 men, 2 women) met the final inclusion criteria for postoperative ASES and VAS data analysis.

AHD was measured on a standard anteroposterior radiograph in neutral rotation. The Hamada grading scale16 was used to classify the massive RCTs before and after surgery. Before surgery, 4 were grade 4A, 1 grade 3, 2 grade 2, and 1 grade 1; immediately after surgery, all were grade 1 (AHD, ≥6 mm). Two years after surgery, 1 patient had an AHD of 4.6 mm after a failure caused by a fall. Mean (SD) preoperative AHD was 4.50 (2.25) mm (range, 1.7-7.9 mm). Radiographs obtained immediately (mean, 1.22 months; range, 1 day-2.73 months) after surgery showed AHD was significantly (P < .0008) increased (mean, 8.48 mm; SD, 1.25 mm; range, 6.0-10.0 mm) (Figure 5).

Mean graft size was 2.9 mm medial × 3.6 mm lateral × 5.4 mm anterior × 5.4 mm posterior. Three patients had AMC performed. There was a significant (P < .05) difference in ASES scores between patients who had AMC performed (93) and those who did not (77).

Ultrasonography

Two weeks to 2 months after surgery, all patients had an intact capsular graft and no pulsatile vessels on US. Between 4 months and 10 months, US showed the construct intact laterally in all cases, a pulsatile vessel in the graft at the tuberosity (evidence of blood flow) in 4 of 5 cases, and a pulsatile vessel hypertrophied in 2 cases (Figures 6A, 6B).

Magnetic Resonance Imaging

Before surgery, 4 patients had Goutallier¹⁷ stage 4 rotator cuff muscle degeneration, 2 had stage 3 degeneration, and 2 had stage 2 degeneration. Throughout the follow-up period, US was as effective as MRI in determining graft integrity, graft thickness, and greater tuberosity fixation. Therefore, the SCRs were assessed primarily with US. MRI was ordered only if a failure was suspected or if the patient had some form of trauma. A total of 7 MRIs were ordered for 5 of the 8 patients in the study. The graft was intact in 4 of the 5 (Figures 7A-7C) and ruptured in the fifth.

Discussion

Mihata and colleagues¹⁰ published 2-year data for their reconstructive procedure with fascia lata autograft. In a modification of their procedure, Dr. Hirahara used dermal allograft to recreate the superior capsule.¹¹ The results of the present 2-year study mirror the clinical outcomes reported by Mihata and colleagues¹⁰ and confirm that SCR improves functional outcomes and increases AHD regardless of graft type used.

The outcomes of the SCR patients in our study were significantly better than the outcomes of the historical control patients, who underwent repair of massive RCTs. Although there was no significant difference in the 2 groups’ ASES scores, the control patients had significantly higher postoperative VAS pain scores. We think that, as more patients undergo SCR and the population sample increases, we will see a significant difference in ASES scores as well (our SCR patients already showed a trend toward improved ASES scores).

Compared with RTSA, SCR has fewer risks and fewer complications and does not limit further surgical options.^8,9,18 The 9 patients who had surgery with a minimum 2-year follow-up in our study had 4 complications. Six months after surgery, 1 patient fell and tore the infraspinatus and subscapularis muscles. Outcomes continued to improve, and no issues were reported, despite a decrease in AHD, from 8 mm immediately after surgery to 4.6 mm 2 years after surgery.

Two patients were in motor vehicle accidents. In 1 case, the accident occurred about 2 months after surgery. This patient also sustained a possible injury in a fall after receiving general anesthesia for a dental procedure. After having done very well the preceding months, the patient now reported increasing pain and dysfunction. MRI showed loss of glenoid fixation. Improved ASES and VAS pain scores were maintained throughout the follow-up period. AHD was increased at 13 months and mildly decreased at 2 years. Glenoid fixation was obtained with 2 anchors and a double surgeon knot. When possible, however, it is best to add an anchor and double-row fixation, as 3 anchors and a double-row construct are biomechanically stronger.^19-24

The other motor vehicle accident occurred about 23 months after surgery. Two months later, a graft rupture was found on US and MRI, but the patient was maintaining full range of motion, AHD, and improved strength. The 1.5-mm graft in this patient was thinner than the 3.5-mm grafts in the rest of the study group. This was the only patient who developed a graft rupture rather than loss of fixation.

If only patients with graft thickness >3.0 mm are included in the data analysis, mean ASES score rises to 89.76, and mean VAS pain score drops to 0. Therefore, we argue against using a graft thinner than 3.5 mm. Our excellent study results indicate that larger grafts are unnecessary. Mihata and colleagues¹⁰ used fascia lata grafts of 6 mm to 8 mm. Ultimate load to failure is significantly higher for dermal allograft than for fascia lata graft.²⁵ In SCR, the stronger dermal allograft withstands applied forces and repeated deformations and has excellent clinical outcomes.

