Original Research

Risk factors for dislocation after reverse total shoulder arthroplasty (RTSA) are not clearly defined. Prosthetic dislocation can result in poor patient satisfaction, worse functional outcomes, and return to the operating room.^1-3 As a result, identification of modifiable risk factors for complications represents an important research initiative for shoulder surgeons.

There is a paucity of literature devoted to the study of dislocation after RTSA. Chalmers and colleagues⁴ found a 2.9% (11/385) incidence of early dislocation within 3 months after index surgery—an improvement over the 15.8% reported for early instability over the period 2004–2006.⁵ As prosthesis design has improved and surgeons have become more comfortable with the RTSA prosthesis, surgical indications have expanded,^6,7 and dislocation rates appear to have decreased. Although the most common indication for RTSA continues to be cuff tear arthropathy (CTA),⁶ there has been increased use in rheumatoid arthritis^8-10; proximal humerus fractures, especially in cases of poor bone quality and unreliable fixation of tuberosities^11-13; and failed previous shoulder reconstruction.^14,15 As RTSA is performed more often, limiting the complications will become more important for both patient care and economics.

We conducted a study to analyze dislocation rates at our institution and to identify both modifiable and nonmodifiable risk factors for dislocation after RTSA. By identifying risk factors for dislocation, we will be able to implement additional perioperative clinical measures to reduce the incidence of dislocation.

Materials and Methods

This retrospective study of dislocation after RTSA was conducted at the Rothman Institute of Orthopedics and Methodist Hospital (Thomas Jefferson University Hospitals, Philadelphia, PA). After obtaining Institutional Review Board approval for the study, we searched our institution’s electronic database of shoulder arthroplasties to identify all RTSAs performed at our 2 large-volume urban institutions between September 27, 2010 and December 31, 2013. For the record search, International Classification of Diseases, Ninth Revision (ICD-9) codes were used (Table 1).

These unique procedure codes are used by the hospital system for billing, but are not always specific to assigned procedures. Therefore, the individual operative reports identified were reviewed to identify the patients who actually underwent RTSA. From this database, all patients who underwent RTSA were selected. Using the subpopulation of patients who underwent RTSA, we searched individual medical records to identify patients who had a dislocation after RTSA. This information was cross-referenced with ICD-9 codes for shoulder dislocation (831.0, 831.01, 831.02, 831.03) to ensure that all patients were identified.

The medical records of each patient were used to identify independent variables that could be associated with dislocation rate. Demographic variables included sex, age, and race. Preoperative clinical data included body mass index (BMI), etiology of shoulder disease leading to RTSA, individual comorbidities, and Charlson Comorbidity Index (CCI)¹⁶ modified to be used with ICD-9 codes.¹⁷ In addition, prior shoulder surgery history and arthroplasty type (primary or revision) were determined. Postoperative considerations were time to dislocation, mechanism of dislocation, and intervention(s) needed for dislocation. Although the institutional database did not include operative variables such as prosthesis type and surgical approach, all 6 surgeons in this study were using a standard deltopectoral approach in beach-chair position with a Grammont style prosthesis for RTSA cases.

Descriptive statistics for RTSA patients and the dislocation subpopulation were compiled. Bivariate analysis was used to evaluate which of the previously described variables influenced dislocation rates. Last, multivariate logistic regression analysis was performed to evaluate which factors were independent predictors of dislocation. We included demographic variables (age, sex, ethnicity), clinical variables (BMI, individual comorbidities, CCI), and surgical variables (primary vs revision, diagnosis at time of surgery). All statistical analyses were performed with Excel 2013 (Microsoft) and SPSS Statistics Version 20.0 (SPSS Inc.).

Results

From the database, we identified 487 patients who underwent 510 RTSAs during the study period. These surgeries were performed by 6 shoulder and elbow fellowship–trained surgeons. Of the 510 RTSAs, 393 (77.1%) were primary cases, and 117 (22.9%) were revision cases.

Of the 510 shoulders that underwent RTSA, 15 (2.9%; 14 patients) dislocated. Of these 15 cases, 5 were primary (1.3% of all primary cases) and 10 were revision (8.5% of all revision cases). Mean time from index surgery to diagnosis of dislocation was 58.2 days (range, 0-319 days). One dislocation occurred immediately after surgery, 2 after falls, 4 from patient-identified low-energy mechanisms of injury, and 8 without known inciting events. Nine dislocations (60%) did not have a subscapularis repair (7 were irreparable, 2 underwent subscapularis peel without repair), and the other 6 were repaired primarily (Table 2).

In addition, 11 dislocations (73.3%) previously underwent open or arthroscopic shoulder surgery. All patients who had a dislocation after RTSA returned to the operating room at least once; no dislocation was successfully treated with closed reduction in the clinic. The 15 dislocations underwent 17 surgeries: 7 isolated polyethylene exchanges, 2 isolated closed reductions, 1 hematoma aspiration with closed reduction, 1 open reduction, 2 humeral component revisions with polyethylene exchange, 1 humeral augmentation with polyethylene exchange, 2 glenosphere exchanges with polyethylene exchange, and 1 polyethylene exchange with concurrent subscapularis repair.

Male patients accounted for 32.2% of the study population but 60.0% of the dislocations (P = .019) (Table 3).

In addition, mean BMI was 33.2 for patients with dislocation and 29.5 for patients without dislocation (P = .039) (Table 3). Revision arthroplasty was found to be a risk factor for dislocation in univariate analysis: 66.7% of the dislocations occurred after revision RTSA, and only 21.6% of nondislocated shoulders were revision cases (P < .001) (Table 4).

Patients who underwent RTSA for CTA had a very low incidence of dislocation (0.35%, 1/285), accounting for 6.7% of the dislocated group and 57.6% of the nondislocated group (P < .001) (Table 4). The 1 patient with a dislocation after primary RTSA for CTA had an indolent infection at time of surgery after dislocation.

Multivariate logistic regression analysis revealed revision arthroplasty (OR = 7.515; P = .042) and increased BMI (OR = 1.09; P = .047) to be independent risk factors for dislocation after RTSA. Analysis also found a diagnosis of primary CTA to be independently associated with lower risk of dislocation after RTSA (OR = 0.025; P = .008). Last, the previously described risk factor of male sex was found not to be a significant independent risk factor, though it did trend positively (OR = 3.011; P = .071).

 

Discussion

With more RTSAs being performed, evaluation of their common complications becomes increasingly important.¹⁸ We found a 3.0% rate of dislocation after RTSA, which is consistent with the most recently reported incidence⁴ and falls within the previously described range of 0% to 8.6%.^19-26 Of the clinical risk factors identified in this study, those previously described were prior surgery, subscapularis insufficiency, higher BMI, and male sex.⁴ However, our finding of lower risk of dislocation after RTSA for primary rotator cuff pathology was not previously described. Although Chalmers and colleagues⁴ did not report this lower risk, 3 (27.3%) of their 11 patients with dislocation had primary CTA, compared with 1 (6.7%) of 15 patients in the present study.⁴ Our literature review did not identify any studies that independently reported the dislocation rate in patients who underwent RTSA for rotator cuff failure.

The risk factors of subscapularis irreparability and revision surgery suggest the importance of the soft-tissue envelope and bony anatomy in dislocation prevention. Previous analyses have suggested implant malpositioning,^27,28 poor subscapularis quality,²⁹ and inadequate muscle tensioning^5,30-32 as risk factors for RTSA. Patients with an irreparable subscapularis tendon have often had multiple surgeries with compromise to the muscle/soft-tissue envelope or bony anatomy of the shoulder. A biomechanical study by Gutiérrez and colleagues³¹ found the compressive forces of the soft tissue at the glenohumeral joint to be the most important contributor to stability in the RTSA prosthesis. In clinical studies, the role of the subscapularis in preventing instability after RTSA remains unclear. Edwards and colleagues²⁹ prospectively compared dislocation rates in patients with reparable and irreparable subscapularis tendons during RTSA and found a higher rate of dislocation in the irreparable subscapularis group. Of note, patients in the irreparable subscapularis group also had more complex diagnoses, including proximal humeral nonunion, fixed glenohumeral dislocation, and failed prior arthroplasty. Clark and colleagues³³ retrospectively analyzed subscapularis repair in 2 RTSA groups and found no appreciable effect on complication rate, dislocation events, range-of-motion gains, or pain relief.

Our finding that higher BMI is an independent risk factor was previously described.⁴ The association is unclear but could be related to implant positioning, difficulty in intraoperative assessment of muscle tensioning, or body habitus that may generate a lever arm for impingement and dislocation when the arm is in adduction. Last, our finding that male sex is a risk factor for dislocation approached significance, and this relationship was previously reported.⁴ This could be attributable to a higher rate of activity or of indolent infection in male patients.^34,35Besides studying risk factors for dislocation after RTSA, we investigated treatment. None of our patients were treated successfully and definitively with closed reduction in the clinic. This finding diverges from findings in studies by Teusink and colleagues² and Chalmers and colleagues,⁴who respectively reported 62% and 44% rates of success with closed reduction. Our cohort of 14 patients with 15 dislocations required a total of 17 trips to the operating room after dislocation. This significantly higher rate of return to the operating room suggests that dislocation after RTSA may be a more costly and morbid problem than has been previously described.

This study had several weaknesses. Despite its large consecutive series of patients, the study was retrospective, and several variables that would be documented and controlled in a prospective study could not be measured here. Specifically, neither preoperative physical examination nor patient-specific assessments of pain or function were consistently obtained. Similarly, postoperative patient-specific instruments of outcomes evaluation were not obtained consistently, so results of patients with dislocation could not be compared with those of a control group. In addition, preoperative and postoperative radiographs were not consistently present in our electronic medical records, so the influence of preoperative bony anatomy, intraoperative limb lengthening, and any implant malpositioning could not be determined. Furthermore, operative details, such as reparability of the subscapularis, were not fully available for the control group and could not be included in statistical analysis. In addition, that the known dislocation risk factor of male sex⁴ was identified here but was not significant in multivariate regression analysis suggests that this study may not have been adequately powered to identify a significant difference in dislocation rate between the sexes. Last, though our results suggested associations between the aforementioned variables and dislocation after RTSA, a truly causative relationship could not be confirmed with this study design or analysis. Therefore, our study findings are hypothesis-generating and may indicate a benefit to greater deltoid tensioning, use of retentive liners, or more conservative rehabilitation protocols for high-risk patients.

Conclusion

Dislocation after RTSA is an uncommon complication that often requires a return to the operating room. This study identified a modifiable risk factor (higher BMI) and 3 nonmodifiable risk factors (male sex, subscapularis insufficiency, revision surgery) for dislocation after RTSA. In contrast, patients who undergo RTSA for primary rotator cuff pathology are unlikely to dislocate after surgery. This low risk of dislocation after RTSA for primary cuff pathology was not previously described. Patients in the higher risk category may benefit from preoperative lifestyle modification, intraoperative techniques for increasing stability, and more conservative therapy after surgery. In addition, unlike previous investigations, this study did not find closed reduction in the clinic alone to be successful in definitively treating this patient population.

Am J Orthop. 2016;45(7):E444-E450. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.

Risk factors for dislocation after reverse total shoulder arthroplasty (RTSA) are not clearly defined. Prosthetic dislocation can result in poor patient satisfaction, worse functional outcomes, and return to the operating room.^1-3 As a result, identification of modifiable risk factors for complications represents an important research initiative for shoulder surgeons.