Only 1 patient had a failure that required RTSA. VAS pain scores were lower and ASES scores were improved the first year after surgery, but then function deteriorated. The patient said there was no specific precipitating incident. Computed tomography arthrogram, ordered to assess the construct, showed anterior and superior subluxation of the humeral head, even with an intact subscapularis tendon—an indication of underlying instability, which most likely caused the failure. Eighteen months after surgery, the patient was able to undergo RTSA. On further evaluation of this patient’s procedure, it was determined that the graft needed better fixation anteriorly.

Mihata and colleagues^10,12,14 indicated that AMC was unnecessary, and our procedure did not require it. However, data in our prospective evaluation began showing improved outcomes with AMC. As dermal allograft is more elastic than fascia lata autograft,²⁵ we concluded that graft tensioning is key to the success of this procedure. Graft tension depends on many factors, including exact measurement of the distances between the anchors to punch holes in the graft, arm position to set the relationship between the anchor distances, and AMC and PMC. We recommend placing the arm in neutral rotation, neutral flexion, and abduction with the patient at rest, based on the size of the patient’s latissimus dorsi. Too much abduction causes overtensioning, and excess rotation or flexion-extension changes the distance between the glenoid and the greater tuberosity asymmetrically, from anterior to posterior. With the arm in neutral position, distances between anchors are accurately measured, and these measurements are used to determine graft size.

Graft tension is also needed to control the amount of elasticity allowed by the graft and thereby maintain stability, as shown by the Poisson ratio, the ratio of transverse contraction to longitudinal extension on a material in the presence of a stretching force. As applied to SCR, it is the ratio of mediolateral elasticity to anteroposterior deformation or constraint. If the graft is appropriately secured in the anteroposterior direction by way of ACM and PMC, elongation in the medial-lateral direction will be limited—reducing the elasticity of the graft, improving overall stability, and ultimately producing better clinical outcomes. This issue was discussed by Burkhart and colleagues²⁶ with respect to the “rotator cable complex,” which now might be best described as the “rotator-capsule cable complex.” In our study, this phenomenon was evident in the finding that patients who had AMC performed did significantly better than patients who did not have AMC performed. The ability of dermal allograft to deform in these dimensions without failure while allowing excellent range of motion makes dermal allograft an exceptional choice for grafting during SCR. Mihata25 also found dermal allograft had a clear advantage in providing better range of motion, whereas fascia lata autograft resulted in a stiffer construct. 

Dermal allograft can also incorporate into the body and transform into host tissue. The literature has described musculoskeletal US as an effective diagnostic and interventional tool.^27-31 We used it to evaluate graft size, patency, and viability. As can be seen on US, the native rotator cuff does not have any pulsatile vessels and is fed by capillary flow. Dermal allograft has native vasculature built into the tissue. After 4 months to 8 months, presence of pulsatile vessels within the graft at the greater tuberosity indicates clear revascularization and incorporation of the tissue (Figure 6B). Disappearance of pulsatile vessels on US after 1 year indicates transformation to a stabilizing structure analogous to capsule or ligament with capillary flow. US also showed graft hypertrophy after 2 years, supporting a finding of integration and growth.

Conclusion

In the past, patients with irreparable massive RCTs had few good surgical management options, RTSA being the most definitive. SCR is technically challenging and requires use of specific implantation methods but can provide patients with outstanding relief. Our clinical data showed that technically well executed SCR effectively restores the superior restraints in the glenohumeral joint and thereby increases function and decreases pain in patients with irreparable massive RCTs, even after 2 years.

Take-Home Points

• The SCR is a viable treatment option for massive, irreparable RCTs.
• Arm position and exact measurement between anchors will help ensure proper graft tensioning.
• Anterior and posterior tension and margin convergence are critical to stabilizing the graft.
• Acromial-humeral distance, ASES, and VAS scores are improved and maintained over long-term follow-up.
• The dermal allograft should be 3.0 mm or thicker.

Conventional treatments for irreparable massive rotator cuff tears (RCTs) have ranged from nonoperative care to débridement and biceps tenotomy,^1,2 partial cuff repair,^3,4 bridging patch grafts,⁵ tendon transfers,^6,7 and reverse total shoulder arthroplasty (RTSA).^8,9 Superior capsular reconstruction (SCR), originally described by Mihata and colleagues,¹⁰ has been developed as an alternative to these interventions. Dr. Hirahara modified the technique to use dermal allograft instead of fascia lata autograft.^10,11

Biomechanical analysis has confirmed the integral role of the superior capsule in shoulder function.^10,12-14 In the presence of a massive RCT, the humeral head migrates superiorly, causing significant pain and functional deficits, such as pseudoparalysis. It is theorized that reestablishing this important stabilizer—centering the humeral head in the glenoid and allowing the larger muscles to move the arm about a proper fulcrum—improves function and decreases pain.

Using ultrasonography (US), radiography, magnetic resonance imaging (MRI), clinical outcome scores, and a visual analog scale (VAS) for pain, we prospectively evaluated minimum 2-year clinical outcomes of performing SCR with dermal allograft for irreparable RCTs.

Methods

Except where noted otherwise, all products mentioned in this section were made by Arthrex.