There is a paucity of literature devoted to the study of dislocation after RTSA. Chalmers and colleagues⁴ found a 2.9% (11/385) incidence of early dislocation within 3 months after index surgery—an improvement over the 15.8% reported for early instability over the period 2004–2006.⁵ As prosthesis design has improved and surgeons have become more comfortable with the RTSA prosthesis, surgical indications have expanded,^6,7 and dislocation rates appear to have decreased. Although the most common indication for RTSA continues to be cuff tear arthropathy (CTA),⁶ there has been increased use in rheumatoid arthritis^8-10; proximal humerus fractures, especially in cases of poor bone quality and unreliable fixation of tuberosities^11-13; and failed previous shoulder reconstruction.^14,15 As RTSA is performed more often, limiting the complications will become more important for both patient care and economics.

We conducted a study to analyze dislocation rates at our institution and to identify both modifiable and nonmodifiable risk factors for dislocation after RTSA. By identifying risk factors for dislocation, we will be able to implement additional perioperative clinical measures to reduce the incidence of dislocation.

Materials and Methods

This retrospective study of dislocation after RTSA was conducted at the Rothman Institute of Orthopedics and Methodist Hospital (Thomas Jefferson University Hospitals, Philadelphia, PA). After obtaining Institutional Review Board approval for the study, we searched our institution’s electronic database of shoulder arthroplasties to identify all RTSAs performed at our 2 large-volume urban institutions between September 27, 2010 and December 31, 2013. For the record search, International Classification of Diseases, Ninth Revision (ICD-9) codes were used (Table 1).

These unique procedure codes are used by the hospital system for billing, but are not always specific to assigned procedures. Therefore, the individual operative reports identified were reviewed to identify the patients who actually underwent RTSA. From this database, all patients who underwent RTSA were selected. Using the subpopulation of patients who underwent RTSA, we searched individual medical records to identify patients who had a dislocation after RTSA. This information was cross-referenced with ICD-9 codes for shoulder dislocation (831.0, 831.01, 831.02, 831.03) to ensure that all patients were identified.

The medical records of each patient were used to identify independent variables that could be associated with dislocation rate. Demographic variables included sex, age, and race. Preoperative clinical data included body mass index (BMI), etiology of shoulder disease leading to RTSA, individual comorbidities, and Charlson Comorbidity Index (CCI)¹⁶ modified to be used with ICD-9 codes.¹⁷ In addition, prior shoulder surgery history and arthroplasty type (primary or revision) were determined. Postoperative considerations were time to dislocation, mechanism of dislocation, and intervention(s) needed for dislocation. Although the institutional database did not include operative variables such as prosthesis type and surgical approach, all 6 surgeons in this study were using a standard deltopectoral approach in beach-chair position with a Grammont style prosthesis for RTSA cases.

Descriptive statistics for RTSA patients and the dislocation subpopulation were compiled. Bivariate analysis was used to evaluate which of the previously described variables influenced dislocation rates. Last, multivariate logistic regression analysis was performed to evaluate which factors were independent predictors of dislocation. We included demographic variables (age, sex, ethnicity), clinical variables (BMI, individual comorbidities, CCI), and surgical variables (primary vs revision, diagnosis at time of surgery). All statistical analyses were performed with Excel 2013 (Microsoft) and SPSS Statistics Version 20.0 (SPSS Inc.).

Results

From the database, we identified 487 patients who underwent 510 RTSAs during the study period. These surgeries were performed by 6 shoulder and elbow fellowship–trained surgeons. Of the 510 RTSAs, 393 (77.1%) were primary cases, and 117 (22.9%) were revision cases.

Of the 510 shoulders that underwent RTSA, 15 (2.9%; 14 patients) dislocated. Of these 15 cases, 5 were primary (1.3% of all primary cases) and 10 were revision (8.5% of all revision cases). Mean time from index surgery to diagnosis of dislocation was 58.2 days (range, 0-319 days). One dislocation occurred immediately after surgery, 2 after falls, 4 from patient-identified low-energy mechanisms of injury, and 8 without known inciting events. Nine dislocations (60%) did not have a subscapularis repair (7 were irreparable, 2 underwent subscapularis peel without repair), and the other 6 were repaired primarily (Table 2).

In addition, 11 dislocations (73.3%) previously underwent open or arthroscopic shoulder surgery. All patients who had a dislocation after RTSA returned to the operating room at least once; no dislocation was successfully treated with closed reduction in the clinic. The 15 dislocations underwent 17 surgeries: 7 isolated polyethylene exchanges, 2 isolated closed reductions, 1 hematoma aspiration with closed reduction, 1 open reduction, 2 humeral component revisions with polyethylene exchange, 1 humeral augmentation with polyethylene exchange, 2 glenosphere exchanges with polyethylene exchange, and 1 polyethylene exchange with concurrent subscapularis repair.

Male patients accounted for 32.2% of the study population but 60.0% of the dislocations (P = .019) (Table 3).

In addition, mean BMI was 33.2 for patients with dislocation and 29.5 for patients without dislocation (P = .039) (Table 3). Revision arthroplasty was found to be a risk factor for dislocation in univariate analysis: 66.7% of the dislocations occurred after revision RTSA, and only 21.6% of nondislocated shoulders were revision cases (P < .001) (Table 4).

Patients who underwent RTSA for CTA had a very low incidence of dislocation (0.35%, 1/285), accounting for 6.7% of the dislocated group and 57.6% of the nondislocated group (P < .001) (Table 4). The 1 patient with a dislocation after primary RTSA for CTA had an indolent infection at time of surgery after dislocation.

Multivariate logistic regression analysis revealed revision arthroplasty (OR = 7.515; P = .042) and increased BMI (OR = 1.09; P = .047) to be independent risk factors for dislocation after RTSA. Analysis also found a diagnosis of primary CTA to be independently associated with lower risk of dislocation after RTSA (OR = 0.025; P = .008). Last, the previously described risk factor of male sex was found not to be a significant independent risk factor, though it did trend positively (OR = 3.011; P = .071).

 

Discussion

With more RTSAs being performed, evaluation of their common complications becomes increasingly important.¹⁸ We found a 3.0% rate of dislocation after RTSA, which is consistent with the most recently reported incidence⁴ and falls within the previously described range of 0% to 8.6%.^19-26 Of the clinical risk factors identified in this study, those previously described were prior surgery, subscapularis insufficiency, higher BMI, and male sex.⁴ However, our finding of lower risk of dislocation after RTSA for primary rotator cuff pathology was not previously described. Although Chalmers and colleagues⁴ did not report this lower risk, 3 (27.3%) of their 11 patients with dislocation had primary CTA, compared with 1 (6.7%) of 15 patients in the present study.⁴ Our literature review did not identify any studies that independently reported the dislocation rate in patients who underwent RTSA for rotator cuff failure.

The risk factors of subscapularis irreparability and revision surgery suggest the importance of the soft-tissue envelope and bony anatomy in dislocation prevention. Previous analyses have suggested implant malpositioning,^27,28 poor subscapularis quality,²⁹ and inadequate muscle tensioning^5,30-32 as risk factors for RTSA. Patients with an irreparable subscapularis tendon have often had multiple surgeries with compromise to the muscle/soft-tissue envelope or bony anatomy of the shoulder. A biomechanical study by Gutiérrez and colleagues³¹ found the compressive forces of the soft tissue at the glenohumeral joint to be the most important contributor to stability in the RTSA prosthesis. In clinical studies, the role of the subscapularis in preventing instability after RTSA remains unclear. Edwards and colleagues²⁹ prospectively compared dislocation rates in patients with reparable and irreparable subscapularis tendons during RTSA and found a higher rate of dislocation in the irreparable subscapularis group. Of note, patients in the irreparable subscapularis group also had more complex diagnoses, including proximal humeral nonunion, fixed glenohumeral dislocation, and failed prior arthroplasty. Clark and colleagues³³ retrospectively analyzed subscapularis repair in 2 RTSA groups and found no appreciable effect on complication rate, dislocation events, range-of-motion gains, or pain relief.

Our finding that higher BMI is an independent risk factor was previously described.⁴ The association is unclear but could be related to implant positioning, difficulty in intraoperative assessment of muscle tensioning, or body habitus that may generate a lever arm for impingement and dislocation when the arm is in adduction. Last, our finding that male sex is a risk factor for dislocation approached significance, and this relationship was previously reported.⁴ This could be attributable to a higher rate of activity or of indolent infection in male patients.^34,35Besides studying risk factors for dislocation after RTSA, we investigated treatment. None of our patients were treated successfully and definitively with closed reduction in the clinic. This finding diverges from findings in studies by Teusink and colleagues² and Chalmers and colleagues,⁴who respectively reported 62% and 44% rates of success with closed reduction. Our cohort of 14 patients with 15 dislocations required a total of 17 trips to the operating room after dislocation. This significantly higher rate of return to the operating room suggests that dislocation after RTSA may be a more costly and morbid problem than has been previously described.

This study had several weaknesses. Despite its large consecutive series of patients, the study was retrospective, and several variables that would be documented and controlled in a prospective study could not be measured here. Specifically, neither preoperative physical examination nor patient-specific assessments of pain or function were consistently obtained. Similarly, postoperative patient-specific instruments of outcomes evaluation were not obtained consistently, so results of patients with dislocation could not be compared with those of a control group. In addition, preoperative and postoperative radiographs were not consistently present in our electronic medical records, so the influence of preoperative bony anatomy, intraoperative limb lengthening, and any implant malpositioning could not be determined. Furthermore, operative details, such as reparability of the subscapularis, were not fully available for the control group and could not be included in statistical analysis. In addition, that the known dislocation risk factor of male sex⁴ was identified here but was not significant in multivariate regression analysis suggests that this study may not have been adequately powered to identify a significant difference in dislocation rate between the sexes. Last, though our results suggested associations between the aforementioned variables and dislocation after RTSA, a truly causative relationship could not be confirmed with this study design or analysis. Therefore, our study findings are hypothesis-generating and may indicate a benefit to greater deltoid tensioning, use of retentive liners, or more conservative rehabilitation protocols for high-risk patients.

Conclusion

Dislocation after RTSA is an uncommon complication that often requires a return to the operating room. This study identified a modifiable risk factor (higher BMI) and 3 nonmodifiable risk factors (male sex, subscapularis insufficiency, revision surgery) for dislocation after RTSA. In contrast, patients who undergo RTSA for primary rotator cuff pathology are unlikely to dislocate after surgery. This low risk of dislocation after RTSA for primary cuff pathology was not previously described. Patients in the higher risk category may benefit from preoperative lifestyle modification, intraoperative techniques for increasing stability, and more conservative therapy after surgery. In addition, unlike previous investigations, this study did not find closed reduction in the clinic alone to be successful in definitively treating this patient population.

Am J Orthop. 2016;45(7):E444-E450. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.

Risk factors for dislocation after reverse total shoulder arthroplasty (RTSA) are not clearly defined. Prosthetic dislocation can result in poor patient satisfaction, worse functional outcomes, and return to the operating room.^1-3 As a result, identification of modifiable risk factors for complications represents an important research initiative for shoulder surgeons.

There is a paucity of literature devoted to the study of dislocation after RTSA. Chalmers and colleagues⁴ found a 2.9% (11/385) incidence of early dislocation within 3 months after index surgery—an improvement over the 15.8% reported for early instability over the period 2004–2006.⁵ As prosthesis design has improved and surgeons have become more comfortable with the RTSA prosthesis, surgical indications have expanded,^6,7 and dislocation rates appear to have decreased. Although the most common indication for RTSA continues to be cuff tear arthropathy (CTA),⁶ there has been increased use in rheumatoid arthritis^8-10; proximal humerus fractures, especially in cases of poor bone quality and unreliable fixation of tuberosities^11-13; and failed previous shoulder reconstruction.^14,15 As RTSA is performed more often, limiting the complications will become more important for both patient care and economics.

We conducted a study to analyze dislocation rates at our institution and to identify both modifiable and nonmodifiable risk factors for dislocation after RTSA. By identifying risk factors for dislocation, we will be able to implement additional perioperative clinical measures to reduce the incidence of dislocation.

Materials and Methods

This retrospective study of dislocation after RTSA was conducted at the Rothman Institute of Orthopedics and Methodist Hospital (Thomas Jefferson University Hospitals, Philadelphia, PA). After obtaining Institutional Review Board approval for the study, we searched our institution’s electronic database of shoulder arthroplasties to identify all RTSAs performed at our 2 large-volume urban institutions between September 27, 2010 and December 31, 2013. For the record search, International Classification of Diseases, Ninth Revision (ICD-9) codes were used (Table 1).

These unique procedure codes are used by the hospital system for billing, but are not always specific to assigned procedures. Therefore, the individual operative reports identified were reviewed to identify the patients who actually underwent RTSA. From this database, all patients who underwent RTSA were selected. Using the subpopulation of patients who underwent RTSA, we searched individual medical records to identify patients who had a dislocation after RTSA. This information was cross-referenced with ICD-9 codes for shoulder dislocation (831.0, 831.01, 831.02, 831.03) to ensure that all patients were identified.

The medical records of each patient were used to identify independent variables that could be associated with dislocation rate. Demographic variables included sex, age, and race. Preoperative clinical data included body mass index (BMI), etiology of shoulder disease leading to RTSA, individual comorbidities, and Charlson Comorbidity Index (CCI)¹⁶ modified to be used with ICD-9 codes.¹⁷ In addition, prior shoulder surgery history and arthroplasty type (primary or revision) were determined. Postoperative considerations were time to dislocation, mechanism of dislocation, and intervention(s) needed for dislocation. Although the institutional database did not include operative variables such as prosthesis type and surgical approach, all 6 surgeons in this study were using a standard deltopectoral approach in beach-chair position with a Grammont style prosthesis for RTSA cases.

Descriptive statistics for RTSA patients and the dislocation subpopulation were compiled. Bivariate analysis was used to evaluate which of the previously described variables influenced dislocation rates. Last, multivariate logistic regression analysis was performed to evaluate which factors were independent predictors of dislocation. We included demographic variables (age, sex, ethnicity), clinical variables (BMI, individual comorbidities, CCI), and surgical variables (primary vs revision, diagnosis at time of surgery). All statistical analyses were performed with Excel 2013 (Microsoft) and SPSS Statistics Version 20.0 (SPSS Inc.).

Results

From the database, we identified 487 patients who underwent 510 RTSAs during the study period. These surgeries were performed by 6 shoulder and elbow fellowship–trained surgeons. Of the 510 RTSAs, 393 (77.1%) were primary cases, and 117 (22.9%) were revision cases.

Of the 510 shoulders that underwent RTSA, 15 (2.9%; 14 patients) dislocated. Of these 15 cases, 5 were primary (1.3% of all primary cases) and 10 were revision (8.5% of all revision cases). Mean time from index surgery to diagnosis of dislocation was 58.2 days (range, 0-319 days). One dislocation occurred immediately after surgery, 2 after falls, 4 from patient-identified low-energy mechanisms of injury, and 8 without known inciting events. Nine dislocations (60%) did not have a subscapularis repair (7 were irreparable, 2 underwent subscapularis peel without repair), and the other 6 were repaired primarily (Table 2).

In addition, 11 dislocations (73.3%) previously underwent open or arthroscopic shoulder surgery. All patients who had a dislocation after RTSA returned to the operating room at least once; no dislocation was successfully treated with closed reduction in the clinic. The 15 dislocations underwent 17 surgeries: 7 isolated polyethylene exchanges, 2 isolated closed reductions, 1 hematoma aspiration with closed reduction, 1 open reduction, 2 humeral component revisions with polyethylene exchange, 1 humeral augmentation with polyethylene exchange, 2 glenosphere exchanges with polyethylene exchange, and 1 polyethylene exchange with concurrent subscapularis repair.

Male patients accounted for 32.2% of the study population but 60.0% of the dislocations (P = .019) (Table 3).

In addition, mean BMI was 33.2 for patients with dislocation and 29.5 for patients without dislocation (P = .039) (Table 3). Revision arthroplasty was found to be a risk factor for dislocation in univariate analysis: 66.7% of the dislocations occurred after revision RTSA, and only 21.6% of nondislocated shoulders were revision cases (P < .001) (Table 4).

Patients who underwent RTSA for CTA had a very low incidence of dislocation (0.35%, 1/285), accounting for 6.7% of the dislocated group and 57.6% of the nondislocated group (P < .001) (Table 4). The 1 patient with a dislocation after primary RTSA for CTA had an indolent infection at time of surgery after dislocation.

Multivariate logistic regression analysis revealed revision arthroplasty (OR = 7.515; P = .042) and increased BMI (OR = 1.09; P = .047) to be independent risk factors for dislocation after RTSA. Analysis also found a diagnosis of primary CTA to be independently associated with lower risk of dislocation after RTSA (OR = 0.025; P = .008). Last, the previously described risk factor of male sex was found not to be a significant independent risk factor, though it did trend positively (OR = 3.011; P = .071).

 

Discussion

With more RTSAs being performed, evaluation of their common complications becomes increasingly important.¹⁸ We found a 3.0% rate of dislocation after RTSA, which is consistent with the most recently reported incidence⁴ and falls within the previously described range of 0% to 8.6%.^19-26 Of the clinical risk factors identified in this study, those previously described were prior surgery, subscapularis insufficiency, higher BMI, and male sex.⁴ However, our finding of lower risk of dislocation after RTSA for primary rotator cuff pathology was not previously described. Although Chalmers and colleagues⁴ did not report this lower risk, 3 (27.3%) of their 11 patients with dislocation had primary CTA, compared with 1 (6.7%) of 15 patients in the present study.⁴ Our literature review did not identify any studies that independently reported the dislocation rate in patients who underwent RTSA for rotator cuff failure.

The risk factors of subscapularis irreparability and revision surgery suggest the importance of the soft-tissue envelope and bony anatomy in dislocation prevention. Previous analyses have suggested implant malpositioning,^27,28 poor subscapularis quality,²⁹ and inadequate muscle tensioning^5,30-32 as risk factors for RTSA. Patients with an irreparable subscapularis tendon have often had multiple surgeries with compromise to the muscle/soft-tissue envelope or bony anatomy of the shoulder. A biomechanical study by Gutiérrez and colleagues³¹ found the compressive forces of the soft tissue at the glenohumeral joint to be the most important contributor to stability in the RTSA prosthesis. In clinical studies, the role of the subscapularis in preventing instability after RTSA remains unclear. Edwards and colleagues²⁹ prospectively compared dislocation rates in patients with reparable and irreparable subscapularis tendons during RTSA and found a higher rate of dislocation in the irreparable subscapularis group. Of note, patients in the irreparable subscapularis group also had more complex diagnoses, including proximal humeral nonunion, fixed glenohumeral dislocation, and failed prior arthroplasty. Clark and colleagues³³ retrospectively analyzed subscapularis repair in 2 RTSA groups and found no appreciable effect on complication rate, dislocation events, range-of-motion gains, or pain relief.

Our finding that higher BMI is an independent risk factor was previously described.⁴ The association is unclear but could be related to implant positioning, difficulty in intraoperative assessment of muscle tensioning, or body habitus that may generate a lever arm for impingement and dislocation when the arm is in adduction. Last, our finding that male sex is a risk factor for dislocation approached significance, and this relationship was previously reported.⁴ This could be attributable to a higher rate of activity or of indolent infection in male patients.^34,35Besides studying risk factors for dislocation after RTSA, we investigated treatment. None of our patients were treated successfully and definitively with closed reduction in the clinic. This finding diverges from findings in studies by Teusink and colleagues² and Chalmers and colleagues,⁴who respectively reported 62% and 44% rates of success with closed reduction. Our cohort of 14 patients with 15 dislocations required a total of 17 trips to the operating room after dislocation. This significantly higher rate of return to the operating room suggests that dislocation after RTSA may be a more costly and morbid problem than has been previously described.

This study had several weaknesses. Despite its large consecutive series of patients, the study was retrospective, and several variables that would be documented and controlled in a prospective study could not be measured here. Specifically, neither preoperative physical examination nor patient-specific assessments of pain or function were consistently obtained. Similarly, postoperative patient-specific instruments of outcomes evaluation were not obtained consistently, so results of patients with dislocation could not be compared with those of a control group. In addition, preoperative and postoperative radiographs were not consistently present in our electronic medical records, so the influence of preoperative bony anatomy, intraoperative limb lengthening, and any implant malpositioning could not be determined. Furthermore, operative details, such as reparability of the subscapularis, were not fully available for the control group and could not be included in statistical analysis. In addition, that the known dislocation risk factor of male sex⁴ was identified here but was not significant in multivariate regression analysis suggests that this study may not have been adequately powered to identify a significant difference in dislocation rate between the sexes. Last, though our results suggested associations between the aforementioned variables and dislocation after RTSA, a truly causative relationship could not be confirmed with this study design or analysis. Therefore, our study findings are hypothesis-generating and may indicate a benefit to greater deltoid tensioning, use of retentive liners, or more conservative rehabilitation protocols for high-risk patients.

Conclusion

Dislocation after RTSA is an uncommon complication that often requires a return to the operating room. This study identified a modifiable risk factor (higher BMI) and 3 nonmodifiable risk factors (male sex, subscapularis insufficiency, revision surgery) for dislocation after RTSA. In contrast, patients who undergo RTSA for primary rotator cuff pathology are unlikely to dislocate after surgery. This low risk of dislocation after RTSA for primary cuff pathology was not previously described. Patients in the higher risk category may benefit from preoperative lifestyle modification, intraoperative techniques for increasing stability, and more conservative therapy after surgery. In addition, unlike previous investigations, this study did not find closed reduction in the clinic alone to be successful in definitively treating this patient population.

Am J Orthop. 2016;45(7):E444-E450. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.

The rate of medical visits for rotator cuff pathology and the US incidence of arthroscopic rotator cuff repair (RCR) have increased over the past 10 years.¹ The increased use of RCR has been justified with improved patient outcomes.^2,3 Advances in surgical techniques and instrumentation have contributed to better outcomes for patients with rotator cuff pathology.^3-5 Several studies have validated RCR with functional outcome measures, cost–benefit analysis, and health-related quality-of-life measurements.^6-9

Healthcare reimbursement models are being changed to include capitated care, pay for performance, and penalties.¹⁰ Given the changing healthcare climate and the increasing incidence of RCR, it is becoming increasingly important for orthopedic surgeons to critically evaluate and modify their practice and procedures to decrease costs without compromising outcomes.¹¹ RCR outcome studies have focused on comparing open/mini-open with arthroscopic techniques, and single-row with double-row techniques, among others.^4,12-18 Furthermore, several studies on the cost-effectiveness of these surgical techniques have been conducted.^19-21Arthroscopic anchorless (transosseous [TO]) RCR, which is increasingly popular,²² combines the minimal invasiveness of arthroscopic procedures with the biomechanical strength of open TO repair. In addition, this technique avoids the potential complications and costs associated with suture anchors, such as anchor pullout and greater tuberosity osteolysis.^22,23 Several studies have documented the effectiveness of this technique.^24-26 Biomechanical and clinical outcome data supporting arthroscopic TO-RCR have been published, but there are no reports of studies that have analyzed the cost savings associated with this technique.