Surgical Technique

The surgical technique used here was described by Hirahara and Adams.¹¹ ArthroFlex dermal allograft was attached to the greater tuberosity and the glenoid, creating a superior restraint that replaced the anatomical superior capsule (Figures 1A, 1B). Some cases included biceps tenotomy, subscapularis repair, or infraspinatus repair.

Medial fixation was obtained with a PASTA (partial articular supraspinatus tendon avulsion) bridge-type construct¹⁵ that consisted of two 3.0-mm BioComposite SutureTak anchors (placed medially on the glenoid rim, medial to the labrum) and a 3.5-mm BioComposite Vented SwiveLock. In some cases, a significant amount of tissue was present medially, and the third anchor was not used; instead, a double surgeon knot was used to fixate the double pulley medially.

Posterior margin convergence (PMC) was performed in all cases. Anterior margin convergence (AMC) was performed in only 3 cases.

Clinical Evaluation

All patients who underwent SCR were followed prospectively, and all signed an informed consent form. Between 2014 and the time of this study, 9 patients had surgery with a minimum 2-year follow-up. Before surgery, all patients received a diagnosis of full-thickness RCT with decreased acromial-humeral distance (AHD). One patient had RTSA 18 months after surgery, did not reach the 2-year follow-up, and was excluded from the data analysis. Patients were clinically evaluated on the 100-point American Shoulder and Elbow Surgeons (ASES) shoulder index and on a 10-point VAS for pain—before surgery, monthly for the first 6 months after surgery, then every 6 months until 2 years after surgery, and yearly thereafter. These patients were compared with Dr. Hirahara’s historical control patients, who had undergone repair of massive RCTs. Mean graft size was calculated and reported. Cases were separated and analyzed on the basis of whether AMC was performed. Student t tests were used to determine statistical differences between study patients’ preoperative and postoperative scores, between study and historical control patients, and between patients who had AMC performed and those who did not (P < .05).

Imaging

For all SCR patients, preoperative and postoperative radiographs were obtained in 2 planes: anterior-posterior with arm in neutral rotation, and scapular Y. On anteroposterior radiographs, AHD was measured from the most proximal aspect of the humeral head in a vertical line to the most inferior portion of the acromion (Figures 2A, 2B).

Results

The Table provides an overview of the study results. Eight patients (6 men, 2 women) met the final inclusion criteria for postoperative ASES and VAS data analysis.

AHD was measured on a standard anteroposterior radiograph in neutral rotation. The Hamada grading scale16 was used to classify the massive RCTs before and after surgery. Before surgery, 4 were grade 4A, 1 grade 3, 2 grade 2, and 1 grade 1; immediately after surgery, all were grade 1 (AHD, ≥6 mm). Two years after surgery, 1 patient had an AHD of 4.6 mm after a failure caused by a fall. Mean (SD) preoperative AHD was 4.50 (2.25) mm (range, 1.7-7.9 mm). Radiographs obtained immediately (mean, 1.22 months; range, 1 day-2.73 months) after surgery showed AHD was significantly (P < .0008) increased (mean, 8.48 mm; SD, 1.25 mm; range, 6.0-10.0 mm) (Figure 5).

Mean graft size was 2.9 mm medial × 3.6 mm lateral × 5.4 mm anterior × 5.4 mm posterior. Three patients had AMC performed. There was a significant (P < .05) difference in ASES scores between patients who had AMC performed (93) and those who did not (77).

Ultrasonography

Two weeks to 2 months after surgery, all patients had an intact capsular graft and no pulsatile vessels on US. Between 4 months and 10 months, US showed the construct intact laterally in all cases, a pulsatile vessel in the graft at the tuberosity (evidence of blood flow) in 4 of 5 cases, and a pulsatile vessel hypertrophied in 2 cases (Figures 6A, 6B).

Magnetic Resonance Imaging

Before surgery, 4 patients had Goutallier¹⁷ stage 4 rotator cuff muscle degeneration, 2 had stage 3 degeneration, and 2 had stage 2 degeneration. Throughout the follow-up period, US was as effective as MRI in determining graft integrity, graft thickness, and greater tuberosity fixation. Therefore, the SCRs were assessed primarily with US. MRI was ordered only if a failure was suspected or if the patient had some form of trauma. A total of 7 MRIs were ordered for 5 of the 8 patients in the study. The graft was intact in 4 of the 5 (Figures 7A-7C) and ruptured in the fifth.

Discussion

Mihata and colleagues¹⁰ published 2-year data for their reconstructive procedure with fascia lata autograft. In a modification of their procedure, Dr. Hirahara used dermal allograft to recreate the superior capsule.¹¹ The results of the present 2-year study mirror the clinical outcomes reported by Mihata and colleagues¹⁰ and confirm that SCR improves functional outcomes and increases AHD regardless of graft type used.

The outcomes of the SCR patients in our study were significantly better than the outcomes of the historical control patients, who underwent repair of massive RCTs. Although there was no significant difference in the 2 groups’ ASES scores, the control patients had significantly higher postoperative VAS pain scores. We think that, as more patients undergo SCR and the population sample increases, we will see a significant difference in ASES scores as well (our SCR patients already showed a trend toward improved ASES scores).

Compared with RTSA, SCR has fewer risks and fewer complications and does not limit further surgical options.^8,9,18 The 9 patients who had surgery with a minimum 2-year follow-up in our study had 4 complications. Six months after surgery, 1 patient fell and tore the infraspinatus and subscapularis muscles. Outcomes continued to improve, and no issues were reported, despite a decrease in AHD, from 8 mm immediately after surgery to 4.6 mm 2 years after surgery.

Two patients were in motor vehicle accidents. In 1 case, the accident occurred about 2 months after surgery. This patient also sustained a possible injury in a fall after receiving general anesthesia for a dental procedure. After having done very well the preceding months, the patient now reported increasing pain and dysfunction. MRI showed loss of glenoid fixation. Improved ASES and VAS pain scores were maintained throughout the follow-up period. AHD was increased at 13 months and mildly decreased at 2 years. Glenoid fixation was obtained with 2 anchors and a double surgeon knot. When possible, however, it is best to add an anchor and double-row fixation, as 3 anchors and a double-row construct are biomechanically stronger.^19-24

The other motor vehicle accident occurred about 23 months after surgery. Two months later, a graft rupture was found on US and MRI, but the patient was maintaining full range of motion, AHD, and improved strength. The 1.5-mm graft in this patient was thinner than the 3.5-mm grafts in the rest of the study group. This was the only patient who developed a graft rupture rather than loss of fixation.

If only patients with graft thickness >3.0 mm are included in the data analysis, mean ASES score rises to 89.76, and mean VAS pain score drops to 0. Therefore, we argue against using a graft thinner than 3.5 mm. Our excellent study results indicate that larger grafts are unnecessary. Mihata and colleagues¹⁰ used fascia lata grafts of 6 mm to 8 mm. Ultimate load to failure is significantly higher for dermal allograft than for fascia lata graft.²⁵ In SCR, the stronger dermal allograft withstands applied forces and repeated deformations and has excellent clinical outcomes.

Only 1 patient had a failure that required RTSA. VAS pain scores were lower and ASES scores were improved the first year after surgery, but then function deteriorated. The patient said there was no specific precipitating incident. Computed tomography arthrogram, ordered to assess the construct, showed anterior and superior subluxation of the humeral head, even with an intact subscapularis tendon—an indication of underlying instability, which most likely caused the failure. Eighteen months after surgery, the patient was able to undergo RTSA. On further evaluation of this patient’s procedure, it was determined that the graft needed better fixation anteriorly.

Mihata and colleagues^10,12,14 indicated that AMC was unnecessary, and our procedure did not require it. However, data in our prospective evaluation began showing improved outcomes with AMC. As dermal allograft is more elastic than fascia lata autograft,²⁵ we concluded that graft tensioning is key to the success of this procedure. Graft tension depends on many factors, including exact measurement of the distances between the anchors to punch holes in the graft, arm position to set the relationship between the anchor distances, and AMC and PMC. We recommend placing the arm in neutral rotation, neutral flexion, and abduction with the patient at rest, based on the size of the patient’s latissimus dorsi. Too much abduction causes overtensioning, and excess rotation or flexion-extension changes the distance between the glenoid and the greater tuberosity asymmetrically, from anterior to posterior. With the arm in neutral position, distances between anchors are accurately measured, and these measurements are used to determine graft size.

Graft tension is also needed to control the amount of elasticity allowed by the graft and thereby maintain stability, as shown by the Poisson ratio, the ratio of transverse contraction to longitudinal extension on a material in the presence of a stretching force. As applied to SCR, it is the ratio of mediolateral elasticity to anteroposterior deformation or constraint. If the graft is appropriately secured in the anteroposterior direction by way of ACM and PMC, elongation in the medial-lateral direction will be limited—reducing the elasticity of the graft, improving overall stability, and ultimately producing better clinical outcomes. This issue was discussed by Burkhart and colleagues²⁶ with respect to the “rotator cable complex,” which now might be best described as the “rotator-capsule cable complex.” In our study, this phenomenon was evident in the finding that patients who had AMC performed did significantly better than patients who did not have AMC performed. The ability of dermal allograft to deform in these dimensions without failure while allowing excellent range of motion makes dermal allograft an exceptional choice for grafting during SCR. Mihata25 also found dermal allograft had a clear advantage in providing better range of motion, whereas fascia lata autograft resulted in a stiffer construct. 

Dermal allograft can also incorporate into the body and transform into host tissue. The literature has described musculoskeletal US as an effective diagnostic and interventional tool.^27-31 We used it to evaluate graft size, patency, and viability. As can be seen on US, the native rotator cuff does not have any pulsatile vessels and is fed by capillary flow. Dermal allograft has native vasculature built into the tissue. After 4 months to 8 months, presence of pulsatile vessels within the graft at the greater tuberosity indicates clear revascularization and incorporation of the tissue (Figure 6B). Disappearance of pulsatile vessels on US after 1 year indicates transformation to a stabilizing structure analogous to capsule or ligament with capillary flow. US also showed graft hypertrophy after 2 years, supporting a finding of integration and growth.