In this study, we compared implant costs associated with arthroscopic TO-RCR and arthroscopic TO-equivalent (TOE) RCR. We also evaluated these techniques’ operative time and outcomes. Our hypothesis was that arthroscopic TO-RCR can be performed at lower cost and without increasing operative time or compromising outcomes.

Materials and Methods

Our Institutional Review Board approved this study. Between February 2013 and January 2014, participating surgeons performed 43 arthroscopic TO-RCRs that met the study’s inclusion criteria. Twenty-one of the 43 patients enrolled and became the study group. The control group of 21 patients, who underwent arthroscopic TOE-RCR the preceding year (between January 2012 and January 2013), was matched to the study group on tear size and concomitant procedures, including biceps treatment, labral treatment, acromioplasty, and distal clavicle excision (Table 1).

Males or nonpregnant females, age 18 years or older, with full-thickness rotator cuff tear treated with arthroscopic RCR at one regional healthcare system were eligible for the study. Exclusion criteria were revision repair, irreparable tear, worker compensation claim, and subscapularis repair.

The primary outcome measure was implant cost (amount paid by institution). Cost was determined and reported by an independent third party using Cerner Surginet as the operating room documentation system and McKessen Pathways Materials Management System for item pricing.

All arthroscopic RCRs were performed by 1 of 3 orthopedic surgeons fellowship-trained in either sports medicine or shoulder and elbow surgery. Using the Cofield classification,²⁷ the treating surgeon recorded the size of the rotator cuff tear: small (<1 cm), medium (1-3 cm), large (3-5 cm), massive (>5 cm). The surgeon also recorded the number of suture anchors used, repair technique, biceps treatment, execution of subacromial decompression, execution of distal clavicle excision, and intraoperative complications. TO repair surgical technique is described in the next section. TOE repair was double-row repair with suture anchors. The number of suture anchors varied by tear size: small (3 anchors), medium (2-5 anchors), large (4-6 anchors), massive (4-5 anchors).

Secondary outcome measures were operative time (time from cut to close) and scores on pain VAS (visual analog scale), SANE (Single Assessment Numeric Evaluation), and SST (Simple Shoulder Test). Demographic information was also obtained: age, sex, body mass index, smoking status (Table 1). All patients were asked to fill out questionnaires before surgery and 3, 6, and >12 months after surgery. Outcome surveys were scored by a single research coordinator, who recorded each patient’s outcome scores at the preoperative and postoperative intervals. Follow-up of >12 months was reached by 17 (81%) of the 21 TO patients and 14 (67%) of the 21 TOE patients. For >12 months, the overall rate of follow-up was 74%.

All patients followed the same postoperative rehabilitation protocol: sling immobilization with pendulums for 6 weeks starting at 2 weeks, passive range of motion starting at 6 weeks, and active range of motion starting at 8 weeks. At 3 months, they were allowed progressive resistant exercises with a 10-pound limit, and at 4.5 months they progressed to a 20-pound limit. At 6 months, they were cleared for discharge.

 

Surgical Technique: Arthroscopic Transosseous Repair

Surgery was performed with the patient in either the beach-chair position or the lateral decubitus position, based on surgeon preference. Our technique is similar to what has been described in the past.^22,28 The glenohumeral joint is accessed through a standard posterior portal, followed by an anterior accessory portal through the rotator interval. Standard diagnostic arthroscopy is performed and intra-articular pathology addressed. Next, the scope is placed in the subacromial space through the posterior portal. A lateral subacromial portal is established and cannulated, and a bursectomy performed. The scope is then placed in a posterolateral portal for better visualization of the rotator cuff tear. The greater tuberosity is débrided with a curette to prepare the bed for repair. An ArthroTunneler (Tornier) is used to pass sutures through the greater tuberosity. For standard 2-tunnel repair, 3 sutures are placed through each tunnel. All 6 sutures are next passed (using a suture passer) through the rotator cuff. The second and fifth suture ends that are passed through the cuff are brought out through the cannula and tied together. They are then brought into the shoulder by pulling on the opposite ends and tied alongside the greater tuberosity to create a box stitch. The box stitch acts as a medial row fixation and as a rip stitch that strengthens the vertical mattress sutures against pullout. The other 4 sutures are tied in vertical mattress configuration.

Statistical Analysis

After obtaining the TO and TOE implant costs, we compared them using a generalized linear model with negative binomial distribution and an identity link function so returned parameters were in additive dollars. This comparison included evaluation of tear size and concomitant procedures. Operative times for TO and TOE were obtained and evaluated, and then compared using time-to-event analysis and the log-rank test. Outcome scores were obtained from patients at baseline and 3, 6, and >12 months after surgery and were compared using a linear mixed model that identified change in outcome scores over time, and difference in outcome scores between the TO and TOE groups.

Results

Table 1 lists patient demographics, including age, sex, body mass index, smoking status, and concomitant procedures. The TO and TOE groups had identical tear-size distributions. In addition, they had similar numbers of concomitant procedures, though our study was underpowered to confirm equivalence. Treatment techniques differed: more biceps tenodesis cases in the TO group (n = 12) than in the TOE group (n = 2) and more biceps tenotomy cases in the TOE group (n = 8) than in the TO group (n = 1).

TO implant cost was significantly lower than TOE implant cost for all tear sizes and independent of concomitant procedures (Figure 1).

Mean (SD) implant cost was $563.10 ($29.65) for the TO group and $1489.00 ($331.05) for the TOE group. With all other factors controlled, mean (SD) implant cost was $946.91 ($100.70) more expensive for the TOE group (P < .0001).

Operative time was not significantly different between the TO and TOE groups. Mean (SD) operative time was 82.38 (24.09) minutes for the TO group and 81.71 (17.27) minutes for the TOE group. With all other factors controlled, mean operative time was 5.96 minutes shorter for the TOE group, but the difference was not significant (P = .549).

There was no significant difference in preoperative pain VAS (P = .93), SANE (P = .35), or SST (P = .36) scores between the TO and TOE groups.

At all postoperative follow-ups (3, 6, and >12 months), there was significant (P < .0001) improvement in outcome scores (VAS, SANE, SST) for both groups (Table 2).

There was no significant difference in pain VAS (P = .688), SANE (P = .882), or SST (P = .272) scores (Figure 2) between the groups across all time points.

Discussion

RCR is one of the most common orthopedic surgical procedures, and its use has increased over the past decade.^9,21 This increase coincides with the emergence of new repair techniques and implants. These advancements come at a cost. Given the increasingly cost-conscious healthcare environment and its changing reimbursement models, now surgeons must evaluate the economics of their surgical procedures in an attempt to decrease costs without compromising outcomes. We hypothesized that arthroscopic TO-RCR can be performed at lower cost relative to arthroscopic TOE-RCR and without increasing operative time or compromising short-term outcomes.

Studies on the cost-effectiveness of different RCR techniques have been conducted.^19-21 Adla and colleagues¹⁹ found that open RCR was more cost-effective than arthroscopic RCR, with most of the difference attributable to disposables and suture anchors. Genuario and colleagues²¹ found that double-row RCR was not as cost-effective as single-row RCR in treating tears of any size. They attributed the difference to 2 more anchors and about 15 more minutes in the operating room.

The increased interest in healthcare costs and the understanding that a substantial part of the cost of arthroscopic RCR is attributable to implants (suture anchors, specifically) led to recent efforts to eliminate the need for anchors. Newly available instrumentation was designed to assist in arthroscopic anchorless repair constructs using the concepts of traditional TO repair.²² Although still considered to be the RCR gold standard, TO fixation has been used less often in recent years, owing to the shift from open to arthroscopic surgery.²⁴ Arthroscopic TO-RCR allows for all the benefits of arthroscopic surgery, plus the biological and mechanical benefits of traditional open or mini-open TO repair. In addition, this technique eliminates the cost of anchors. Kummer and colleagues²⁵ confirmed with biomechanical testing that arthroscopic TO repair and double-row TOE repair are similar in strength, with a trend of less tendon displacement in the TO group.

Our study results support the hypothesis that arthroscopic TO repair provides significant cost savings over tear size–matched arthroscopic TOE repair. Implant cost was substantially higher for TOE repair than for TO repair. Mean (SD) total savings of $946.91 ($100.70) (P < .0001) can be realized performing TO rather than TOE repair. In the United States, where about 250,000 RCRs are performed each year, the use of TO repair would result in an annual savings of almost $250 million.⁶Operative time was analyzed as well. Running an operating room in the United States costs an estimated $62 per minute (range, $22-$133 per minute).²⁹ Much of this cost is indirect, unrelated to the surgery (eg, capital investment, personnel, insurance), and is being paid even when the operating room is not in use. Therefore, for the hospital’s bottom line, operative time savings are less important than direct cost savings (supplies, implants). However, operative time has more of an effect on the surgeon’s bottom line, and longer procedures reduce the number of surgeries that can be performed and billed. We found no significant difference in operative time between TO and TOE repairs. Critical evaluation revealed that operative time was 5.96 minutes shorter for TOE repairs, but this difference was not significant (P = .677).

Our study results showed no significant difference in clinical outcomes between TO and TOE repair patients. Both groups’ outcome scores improved. At all follow-ups, both groups’ VAS, SANE, and SST scores were significantly improved. Overall, this is the first study to validate the proposed cost benefit of arthroscopic TO repair and confirm no compromise in patient outcomes.

This study had limitations. First, it enrolled relatively few patients, particularly those with small tears. In addition, despite the fact that patients were matched on tear size and concomitant procedures, the groups differed in their biceps pathology treatments. Of the 13 TO patients who had biceps treatment, 12 underwent tenodesis (1 had tenotomy); in contrast, of the 10 TOE patients who had biceps treatment, only 2 underwent tenodesis (8 had tenotomy). The difference is explained by the consecutive course of this study and the increasing popularity of tenodesis over tenotomy. The TOE group underwent surgery before the TO group did, at a time when the involved surgeons were routinely performing tenotomy more than tenodesis. We did not include the costs of implants related to biceps treatment in our analysis, as our focus was on the implant cost of RCR. As for operative time, biceps tenodesis would be expected to extend surgery and potentially affect the comparison of operative times between the TO and TOE groups. However, despite the fact that 12 of the 13 TO patients underwent biceps tenodesis, there was no significant difference in overall operative time. Last, regarding the effect of biceps treatment on clinical outcomes, there are no data showing improved outcomes with tenodesis over tenotomy in the setting of RCR.

A final limitation is lack of data from longer term (>12 months) follow-up for all patients. Our analysis included cost and operative time data for all 42 enrolled patients, but our clinical outcome data represent only 74% of the patients enrolled. Eleven of the 42 patients were lost to follow-up at >12 months, and outcome scores could not be obtained, despite multiple attempts at contact (phone, mail, email). The study design and primary outcome variable focused on cost analysis rather than clinical outcomes. Nevertheless, our data support our hypothesis that there is no difference in clinical outcomes between TO and TOE repairs.

 

Conclusion

Arthroscopic TO-RCR provides significant cost savings over arthroscopic TOE-RCR without increasing operative time or compromising outcomes. Arthroscopic TO-RCR may have an important role in the evolving healthcare environment and its changing reimbursement models.

Am J Orthop. 2016;45(7):E415-E420. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.