Conclusion

In the past, patients with irreparable massive RCTs had few good surgical management options, RTSA being the most definitive. SCR is technically challenging and requires use of specific implantation methods but can provide patients with outstanding relief. Our clinical data showed that technically well executed SCR effectively restores the superior restraints in the glenohumeral joint and thereby increases function and decreases pain in patients with irreparable massive RCTs, even after 2 years.

Take-Home Points

• The optimal centrifugation protocol for production of rat PRP is 1300 rpm for 5 minutes.
• PRP administration in RCR improves tendon biomechanics in a rat model.
• Administration of NSAIDs following RCR has no significant effect on tendon biomechanical properties.
• NSAIDs may be co-administered with PRP without reducing efficacy of PRP.
• The role of PRP and NSAIDs in human RCR remains unclear.

Rotator cuff tears are a common source of shoulder pain and disability among older adults and athletes. Full-thickness tears alone occur in up to 30% of adults older than 60 years.¹ Surgical repair is plagued by an unpredictable rate of recurrence (range, 11%-94%).^1-10 As a result of improved suture materials, knotting patterns, and anchor designs, hardware issues are no longer the primary cause of rotator cuff repair (RCR) failures; now the principal mode of failure is biologic.² Animal model studies have found that, after injury and subsequent healing, the tendon–bone interface remains abnormal.¹¹ Rotator cuff research therefore has focused largely on biological enhancement of tendon-to-bone healing.

One means of biological augmentation is autologous platelet-rich plasma (PRP), which has supraphysiologic concentrations of platelets and their secreted growth factors. Although there is no consensus on the long-term efficacy of PRP, some studies suggest PRP accelerates healing over short and intermediate terms, which may contribute to a more rapid decrease in pain and more rapid return to normal activities.^12-18 Similarly, systemic nonsteroidal anti-inflammatory drugs (NSAIDs) have long been used to treat musculoskeletal injuries, including rotator cuff pathology. However, NSAIDs inhibit cyclooxygenase activity, and clinical and experimental data have shown that cyclooxygenase 2 function is crucial in normal tendon-to-bone healing.^19-21

Comprehensive studies have been conducted on the efficacy of both PRP and NSAIDs, but the interaction of concurrently used PRP and NSAIDs has not been determined. As many physicians use both modalities in the treatment of soft-tissue injuries, it is important to study the potential interactions when coadministered. Prior studies in small animal models suggest NSAIDs may impair tendon-to-bone healing in RCR, but there is no evidence regarding the effect of NSAIDs on the efficacy of PRP treatment.²¹

We conducted a study to determine the interaction of PRP and NSAIDs when used as adjuncts to RCR in a rat model. We hypothesized that PRP would increase the strength of RCR and that NSAIDs would interfere with the effects of PRP. A preliminary study objective was to determine an appropriate centrifugation protocol for producing PRP from rat blood, for use in this study and in future rat-based studies of PRP.

Materials and Methods

Part A: Pretesting Determination of PRP Centrifugation Protocol

Fourteen adult male Fischer rats were used in part A of this study, which was conducted to determine an appropriate PRP centrifugation protocol. Traditional PRP centrifugation protocols are established for human blood, but rat red blood cells (RBCs) and human RBCs differ in size.²² In our preliminary study, we wanted to determine the adjusted centrifuge speed and duration for producing clinically optimal PRP from rats. Clinically optimal PRP has reduced levels of RBCs, which decrease platelet affinity. Although the role of leukocytes in PRP preparations is debated, reducing the number of white blood cells (WBCs) decreases the number of matrix metalloproteinases and reactive oxygen species that may lead to inflammation. We used the platelet index (ratio of platelets to WBCs) and the RBC count to quantify the quality of our PRP sample.

Each rat in part A was anesthetized while supine. We used the Autologous Conditioned Plasma (ACP) system (Arthrex), which requires only 1 centrifugation cycle to create PRP. About 9 mL or 10 mL of blood was obtained by cardiac aspiration using an ACP Double Syringe (Arthrex). After blood retrieval, a thoracotomy was performed to confirm each rat’s death.

Part B: Determining the Effects of PRP and NSAIDs on RCR in a Rat Model 

Operative Cohort. Of the 34 Fischer rats used in part B of this study, 6 were used as blood donors for PRP production, and the other 28 underwent bilateral rotator cuff surgeries. We used donor rats to maximize the amount of PRP retrieval, allocating about 1 donor rat per 5 operative rats. Fischer rats are an inbred strain, so the PRP from a donor Fischer rat simulates autologous blood in other Fischer rats. Use of allogenic blood is consistent with prior rat PRP studies.^23,24

Operative Technique. Each bilateral surgery was performed by a single board-certified shoulder surgeon, and the anesthetic and surgical protocols were followed as approved by the home institution’s Institutional Animal Care and Use Committee. Before surgery, blood was harvested for PRP production from donor rats, as described earlier, and centrifuged for 5 minutes × 1300 rpm. After anesthetic induction and skin incision, the deltoid muscle was cut to expose the acromion and underlying rotator cuff. The distal supraspinatus tendon was sharply detached from the greater tuberosity. A bone-tunnel RCR was performed by drilling a transverse tunnel across the greater tuberosity and affixing the tendon to its footprint with a 5-0 polypropylene suture (Prolene; Ethicon). Each rat was then randomly assigned to receive 50 µL of donor PRP injected in 1 operative shoulder and saline in the contralateral shoulder. Injections were made in the supraspinatus tendon at its attachment to the humerus. Deltoid and skin were closed with 4-0 polyglactin (Vicryl) suture (Ethicon) and staples, respectively.