The rate of medical visits for rotator cuff pathology and the US incidence of arthroscopic rotator cuff repair (RCR) have increased over the past 10 years.¹ The increased use of RCR has been justified with improved patient outcomes.^2,3 Advances in surgical techniques and instrumentation have contributed to better outcomes for patients with rotator cuff pathology.^3-5 Several studies have validated RCR with functional outcome measures, cost–benefit analysis, and health-related quality-of-life measurements.^6-9

Healthcare reimbursement models are being changed to include capitated care, pay for performance, and penalties.¹⁰ Given the changing healthcare climate and the increasing incidence of RCR, it is becoming increasingly important for orthopedic surgeons to critically evaluate and modify their practice and procedures to decrease costs without compromising outcomes.¹¹ RCR outcome studies have focused on comparing open/mini-open with arthroscopic techniques, and single-row with double-row techniques, among others.^4,12-18 Furthermore, several studies on the cost-effectiveness of these surgical techniques have been conducted.^19-21Arthroscopic anchorless (transosseous [TO]) RCR, which is increasingly popular,²² combines the minimal invasiveness of arthroscopic procedures with the biomechanical strength of open TO repair. In addition, this technique avoids the potential complications and costs associated with suture anchors, such as anchor pullout and greater tuberosity osteolysis.^22,23 Several studies have documented the effectiveness of this technique.^24-26 Biomechanical and clinical outcome data supporting arthroscopic TO-RCR have been published, but there are no reports of studies that have analyzed the cost savings associated with this technique.

In this study, we compared implant costs associated with arthroscopic TO-RCR and arthroscopic TO-equivalent (TOE) RCR. We also evaluated these techniques’ operative time and outcomes. Our hypothesis was that arthroscopic TO-RCR can be performed at lower cost and without increasing operative time or compromising outcomes.

Materials and Methods

Our Institutional Review Board approved this study. Between February 2013 and January 2014, participating surgeons performed 43 arthroscopic TO-RCRs that met the study’s inclusion criteria. Twenty-one of the 43 patients enrolled and became the study group. The control group of 21 patients, who underwent arthroscopic TOE-RCR the preceding year (between January 2012 and January 2013), was matched to the study group on tear size and concomitant procedures, including biceps treatment, labral treatment, acromioplasty, and distal clavicle excision (Table 1).

Males or nonpregnant females, age 18 years or older, with full-thickness rotator cuff tear treated with arthroscopic RCR at one regional healthcare system were eligible for the study. Exclusion criteria were revision repair, irreparable tear, worker compensation claim, and subscapularis repair.

The primary outcome measure was implant cost (amount paid by institution). Cost was determined and reported by an independent third party using Cerner Surginet as the operating room documentation system and McKessen Pathways Materials Management System for item pricing.

All arthroscopic RCRs were performed by 1 of 3 orthopedic surgeons fellowship-trained in either sports medicine or shoulder and elbow surgery. Using the Cofield classification,²⁷ the treating surgeon recorded the size of the rotator cuff tear: small (<1 cm), medium (1-3 cm), large (3-5 cm), massive (>5 cm). The surgeon also recorded the number of suture anchors used, repair technique, biceps treatment, execution of subacromial decompression, execution of distal clavicle excision, and intraoperative complications. TO repair surgical technique is described in the next section. TOE repair was double-row repair with suture anchors. The number of suture anchors varied by tear size: small (3 anchors), medium (2-5 anchors), large (4-6 anchors), massive (4-5 anchors).

Secondary outcome measures were operative time (time from cut to close) and scores on pain VAS (visual analog scale), SANE (Single Assessment Numeric Evaluation), and SST (Simple Shoulder Test). Demographic information was also obtained: age, sex, body mass index, smoking status (Table 1). All patients were asked to fill out questionnaires before surgery and 3, 6, and >12 months after surgery. Outcome surveys were scored by a single research coordinator, who recorded each patient’s outcome scores at the preoperative and postoperative intervals. Follow-up of >12 months was reached by 17 (81%) of the 21 TO patients and 14 (67%) of the 21 TOE patients. For >12 months, the overall rate of follow-up was 74%.

All patients followed the same postoperative rehabilitation protocol: sling immobilization with pendulums for 6 weeks starting at 2 weeks, passive range of motion starting at 6 weeks, and active range of motion starting at 8 weeks. At 3 months, they were allowed progressive resistant exercises with a 10-pound limit, and at 4.5 months they progressed to a 20-pound limit. At 6 months, they were cleared for discharge.

 

Surgical Technique: Arthroscopic Transosseous Repair

Surgery was performed with the patient in either the beach-chair position or the lateral decubitus position, based on surgeon preference. Our technique is similar to what has been described in the past.^22,28 The glenohumeral joint is accessed through a standard posterior portal, followed by an anterior accessory portal through the rotator interval. Standard diagnostic arthroscopy is performed and intra-articular pathology addressed. Next, the scope is placed in the subacromial space through the posterior portal. A lateral subacromial portal is established and cannulated, and a bursectomy performed. The scope is then placed in a posterolateral portal for better visualization of the rotator cuff tear. The greater tuberosity is débrided with a curette to prepare the bed for repair. An ArthroTunneler (Tornier) is used to pass sutures through the greater tuberosity. For standard 2-tunnel repair, 3 sutures are placed through each tunnel. All 6 sutures are next passed (using a suture passer) through the rotator cuff. The second and fifth suture ends that are passed through the cuff are brought out through the cannula and tied together. They are then brought into the shoulder by pulling on the opposite ends and tied alongside the greater tuberosity to create a box stitch. The box stitch acts as a medial row fixation and as a rip stitch that strengthens the vertical mattress sutures against pullout. The other 4 sutures are tied in vertical mattress configuration.

Statistical Analysis

After obtaining the TO and TOE implant costs, we compared them using a generalized linear model with negative binomial distribution and an identity link function so returned parameters were in additive dollars. This comparison included evaluation of tear size and concomitant procedures. Operative times for TO and TOE were obtained and evaluated, and then compared using time-to-event analysis and the log-rank test. Outcome scores were obtained from patients at baseline and 3, 6, and >12 months after surgery and were compared using a linear mixed model that identified change in outcome scores over time, and difference in outcome scores between the TO and TOE groups.

Results

Table 1 lists patient demographics, including age, sex, body mass index, smoking status, and concomitant procedures. The TO and TOE groups had identical tear-size distributions. In addition, they had similar numbers of concomitant procedures, though our study was underpowered to confirm equivalence. Treatment techniques differed: more biceps tenodesis cases in the TO group (n = 12) than in the TOE group (n = 2) and more biceps tenotomy cases in the TOE group (n = 8) than in the TO group (n = 1).

TO implant cost was significantly lower than TOE implant cost for all tear sizes and independent of concomitant procedures (Figure 1).

Mean (SD) implant cost was $563.10 ($29.65) for the TO group and $1489.00 ($331.05) for the TOE group. With all other factors controlled, mean (SD) implant cost was $946.91 ($100.70) more expensive for the TOE group (P < .0001).

Operative time was not significantly different between the TO and TOE groups. Mean (SD) operative time was 82.38 (24.09) minutes for the TO group and 81.71 (17.27) minutes for the TOE group. With all other factors controlled, mean operative time was 5.96 minutes shorter for the TOE group, but the difference was not significant (P = .549).

There was no significant difference in preoperative pain VAS (P = .93), SANE (P = .35), or SST (P = .36) scores between the TO and TOE groups.

At all postoperative follow-ups (3, 6, and >12 months), there was significant (P < .0001) improvement in outcome scores (VAS, SANE, SST) for both groups (Table 2).

There was no significant difference in pain VAS (P = .688), SANE (P = .882), or SST (P = .272) scores (Figure 2) between the groups across all time points.

Discussion

RCR is one of the most common orthopedic surgical procedures, and its use has increased over the past decade.^9,21 This increase coincides with the emergence of new repair techniques and implants. These advancements come at a cost. Given the increasingly cost-conscious healthcare environment and its changing reimbursement models, now surgeons must evaluate the economics of their surgical procedures in an attempt to decrease costs without compromising outcomes. We hypothesized that arthroscopic TO-RCR can be performed at lower cost relative to arthroscopic TOE-RCR and without increasing operative time or compromising short-term outcomes.

Studies on the cost-effectiveness of different RCR techniques have been conducted.^19-21 Adla and colleagues¹⁹ found that open RCR was more cost-effective than arthroscopic RCR, with most of the difference attributable to disposables and suture anchors. Genuario and colleagues²¹ found that double-row RCR was not as cost-effective as single-row RCR in treating tears of any size. They attributed the difference to 2 more anchors and about 15 more minutes in the operating room.

The increased interest in healthcare costs and the understanding that a substantial part of the cost of arthroscopic RCR is attributable to implants (suture anchors, specifically) led to recent efforts to eliminate the need for anchors. Newly available instrumentation was designed to assist in arthroscopic anchorless repair constructs using the concepts of traditional TO repair.²² Although still considered to be the RCR gold standard, TO fixation has been used less often in recent years, owing to the shift from open to arthroscopic surgery.²⁴ Arthroscopic TO-RCR allows for all the benefits of arthroscopic surgery, plus the biological and mechanical benefits of traditional open or mini-open TO repair. In addition, this technique eliminates the cost of anchors. Kummer and colleagues²⁵ confirmed with biomechanical testing that arthroscopic TO repair and double-row TOE repair are similar in strength, with a trend of less tendon displacement in the TO group.

Our study results support the hypothesis that arthroscopic TO repair provides significant cost savings over tear size–matched arthroscopic TOE repair. Implant cost was substantially higher for TOE repair than for TO repair. Mean (SD) total savings of $946.91 ($100.70) (P < .0001) can be realized performing TO rather than TOE repair. In the United States, where about 250,000 RCRs are performed each year, the use of TO repair would result in an annual savings of almost $250 million.⁶Operative time was analyzed as well. Running an operating room in the United States costs an estimated $62 per minute (range, $22-$133 per minute).²⁹ Much of this cost is indirect, unrelated to the surgery (eg, capital investment, personnel, insurance), and is being paid even when the operating room is not in use. Therefore, for the hospital’s bottom line, operative time savings are less important than direct cost savings (supplies, implants). However, operative time has more of an effect on the surgeon’s bottom line, and longer procedures reduce the number of surgeries that can be performed and billed. We found no significant difference in operative time between TO and TOE repairs. Critical evaluation revealed that operative time was 5.96 minutes shorter for TOE repairs, but this difference was not significant (P = .677).

Our study results showed no significant difference in clinical outcomes between TO and TOE repair patients. Both groups’ outcome scores improved. At all follow-ups, both groups’ VAS, SANE, and SST scores were significantly improved. Overall, this is the first study to validate the proposed cost benefit of arthroscopic TO repair and confirm no compromise in patient outcomes.

This study had limitations. First, it enrolled relatively few patients, particularly those with small tears. In addition, despite the fact that patients were matched on tear size and concomitant procedures, the groups differed in their biceps pathology treatments. Of the 13 TO patients who had biceps treatment, 12 underwent tenodesis (1 had tenotomy); in contrast, of the 10 TOE patients who had biceps treatment, only 2 underwent tenodesis (8 had tenotomy). The difference is explained by the consecutive course of this study and the increasing popularity of tenodesis over tenotomy. The TOE group underwent surgery before the TO group did, at a time when the involved surgeons were routinely performing tenotomy more than tenodesis. We did not include the costs of implants related to biceps treatment in our analysis, as our focus was on the implant cost of RCR. As for operative time, biceps tenodesis would be expected to extend surgery and potentially affect the comparison of operative times between the TO and TOE groups. However, despite the fact that 12 of the 13 TO patients underwent biceps tenodesis, there was no significant difference in overall operative time. Last, regarding the effect of biceps treatment on clinical outcomes, there are no data showing improved outcomes with tenodesis over tenotomy in the setting of RCR.

A final limitation is lack of data from longer term (>12 months) follow-up for all patients. Our analysis included cost and operative time data for all 42 enrolled patients, but our clinical outcome data represent only 74% of the patients enrolled. Eleven of the 42 patients were lost to follow-up at >12 months, and outcome scores could not be obtained, despite multiple attempts at contact (phone, mail, email). The study design and primary outcome variable focused on cost analysis rather than clinical outcomes. Nevertheless, our data support our hypothesis that there is no difference in clinical outcomes between TO and TOE repairs.

 

Conclusion

Arthroscopic TO-RCR provides significant cost savings over arthroscopic TOE-RCR without increasing operative time or compromising outcomes. Arthroscopic TO-RCR may have an important role in the evolving healthcare environment and its changing reimbursement models.

Am J Orthop. 2016;45(7):E415-E420. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.

The rate of medical visits for rotator cuff pathology and the US incidence of arthroscopic rotator cuff repair (RCR) have increased over the past 10 years.¹ The increased use of RCR has been justified with improved patient outcomes.^2,3 Advances in surgical techniques and instrumentation have contributed to better outcomes for patients with rotator cuff pathology.^3-5 Several studies have validated RCR with functional outcome measures, cost–benefit analysis, and health-related quality-of-life measurements.^6-9

Healthcare reimbursement models are being changed to include capitated care, pay for performance, and penalties.¹⁰ Given the changing healthcare climate and the increasing incidence of RCR, it is becoming increasingly important for orthopedic surgeons to critically evaluate and modify their practice and procedures to decrease costs without compromising outcomes.¹¹ RCR outcome studies have focused on comparing open/mini-open with arthroscopic techniques, and single-row with double-row techniques, among others.^4,12-18 Furthermore, several studies on the cost-effectiveness of these surgical techniques have been conducted.^19-21Arthroscopic anchorless (transosseous [TO]) RCR, which is increasingly popular,²² combines the minimal invasiveness of arthroscopic procedures with the biomechanical strength of open TO repair. In addition, this technique avoids the potential complications and costs associated with suture anchors, such as anchor pullout and greater tuberosity osteolysis.^22,23 Several studies have documented the effectiveness of this technique.^24-26 Biomechanical and clinical outcome data supporting arthroscopic TO-RCR have been published, but there are no reports of studies that have analyzed the cost savings associated with this technique.

In this study, we compared implant costs associated with arthroscopic TO-RCR and arthroscopic TO-equivalent (TOE) RCR. We also evaluated these techniques’ operative time and outcomes. Our hypothesis was that arthroscopic TO-RCR can be performed at lower cost and without increasing operative time or compromising outcomes.

Materials and Methods

Our Institutional Review Board approved this study. Between February 2013 and January 2014, participating surgeons performed 43 arthroscopic TO-RCRs that met the study’s inclusion criteria. Twenty-one of the 43 patients enrolled and became the study group. The control group of 21 patients, who underwent arthroscopic TOE-RCR the preceding year (between January 2012 and January 2013), was matched to the study group on tear size and concomitant procedures, including biceps treatment, labral treatment, acromioplasty, and distal clavicle excision (Table 1).

Males or nonpregnant females, age 18 years or older, with full-thickness rotator cuff tear treated with arthroscopic RCR at one regional healthcare system were eligible for the study. Exclusion criteria were revision repair, irreparable tear, worker compensation claim, and subscapularis repair.

The primary outcome measure was implant cost (amount paid by institution). Cost was determined and reported by an independent third party using Cerner Surginet as the operating room documentation system and McKessen Pathways Materials Management System for item pricing.

All arthroscopic RCRs were performed by 1 of 3 orthopedic surgeons fellowship-trained in either sports medicine or shoulder and elbow surgery. Using the Cofield classification,²⁷ the treating surgeon recorded the size of the rotator cuff tear: small (<1 cm), medium (1-3 cm), large (3-5 cm), massive (>5 cm). The surgeon also recorded the number of suture anchors used, repair technique, biceps treatment, execution of subacromial decompression, execution of distal clavicle excision, and intraoperative complications. TO repair surgical technique is described in the next section. TOE repair was double-row repair with suture anchors. The number of suture anchors varied by tear size: small (3 anchors), medium (2-5 anchors), large (4-6 anchors), massive (4-5 anchors).

Secondary outcome measures were operative time (time from cut to close) and scores on pain VAS (visual analog scale), SANE (Single Assessment Numeric Evaluation), and SST (Simple Shoulder Test). Demographic information was also obtained: age, sex, body mass index, smoking status (Table 1). All patients were asked to fill out questionnaires before surgery and 3, 6, and >12 months after surgery. Outcome surveys were scored by a single research coordinator, who recorded each patient’s outcome scores at the preoperative and postoperative intervals. Follow-up of >12 months was reached by 17 (81%) of the 21 TO patients and 14 (67%) of the 21 TOE patients. For >12 months, the overall rate of follow-up was 74%.

All patients followed the same postoperative rehabilitation protocol: sling immobilization with pendulums for 6 weeks starting at 2 weeks, passive range of motion starting at 6 weeks, and active range of motion starting at 8 weeks. At 3 months, they were allowed progressive resistant exercises with a 10-pound limit, and at 4.5 months they progressed to a 20-pound limit. At 6 months, they were cleared for discharge.

 

Surgical Technique: Arthroscopic Transosseous Repair

Surgery was performed with the patient in either the beach-chair position or the lateral decubitus position, based on surgeon preference. Our technique is similar to what has been described in the past.^22,28 The glenohumeral joint is accessed through a standard posterior portal, followed by an anterior accessory portal through the rotator interval. Standard diagnostic arthroscopy is performed and intra-articular pathology addressed. Next, the scope is placed in the subacromial space through the posterior portal. A lateral subacromial portal is established and cannulated, and a bursectomy performed. The scope is then placed in a posterolateral portal for better visualization of the rotator cuff tear. The greater tuberosity is débrided with a curette to prepare the bed for repair. An ArthroTunneler (Tornier) is used to pass sutures through the greater tuberosity. For standard 2-tunnel repair, 3 sutures are placed through each tunnel. All 6 sutures are next passed (using a suture passer) through the rotator cuff. The second and fifth suture ends that are passed through the cuff are brought out through the cannula and tied together. They are then brought into the shoulder by pulling on the opposite ends and tied alongside the greater tuberosity to create a box stitch. The box stitch acts as a medial row fixation and as a rip stitch that strengthens the vertical mattress sutures against pullout. The other 4 sutures are tied in vertical mattress configuration.

Statistical Analysis

After obtaining the TO and TOE implant costs, we compared them using a generalized linear model with negative binomial distribution and an identity link function so returned parameters were in additive dollars. This comparison included evaluation of tear size and concomitant procedures. Operative times for TO and TOE were obtained and evaluated, and then compared using time-to-event analysis and the log-rank test. Outcome scores were obtained from patients at baseline and 3, 6, and >12 months after surgery and were compared using a linear mixed model that identified change in outcome scores over time, and difference in outcome scores between the TO and TOE groups.

Results

Table 1 lists patient demographics, including age, sex, body mass index, smoking status, and concomitant procedures. The TO and TOE groups had identical tear-size distributions. In addition, they had similar numbers of concomitant procedures, though our study was underpowered to confirm equivalence. Treatment techniques differed: more biceps tenodesis cases in the TO group (n = 12) than in the TOE group (n = 2) and more biceps tenotomy cases in the TOE group (n = 8) than in the TO group (n = 1).

TO implant cost was significantly lower than TOE implant cost for all tear sizes and independent of concomitant procedures (Figure 1).

Mean (SD) implant cost was $563.10 ($29.65) for the TO group and $1489.00 ($331.05) for the TOE group. With all other factors controlled, mean (SD) implant cost was $946.91 ($100.70) more expensive for the TOE group (P < .0001).

Operative time was not significantly different between the TO and TOE groups. Mean (SD) operative time was 82.38 (24.09) minutes for the TO group and 81.71 (17.27) minutes for the TOE group. With all other factors controlled, mean operative time was 5.96 minutes shorter for the TOE group, but the difference was not significant (P = .549).

There was no significant difference in preoperative pain VAS (P = .93), SANE (P = .35), or SST (P = .36) scores between the TO and TOE groups.

At all postoperative follow-ups (3, 6, and >12 months), there was significant (P < .0001) improvement in outcome scores (VAS, SANE, SST) for both groups (Table 2).

There was no significant difference in pain VAS (P = .688), SANE (P = .882), or SST (P = .272) scores (Figure 2) between the groups across all time points.

Discussion

RCR is one of the most common orthopedic surgical procedures, and its use has increased over the past decade.^9,21 This increase coincides with the emergence of new repair techniques and implants. These advancements come at a cost. Given the increasingly cost-conscious healthcare environment and its changing reimbursement models, now surgeons must evaluate the economics of their surgical procedures in an attempt to decrease costs without compromising outcomes. We hypothesized that arthroscopic TO-RCR can be performed at lower cost relative to arthroscopic TOE-RCR and without increasing operative time or compromising short-term outcomes.

Studies on the cost-effectiveness of different RCR techniques have been conducted.^19-21 Adla and colleagues¹⁹ found that open RCR was more cost-effective than arthroscopic RCR, with most of the difference attributable to disposables and suture anchors. Genuario and colleagues²¹ found that double-row RCR was not as cost-effective as single-row RCR in treating tears of any size. They attributed the difference to 2 more anchors and about 15 more minutes in the operating room.

The increased interest in healthcare costs and the understanding that a substantial part of the cost of arthroscopic RCR is attributable to implants (suture anchors, specifically) led to recent efforts to eliminate the need for anchors. Newly available instrumentation was designed to assist in arthroscopic anchorless repair constructs using the concepts of traditional TO repair.²² Although still considered to be the RCR gold standard, TO fixation has been used less often in recent years, owing to the shift from open to arthroscopic surgery.²⁴ Arthroscopic TO-RCR allows for all the benefits of arthroscopic surgery, plus the biological and mechanical benefits of traditional open or mini-open TO repair. In addition, this technique eliminates the cost of anchors. Kummer and colleagues²⁵ confirmed with biomechanical testing that arthroscopic TO repair and double-row TOE repair are similar in strength, with a trend of less tendon displacement in the TO group.

Our study results support the hypothesis that arthroscopic TO repair provides significant cost savings over tear size–matched arthroscopic TOE repair. Implant cost was substantially higher for TOE repair than for TO repair. Mean (SD) total savings of $946.91 ($100.70) (P < .0001) can be realized performing TO rather than TOE repair. In the United States, where about 250,000 RCRs are performed each year, the use of TO repair would result in an annual savings of almost $250 million.⁶Operative time was analyzed as well. Running an operating room in the United States costs an estimated $62 per minute (range, $22-$133 per minute).²⁹ Much of this cost is indirect, unrelated to the surgery (eg, capital investment, personnel, insurance), and is being paid even when the operating room is not in use. Therefore, for the hospital’s bottom line, operative time savings are less important than direct cost savings (supplies, implants). However, operative time has more of an effect on the surgeon’s bottom line, and longer procedures reduce the number of surgeries that can be performed and billed. We found no significant difference in operative time between TO and TOE repairs. Critical evaluation revealed that operative time was 5.96 minutes shorter for TOE repairs, but this difference was not significant (P = .677).

Our study results showed no significant difference in clinical outcomes between TO and TOE repair patients. Both groups’ outcome scores improved. At all follow-ups, both groups’ VAS, SANE, and SST scores were significantly improved. Overall, this is the first study to validate the proposed cost benefit of arthroscopic TO repair and confirm no compromise in patient outcomes.