Tendon Preparation. Immediately post mortem, each shoulder was grossly dissected to isolate the supraspinatus muscle attached to the humerus. Shoulders were then frozen in 0.15-M saline solution until specified biomechanical testing dates.

On day of dimensional/biomechanical testing, each specimen was thawed at room temperature and finely dissected under a microscope (Stemi 200-C; Car Zeiss). After dissection, the humeral shaft was embedded in polymethylmethacrylate within a test tube. The free end of the supraspinatus tendon was glued within a “tab” of waterproofed emery cloth, leaving about 2 mm of tendon between the tab and the greater tuberosity. 

Biomechanical Analysis. A 5848 MicroTester (Instron) was used for biomechanical testing. Each tabbed tendon, held by a pneumatic clamp attached to the MicroTester, was tested in a preconditioning phase and then a ramp-to-failure phase. A constant drip of 0.15-M saline was run through the apparatus to simulate physiologic hydration of tissue. After the embedded specimen was secure within the loading apparatus, an initial tensile preload of 0.2 N was applied. After preloading, the tendon was run through a preconditioning phase to account for viscoelastic relaxation. Immediately after preconditioning, each tendon was subjected to failure testing at a ramp rate of 0.1 mm/s. Force data were collected as a function of displacement, allowing for the calculation of 4 biomechanical parameters: failure force, tendon stiffness and normalized stiffness, energy to failure, and total energy. Tendon stiffness is the slope of a curve-fit line of the initial peak; failure force is the force of the highest peak; energy to failure is the area under the curve (AUC) to the highest peak; and total energy is the AUC from the start of failure ramping to the point at which the tendon is torn off completely. Two-way ANOVA was used to assess the differences between treatment groups and diet groups for all parameters. Statistical significance was set at P < .05.

A power analysis was performed to determine ability to detect differences between cohorts. For power of 80% and P = .05, a difference of 16% of the mean could be detected for failure force, 30% for energy to failure, 14% for total energy to failure, and 24% for stiffness. In addition, a difference of 4% of the mean could be detected for tendon length, 6% for width, and 10% for thickness.

Results

Across all collective treatment-diet groups and biomechanical parameters, there was only 1 statistically significant difference. Mean (SD) energy to failure was significantly higher (P = .03) in shoulders treated with PRP, 11.7 (7.3) N-mm, than in those treated without PRP, 8.7 (4.6) N-mm (Figure 4). There were no statistically significant differences between shoulders treated with indomethacin and those treated without indomethacin (Table 3), and no statistically significant relationships between treatment and drug for any other biomechanical parameter (Figures 5-7).

Discussion

Our preliminary objective in this study was to determine the optimal centrifugation protocol for producing rat-based PRP. Optimal PRP requires a dense concentration of platelets as well as reduced levels of RBCs and WBCs.²⁵ We used the platelet index to quantify the quality of our PRP samples, and we obtained the highest platelet index for the protocol of 5 minutes × 1300 rpm. This finding may be useful in later rat studies involving PRP.

The primary objective of this study was to assess the effect of the interaction of PRP and NSAIDs on RCR. PRP has been found to augment RCR,^12,26,27 but indomethacin may impair healing.^21,25 We hypothesized that shoulders treated with PRP would have more biomechanical strength than control shoulders and that indomethacin would decrease biomechanical strength. 

Our data showed increased energy to failure of the rotator cuff with PRP injections (P = .03). All other biomechanical parameters showed no significant differences with PRP treatment, though there were statistically insignificant trends of increased total energy, failure force, and stiffness in the PRP cohorts. There were no statistically significant differences between the indomethacin and no-indomethacin groups, and indomethacin had no effect on the efficacy of PRP treatment. It should be noted that the measurements of total energy, energy to failure, and failure force best reflect the strength of the tendon–bone interface. Other biomechanical measures, such as stiffness and normalized stiffness, are physical properties of the tendon itself and apply less to enthesis strength, which was the primary focus of this study.

Beck and colleagues²³ studied the effect of allogeneic PRP on RCR in a rat model. They tested biomechanical and histologic outcomes 7, 14, and 21 days after surgery. There was no significant difference in failure load between the 2 groups at any time point. Compared with failure strain in the control group, failure strain in the PRP group was decreased at 7 days, normalized at 14 days, and increased at 21 days. The authors hypothesized that increased tendon failure strain at 21 days may have reduced forces being transmitted to the suture fixation site, which may be clinically significant and warrants further investigation. In a similar study, by Dolkart and colleagues,²⁸ intraoperative PRP administration enhanced the maximal load-to-failure and stiffness of rats’ repaired rotator cuffs. On histologic examination, tendons treated with PRP (vs control tendons) had more organized collagen. Although these studies have limitations similar to our study, these results further support improved tendon-to-bone healing with PRP.