This study had limitations. First, it enrolled relatively few patients, particularly those with small tears. In addition, despite the fact that patients were matched on tear size and concomitant procedures, the groups differed in their biceps pathology treatments. Of the 13 TO patients who had biceps treatment, 12 underwent tenodesis (1 had tenotomy); in contrast, of the 10 TOE patients who had biceps treatment, only 2 underwent tenodesis (8 had tenotomy). The difference is explained by the consecutive course of this study and the increasing popularity of tenodesis over tenotomy. The TOE group underwent surgery before the TO group did, at a time when the involved surgeons were routinely performing tenotomy more than tenodesis. We did not include the costs of implants related to biceps treatment in our analysis, as our focus was on the implant cost of RCR. As for operative time, biceps tenodesis would be expected to extend surgery and potentially affect the comparison of operative times between the TO and TOE groups. However, despite the fact that 12 of the 13 TO patients underwent biceps tenodesis, there was no significant difference in overall operative time. Last, regarding the effect of biceps treatment on clinical outcomes, there are no data showing improved outcomes with tenodesis over tenotomy in the setting of RCR.

A final limitation is lack of data from longer term (>12 months) follow-up for all patients. Our analysis included cost and operative time data for all 42 enrolled patients, but our clinical outcome data represent only 74% of the patients enrolled. Eleven of the 42 patients were lost to follow-up at >12 months, and outcome scores could not be obtained, despite multiple attempts at contact (phone, mail, email). The study design and primary outcome variable focused on cost analysis rather than clinical outcomes. Nevertheless, our data support our hypothesis that there is no difference in clinical outcomes between TO and TOE repairs.

 

Conclusion

Arthroscopic TO-RCR provides significant cost savings over arthroscopic TOE-RCR without increasing operative time or compromising outcomes. Arthroscopic TO-RCR may have an important role in the evolving healthcare environment and its changing reimbursement models.

Am J Orthop. 2016;45(7):E415-E420. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.

The annual number of total shoulder arthroplasties (TSAs) is rising with the growing elderly population and development of new technologies such as reverse shoulder arthroplasty.¹ In 2008, 47,000 shoulder arthroplasties were performed in the US compared with 19,000 in 1998.¹ As of 2011, there were 53,000 shoulder arthroplasties performed annually.² Pain control after shoulder procedures, particularly TSA, is challenging. ³

Several modalities exist to manage pain after shoulder arthroplasty. The interscalene brachial plexus nerve block is considered the “gold standard” for shoulder analgesia. A new approach is the periarticular injection method, in which the surgeon administers a local anesthetic intraoperatively. Liposomal bupivacaine (Exparel, Pacira Pharmaceuticals, Inc.) is a nonopioid anesthetic that has been shown to improve pain control, shorten hospital stays, and decrease costs for total knee and hip arthroplasty compared with nerve blocks.^4-6 Patients who were treated with liposomal bupivacaine consumed less opioid medication than a placebo group.⁷

Our purpose was to compare intraoperative local liposomal bupivacaine injection with preoperative single-shot interscalene nerve block (ISNB) in terms of pain control, opioid use, and length of hospital stay (LOS) after shoulder arthroplasty. We hypothesized that patients in the liposomal bupivacaine group would have lower pain scores, less opioid use, and shorter LOS compared with patients in the ISNB group.

Methods

A retrospective cohort analysis was conducted with 58 patients who underwent shoulder arthroplasty by 1 surgeon at our academically affiliated community hospital from January 2012 through January 2015. ISNBs were the standard at the beginning of the study period and were used until Exparel became available on the hospital formulary in 2013. We began using Exparel for all shoulder arthroplasties in November 2013. No other changes were made in the perioperative management of our arthroplasty patients during this period. Patients who underwent TSA, reverse TSA, or hemiarthroplasty of the shoulder were included. Patients who underwent revision TSA were excluded. Twenty-one patients received ISNBs and 37 received liposomal bupivacaine injections. This study was approved by our Institutional Review Board.

Baseline data for each patient were age, sex, body mass index, and the American Society of Anesthesiologists (ASA) Physical Status Classification. The primary outcome measure was the numeric rating scale (NRS) pain score at 4 post-operative time intervals. The NRS pain score has a range of 0 to 10, with 10 representing severe pain. Data were gathered from nursing and physical therapy notes in patient charts. The postoperative time intervals were 0 to 1 hour, 8 to 14 hours, 18 to 24 hours, and 27 to 36 hours. Available NRS scores for these time intervals were averaged. Patients were included if they had pain scores for at least 3 of the postoperative time intervals documented in their charts. Secondary outcome measures were LOS and opioid consumption during hospital admission. Intravenous acetaminophen use was also measured in both groups. All data on opioids were converted to oral morphine equivalents using the method described by Schneider and colleagues.⁸

A board-certified, fellowship-trained anesthesiologist, experienced in regional anesthesia, administered the single-shot ISNB before surgery. The block was administered under ultrasound guidance using a 44-mm, 22-gauge needle with the patient in the supine position. No indwelling catheter was used. The medication consisted of 30 mL of 5% ropivacaine (5 mg/mL). The surgeon injected liposomal bupivacaine (266 mg diluted into 40 mL of injectable saline) near the end of the procedure throughout the pericapsular area and multiple layers of the wound, per manufacturer guidelines.⁹ A 60-mL syringe with a 20-gauge needle was used. All operations were performed by 1 board-certified, fellowship-trained surgeon using a standard deltopectoral approach with the same surgical equipment. The same postoperative pain protocol was used for all patients, including intravenous acetaminophen and patient-controlled analgesia. Additional oral pain medication was provided as needed for all patients. Physical therapy protocols were identical between groups.

Statistical Analysis

Mean patient ages in the 2 treatment groups were compared using the Student t test. Sex distribution and the ASA scores were compared using a χ² test and a Fisher exact test, respectively. Arthroplasty types were compared using a Fisher exact test. The medians and interquartile ranges of the NRS scores at each time point measured were tabulated by treatment group, and at each time point the difference between groups was tested using nonparametric rank sum tests.

We tested the longitudinal trajectory of NRS scores over time, accounting for repeated measurements in the same patients using linear mixed model analysis. Treatment group, time period as a categorical variable, and the interaction between treatment and time period were included as fixed effects, and patient identification number was included as the random effect. An initial omnibus test was performed for all treatment and treatment-by-time interaction effects. Subsequently, the treatment-by-time interaction was tested for each of the time periods. The association of day of discharge (as a categorical variable) with treatment was tested using the Fisher exact test. All analyses were conducted using Stata, version 13, software (StataCorp LP). P values <.05 were considered significant.

 

Sample Size Analysis

We calculated the minimum detectable effect size with 80% power at an alpha level of 0.05 for the nonparametric rank sum test in terms of the proportion of every possible pair of patients treated with the 2 treatments, where the patient treated with liposomal bupivacaine has a lower pain score than the patient treated with ISNB. For pain score at 18 to 24 hours, the sample sizes of 33 patients treated with liposomal bupivacaine and 20 treated with ISNB, the minimum detectable effect size is 73%.

Results

Fifty-eight patient charts (21 in the ISNB group and 37 in the liposomal bupivacaine group) were reviewed for the study. Patient sex distribution, mean age, mean body mass index, and mean baseline ASA scores were not statistically different (Table 1).

In the ISNB group, 5 patients had hemiarthroplasty, 12 had TSA, and 4 had reverse TSA. In the liposomal bupivacaine group, 1 patient had hemiarthroplasty, 23 had TSA, and 13 had reverse TSA. Frequency of procedure types was significantly different between groups (P = .039), with the liposomal bupivacaine group undergoing fewer hemiarthroplasties.

The primary outcome measure, NRS pain score, showed no significant differences between groups at 0 to 1 hour after surgery (P = .99) or 8 to 14 hours after surgery (P = .208).

At 18 to 24 hours after surgery, the liposomal bupivacaine group had a lower mean NRS score than the ISNB group (P = .001). This was statistically significant when taking repeated measures of variance into account (Figure 1). Mean NRS score was also lower for the liposomal bupivacaine group at 27 to 36 hours after surgery (P = .029).

This was a significant difference when repeated measures of variance was considered (Table 2).

There was no difference in the amount of intravenous acetaminophen given during the hospital stay between groups. There was no significant difference in opioid consumption on postoperative day 1 in the hospital (P = .59) (Figure 2). However, there were significant differences between groups on postoperative days 2 and 3.

On postoperative day 2, the ISNB group required significantly more opioids (mean, 112 mg morphine equivalents) than the liposomal bupivacaine group (mean, 37 mg morphine equivalents) (P = .001). The ISNB group also required significantly more opioids (mean, 25 mg morphine equivalents) on postoperative day 3 than the liposomal bupivacaine group (mean, 5 mg) (P = .002).

Sixteen of 37 patients in the liposomal bupivacaine group and 2 of 21 in the ISNB group were discharged on the day after surgery (P = .010) (Table 3).

The mean LOS was 46 ± 20 hours for the liposomal bupivacaine group and 57 ± 14 hours for the ISNB group (P = .012).

There were no major cardiac or respiratory events in either group. No long-term paresthesias or neuropathies were noted. There were no readmissions for either group.

Discussion

Postoperative pain control after shoulder arthroplasty can be challenging, and several modalities have been tried in various combinations to minimize pain and decrease adverse effects of opioid medications. The most common method for pain relief after shoulder arthroplasty is the ISNB. Several studies of ISNBs have shown improved pain control after shoulder arthroplasty with associated decreased opioid consumption and related side effects.¹⁰ Patient rehabilitation and satisfaction have improved with the increasing use of peripheral nerve blocks.¹¹

Despite the well-established benefits of ISNBs, several limitations exist. Although the superior portion of the shoulder is well covered by an ISNB, the inferior portion of the brachial plexus can remain uncovered or only partially covered.¹² Complications of ISNBs include hemidiaphragmatic paresis, rebound pain 24 hours after surgery,¹³ chronic neurologic complications,¹⁴ and substantial respiratory and cardiovascular events.¹⁵ Nerve blocks also require additional time and resources in the perioperative period, including an anesthesiologist with specialized training, assistants, and ultrasonography or nerve stimulation equipment contraindicated in patients taking blood thinners.¹⁶

Periarticular injections of local anesthetics have also shown promise in reducing pain after arthroplasty.⁴ Benefits include an enhanced safety profile because local injection avoids the concurrent blockade of the phrenic nerve and recurrent laryngeal nerve and has not been associated with the risk of peripheral neuropathies. Further, local injection is a simple technique that can be performed during surgery without additional personnel or expertise. A limitation of this approach is the relatively short duration of effectiveness of the local anesthetic and uncertainty regarding the best agent and the ideal volume of injection.⁶ Liposomal bupivacaine is a new agent (approved by the US Food and Drug Administration in 2011¹⁷) with a sustained release over 72 to 96 hours.¹⁸ The most common adverse effects of liposomal bupivacaine are nausea, vomiting, constipation, pyrexia, dizziness, and headache.¹⁹ Chondrotoxicity and granulomatous inflammation are more serious, yet rare, complications of liposomal bupivacaine.²⁰

We found that liposomal bupivacaine injections were associated with lower pain scores compared with ISNB at 18 to 24 hours after surgery. This correlated with less opioid consumption in the liposomal bupivacaine group than in the ISNB group on the second postoperative day. These differences in pain values are consistent with the known pharmacokinetics of liposomal bupivacaine.¹⁸ Peak plasma levels normally occur approximately 24 hours after injection, leaving the early postoperative period relatively uncovered by anesthetic agent. This finding of relatively poor pain control early after surgery has also been noted in patients undergoing knee arthroplasty.⁵ On the basis of the findings of this study, we have added standard bupivacaine injections to our separate liposomal bupivacaine injection to cover early postoperative pain. Opioid consumption was significantly lower in the liposomal bupivacaine group than in the ISNB group on postoperative days 2 and 3. We did not measure adverse events related to opioid consumption, so we cannot comment on whether the decreased opioid consumption was associated with the rate of adverse events. However, other studies^21,22 have established this relationship.