In clinical application, Barber and colleagues²⁶ found that, compared with controls, suturing PRP fibrin matrix into the rotator cuff during repair decreased the incidence of magnetic resonance imaging–detected retears. However, in 2 prospective, randomized trials, Castricini and colleagues²⁹ and Weber and colleagues³⁰ found that use of PRP in RCR did not improve outcomes. All 3 studies differ from ours in that they used fibrin matrix. However, Ersen and colleagues³¹ found no difference in the effects of PRP on rotator cuff healing between injection and fibrin matrix; PRP improved biomechanical properties of repaired rotator cuff independent of administration method. In a meta-analysis of PRP supplementation in RCR, Warth and colleagues³² found a statistically significant improvement in retear rates for tears >3 cm repaired with a double-row technique, but otherwise no overall improvement in retear rates or outcome scores with PRP. The authors acknowledged that the significant heterogeneity of the studies in their meta-analysis may have affected the quality of their data.

Although our study provides some insight into the effectiveness of PRP in tendon repair, the lack of standardization in PRP preparation and time points tested makes comparisons with similar studies difficult.³³ Recent reports have emphasized that not all PRP separation systems yield similar products.³³ Platelet concentrations, and therefore platelet-derived growth factor concentrations, differ between systems and may yield different clinical outcomes. Our decision to use leukocyte-reduced PRP is supported by a meta-analysis by Riboh and colleagues,³⁴ who reviewed the literature on the effect of leukocyte concentration on the efficacy of PRP products. They found that, in the treatment of knee osteoarthritis, use of leukocyte-poor PRP resulted in improved functional outcomes scores in comparison with placebo, but this improvement did not occur with leukocyte-rich PRP. However, there is still no consensus on optimal preparation, dosing, and route of administration of PRP, and preparations described in the literature vary.

This study also assessed the interaction of PRP and NSAIDs. Although there were no statistically significant differences between treatment and diet, shoulders treated with indomethacin alone showed a trend toward weaker biomechanical parameters in comparison with shoulders treated with saline alone, with PRP alone, or with both PRP and indomethacin. A larger sample would be needed to establish statistical significance. These trends are not surprising, as Cohen and colleagues²¹ found that NSAIDs, specifically indomethacin and celecoxib, significantly inhibited rotator cuff tendon-to-bone healing. The authors also found that a 2-week course of indomethacin was sufficient to significantly inhibit tendon-to-bone healing. In fact, although the drugs were discontinued after 14 days, biomechanical properties were negatively affected up to 8 weeks after repair. Our results differ from theirs even though the 2 studies used similar doses and administration protocols.

One strength of this study was that all surgeries were performed by a single board-certified surgeon using a standardized technique. In addition, a control group was established, and personnel and techniques for all fine dissections and biomechanical tests were consistent throughout. Blinded randomization and diet normalization, as well as adequate power for detecting significant effects, strengthened the study as well.

The study had several limitations. First, whereas most human rotator cuff tears are chronic, we used a model of acute injury and repair. As acute tears that are immediately repaired are more likely to heal, detection of differences between cohorts is less likely. However, using an acute model is still the most reliable strategy for inducing a controlled injury with reproducible severity. Second, we analyzed data at only 1 time point, which may not provide an accurate representation of long-term effects. Third, systemic administration of indomethacin did not allow for intra-rat shoulder comparisons of the different drug groups. Fourth, although it is possible that the dosage of NSAID was insufficient to produce significant differences in biomechanics, our dosage was consistent with that used in a study that found a significant effect on tendon healing.²¹

Conclusion

Our study found that the strength of the supraspinatus tendon enthesis as defined by energy to failure was increased with intratendinous PRP injection. Indomethacin showed no statistical effect, but there was a trend toward reduced strength after repair. However, the extent to which coadministration of indomethacin affects PRP remains unclear, and these data cannot necessarily be extrapolated to the typical human rotator cuff tear caused by chronic repetitive stress.

Take-Home Points

• The optimal centrifugation protocol for production of rat PRP is 1300 rpm for 5 minutes.
• PRP administration in RCR improves tendon biomechanics in a rat model.
• Administration of NSAIDs following RCR has no significant effect on tendon biomechanical properties.
• NSAIDs may be co-administered with PRP without reducing efficacy of PRP.
• The role of PRP and NSAIDs in human RCR remains unclear.

Rotator cuff tears are a common source of shoulder pain and disability among older adults and athletes. Full-thickness tears alone occur in up to 30% of adults older than 60 years.¹ Surgical repair is plagued by an unpredictable rate of recurrence (range, 11%-94%).^1-10 As a result of improved suture materials, knotting patterns, and anchor designs, hardware issues are no longer the primary cause of rotator cuff repair (RCR) failures; now the principal mode of failure is biologic.² Animal model studies have found that, after injury and subsequent healing, the tendon–bone interface remains abnormal.¹¹ Rotator cuff research therefore has focused largely on biological enhancement of tendon-to-bone healing.

One means of biological augmentation is autologous platelet-rich plasma (PRP), which has supraphysiologic concentrations of platelets and their secreted growth factors. Although there is no consensus on the long-term efficacy of PRP, some studies suggest PRP accelerates healing over short and intermediate terms, which may contribute to a more rapid decrease in pain and more rapid return to normal activities.^12-18 Similarly, systemic nonsteroidal anti-inflammatory drugs (NSAIDs) have long been used to treat musculoskeletal injuries, including rotator cuff pathology. However, NSAIDs inhibit cyclooxygenase activity, and clinical and experimental data have shown that cyclooxygenase 2 function is crucial in normal tendon-to-bone healing.^19-21

Comprehensive studies have been conducted on the efficacy of both PRP and NSAIDs, but the interaction of concurrently used PRP and NSAIDs has not been determined. As many physicians use both modalities in the treatment of soft-tissue injuries, it is important to study the potential interactions when coadministered. Prior studies in small animal models suggest NSAIDs may impair tendon-to-bone healing in RCR, but there is no evidence regarding the effect of NSAIDs on the efficacy of PRP treatment.²¹

We conducted a study to determine the interaction of PRP and NSAIDs when used as adjuncts to RCR in a rat model. We hypothesized that PRP would increase the strength of RCR and that NSAIDs would interfere with the effects of PRP. A preliminary study objective was to determine an appropriate centrifugation protocol for producing PRP from rat blood, for use in this study and in future rat-based studies of PRP.

Materials and Methods

Part A: Pretesting Determination of PRP Centrifugation Protocol

Fourteen adult male Fischer rats were used in part A of this study, which was conducted to determine an appropriate PRP centrifugation protocol. Traditional PRP centrifugation protocols are established for human blood, but rat red blood cells (RBCs) and human RBCs differ in size.²² In our preliminary study, we wanted to determine the adjusted centrifuge speed and duration for producing clinically optimal PRP from rats. Clinically optimal PRP has reduced levels of RBCs, which decrease platelet affinity. Although the role of leukocytes in PRP preparations is debated, reducing the number of white blood cells (WBCs) decreases the number of matrix metalloproteinases and reactive oxygen species that may lead to inflammation. We used the platelet index (ratio of platelets to WBCs) and the RBC count to quantify the quality of our PRP sample.

Each rat in part A was anesthetized while supine. We used the Autologous Conditioned Plasma (ACP) system (Arthrex), which requires only 1 centrifugation cycle to create PRP. About 9 mL or 10 mL of blood was obtained by cardiac aspiration using an ACP Double Syringe (Arthrex). After blood retrieval, a thoracotomy was performed to confirm each rat’s death.

Part B: Determining the Effects of PRP and NSAIDs on RCR in a Rat Model 

Operative Cohort. Of the 34 Fischer rats used in part B of this study, 6 were used as blood donors for PRP production, and the other 28 underwent bilateral rotator cuff surgeries. We used donor rats to maximize the amount of PRP retrieval, allocating about 1 donor rat per 5 operative rats. Fischer rats are an inbred strain, so the PRP from a donor Fischer rat simulates autologous blood in other Fischer rats. Use of allogenic blood is consistent with prior rat PRP studies.^23,24

Operative Technique. Each bilateral surgery was performed by a single board-certified shoulder surgeon, and the anesthetic and surgical protocols were followed as approved by the home institution’s Institutional Animal Care and Use Committee. Before surgery, blood was harvested for PRP production from donor rats, as described earlier, and centrifuged for 5 minutes × 1300 rpm. After anesthetic induction and skin incision, the deltoid muscle was cut to expose the acromion and underlying rotator cuff. The distal supraspinatus tendon was sharply detached from the greater tuberosity. A bone-tunnel RCR was performed by drilling a transverse tunnel across the greater tuberosity and affixing the tendon to its footprint with a 5-0 polypropylene suture (Prolene; Ethicon). Each rat was then randomly assigned to receive 50 µL of donor PRP injected in 1 operative shoulder and saline in the contralateral shoulder. Injections were made in the supraspinatus tendon at its attachment to the humerus. Deltoid and skin were closed with 4-0 polyglactin (Vicryl) suture (Ethicon) and staples, respectively.

Tendon Preparation. Immediately post mortem, each shoulder was grossly dissected to isolate the supraspinatus muscle attached to the humerus. Shoulders were then frozen in 0.15-M saline solution until specified biomechanical testing dates.

On day of dimensional/biomechanical testing, each specimen was thawed at room temperature and finely dissected under a microscope (Stemi 200-C; Car Zeiss). After dissection, the humeral shaft was embedded in polymethylmethacrylate within a test tube. The free end of the supraspinatus tendon was glued within a “tab” of waterproofed emery cloth, leaving about 2 mm of tendon between the tab and the greater tuberosity.