We found the liposomal bupivacaine group to have earlier discharges to home. Sixteen of 37 patients in the liposomal bupivacaine group compared with 2 of 21 patients in the ISNB group were discharged on the day after surgery. A mean reduction in LOS of 18 hours for the liposomal bupivacaine group was statistically significant (P = .012). This reduction in LOS has important implications for hospitals and value analysis committees considering whether to keep a new, more expensive local anesthetic on formulary. Savings from reduced LOS and improvements in patient satisfaction may justify the expense (approximately $300 per 266-mg vial) of Exparel.

From a societal cost perspective, liposomal bupivacaine is more economical compared with ISNB, which adds approximately $1500 to the cost of anesthesia per patient.²³ Eliminating the costs associated with ISNB administration in shoulder arthroplasties could result in substantial savings to our healthcare system. More research examining time savings and exact costs of each procedure is needed to determine the true cost effectiveness of each approach.

Limitations of our study include the retrospective design, relatively small numbers of patients in each group, missing data for some patients at various time points, variation in the types of procedures in each group, and lack of long-term outcome measures. It is important to note that we did not confirm the success of the nerve block after administration. However, this study reflects the effectiveness of each of the modalities in actual clinical conditions (as opposed to a controlled experimental setting). The actual effectiveness of a nerve block varies, even when performed by an experienced anesthesiologist with ultrasound guidance. Furthermore, immediate postoperative pain scores in the nerve block group are consistent with those of prior research reporting pain values ranging from 4 to 5 and a mean duration of effect ranging from 9 to 14 hours.^23,24 Additionally, the patients, surgeon, and nursing team were not blinded to the treatment group. Although we did note a significant difference in the types of procedures between groups, this finding is related to the greater number of hemiarthroplasties performed in the ISNB group (N = 5) compared with the liposomal group (N = 1). Because of this variation and the decreased invasiveness of hemiarthroplasties, the bias is against the liposomal group. Finally, our primary outcome variable was pain, which is a subjective, self-reported measure. However, our opioid consumption data and LOS data corroborate the improved pain scores in the liposomal bupivacaine group.

Limiting the study to a single surgeon may limit external validity. Another limitation is the lack of data on adverse events related to opioid medication use. There was no additional experimental group to determine whether less expensive local anesthetics injected locally would perform similarly to liposomal bupivacaine. In total knee arthroplasty, periarticular injections of liposomal bupivacaine were not as effective as less expensive periarticular injections.²⁵ It is unclear which agents (and in what doses or combinations) should be used for periarticular injections. Finally, we acknowledge that our retrospective study design cannot account for all potential factors affecting discharge time.

This is the first comparative study of liposomal bupivacaine and ISNB in TSA. The study design allowed us to control for variables such as surgical technique, postoperative protocols (including use and type of sling), and use of other pain modalities such as patient-controlled analgesia and intravenous acetaminophen that are likely to affect postoperative pain and LOS. This study provides preliminary data that confirm relative equipoise between liposomal bupivacaine and ISNB, which is needed for the ethical conduct of a randomized controlled trial. Such a trial would allow for a more robust comparison, and this retrospective study provides appropriate pilot data on which to base this design and the clinical information needed to counsel patients during enrollment.

Our results suggest that liposomal bupivacaine may provide superior or similar pain relief compared with ISNB after shoulder arthroplasty. Additionally, the use of liposomal bupivacaine was associated with decreased opioid consumption and earlier discharge to home compared with ISNB. These findings have important implications for pain control after TSA because pain represents a major concern for patients and providers after surgery. In addition to clinical improvements, use of liposomal bupivacaine may save time and eliminate costs associated with administering nerve blocks. Local injection may also be used in patients who are contraindicated for ISNB such as those with obesity, pulmonary disease, or peripheral neuropathy. Although we cannot definitively suggest that liposomal bupivacaine is superior to the current gold standard ISNB for pain control after shoulder arthroplasty, our results suggest a relative clinical equipoise between these modalities. Larger analytical studies, including randomized trials, should be performed to explore the potential benefits of liposomal bupivacaine injections for pain control after shoulder arthroplasty.

Am J Orthop. 2016;45(7):424-430. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.

The annual number of total shoulder arthroplasties (TSAs) is rising with the growing elderly population and development of new technologies such as reverse shoulder arthroplasty.¹ In 2008, 47,000 shoulder arthroplasties were performed in the US compared with 19,000 in 1998.¹ As of 2011, there were 53,000 shoulder arthroplasties performed annually.² Pain control after shoulder procedures, particularly TSA, is challenging. ³

Several modalities exist to manage pain after shoulder arthroplasty. The interscalene brachial plexus nerve block is considered the “gold standard” for shoulder analgesia. A new approach is the periarticular injection method, in which the surgeon administers a local anesthetic intraoperatively. Liposomal bupivacaine (Exparel, Pacira Pharmaceuticals, Inc.) is a nonopioid anesthetic that has been shown to improve pain control, shorten hospital stays, and decrease costs for total knee and hip arthroplasty compared with nerve blocks.^4-6 Patients who were treated with liposomal bupivacaine consumed less opioid medication than a placebo group.⁷

Our purpose was to compare intraoperative local liposomal bupivacaine injection with preoperative single-shot interscalene nerve block (ISNB) in terms of pain control, opioid use, and length of hospital stay (LOS) after shoulder arthroplasty. We hypothesized that patients in the liposomal bupivacaine group would have lower pain scores, less opioid use, and shorter LOS compared with patients in the ISNB group.

Methods

A retrospective cohort analysis was conducted with 58 patients who underwent shoulder arthroplasty by 1 surgeon at our academically affiliated community hospital from January 2012 through January 2015. ISNBs were the standard at the beginning of the study period and were used until Exparel became available on the hospital formulary in 2013. We began using Exparel for all shoulder arthroplasties in November 2013. No other changes were made in the perioperative management of our arthroplasty patients during this period. Patients who underwent TSA, reverse TSA, or hemiarthroplasty of the shoulder were included. Patients who underwent revision TSA were excluded. Twenty-one patients received ISNBs and 37 received liposomal bupivacaine injections. This study was approved by our Institutional Review Board.

Baseline data for each patient were age, sex, body mass index, and the American Society of Anesthesiologists (ASA) Physical Status Classification. The primary outcome measure was the numeric rating scale (NRS) pain score at 4 post-operative time intervals. The NRS pain score has a range of 0 to 10, with 10 representing severe pain. Data were gathered from nursing and physical therapy notes in patient charts. The postoperative time intervals were 0 to 1 hour, 8 to 14 hours, 18 to 24 hours, and 27 to 36 hours. Available NRS scores for these time intervals were averaged. Patients were included if they had pain scores for at least 3 of the postoperative time intervals documented in their charts. Secondary outcome measures were LOS and opioid consumption during hospital admission. Intravenous acetaminophen use was also measured in both groups. All data on opioids were converted to oral morphine equivalents using the method described by Schneider and colleagues.⁸

A board-certified, fellowship-trained anesthesiologist, experienced in regional anesthesia, administered the single-shot ISNB before surgery. The block was administered under ultrasound guidance using a 44-mm, 22-gauge needle with the patient in the supine position. No indwelling catheter was used. The medication consisted of 30 mL of 5% ropivacaine (5 mg/mL). The surgeon injected liposomal bupivacaine (266 mg diluted into 40 mL of injectable saline) near the end of the procedure throughout the pericapsular area and multiple layers of the wound, per manufacturer guidelines.⁹ A 60-mL syringe with a 20-gauge needle was used. All operations were performed by 1 board-certified, fellowship-trained surgeon using a standard deltopectoral approach with the same surgical equipment. The same postoperative pain protocol was used for all patients, including intravenous acetaminophen and patient-controlled analgesia. Additional oral pain medication was provided as needed for all patients. Physical therapy protocols were identical between groups.

Statistical Analysis

Mean patient ages in the 2 treatment groups were compared using the Student t test. Sex distribution and the ASA scores were compared using a χ² test and a Fisher exact test, respectively. Arthroplasty types were compared using a Fisher exact test. The medians and interquartile ranges of the NRS scores at each time point measured were tabulated by treatment group, and at each time point the difference between groups was tested using nonparametric rank sum tests.

We tested the longitudinal trajectory of NRS scores over time, accounting for repeated measurements in the same patients using linear mixed model analysis. Treatment group, time period as a categorical variable, and the interaction between treatment and time period were included as fixed effects, and patient identification number was included as the random effect. An initial omnibus test was performed for all treatment and treatment-by-time interaction effects. Subsequently, the treatment-by-time interaction was tested for each of the time periods. The association of day of discharge (as a categorical variable) with treatment was tested using the Fisher exact test. All analyses were conducted using Stata, version 13, software (StataCorp LP). P values <.05 were considered significant.

 

Sample Size Analysis

We calculated the minimum detectable effect size with 80% power at an alpha level of 0.05 for the nonparametric rank sum test in terms of the proportion of every possible pair of patients treated with the 2 treatments, where the patient treated with liposomal bupivacaine has a lower pain score than the patient treated with ISNB. For pain score at 18 to 24 hours, the sample sizes of 33 patients treated with liposomal bupivacaine and 20 treated with ISNB, the minimum detectable effect size is 73%.

Results

Fifty-eight patient charts (21 in the ISNB group and 37 in the liposomal bupivacaine group) were reviewed for the study. Patient sex distribution, mean age, mean body mass index, and mean baseline ASA scores were not statistically different (Table 1).

In the ISNB group, 5 patients had hemiarthroplasty, 12 had TSA, and 4 had reverse TSA. In the liposomal bupivacaine group, 1 patient had hemiarthroplasty, 23 had TSA, and 13 had reverse TSA. Frequency of procedure types was significantly different between groups (P = .039), with the liposomal bupivacaine group undergoing fewer hemiarthroplasties.

The primary outcome measure, NRS pain score, showed no significant differences between groups at 0 to 1 hour after surgery (P = .99) or 8 to 14 hours after surgery (P = .208).

At 18 to 24 hours after surgery, the liposomal bupivacaine group had a lower mean NRS score than the ISNB group (P = .001). This was statistically significant when taking repeated measures of variance into account (Figure 1). Mean NRS score was also lower for the liposomal bupivacaine group at 27 to 36 hours after surgery (P = .029).

This was a significant difference when repeated measures of variance was considered (Table 2).

There was no difference in the amount of intravenous acetaminophen given during the hospital stay between groups. There was no significant difference in opioid consumption on postoperative day 1 in the hospital (P = .59) (Figure 2). However, there were significant differences between groups on postoperative days 2 and 3.

On postoperative day 2, the ISNB group required significantly more opioids (mean, 112 mg morphine equivalents) than the liposomal bupivacaine group (mean, 37 mg morphine equivalents) (P = .001). The ISNB group also required significantly more opioids (mean, 25 mg morphine equivalents) on postoperative day 3 than the liposomal bupivacaine group (mean, 5 mg) (P = .002).

Sixteen of 37 patients in the liposomal bupivacaine group and 2 of 21 in the ISNB group were discharged on the day after surgery (P = .010) (Table 3).

The mean LOS was 46 ± 20 hours for the liposomal bupivacaine group and 57 ± 14 hours for the ISNB group (P = .012).

There were no major cardiac or respiratory events in either group. No long-term paresthesias or neuropathies were noted. There were no readmissions for either group.

Discussion

Postoperative pain control after shoulder arthroplasty can be challenging, and several modalities have been tried in various combinations to minimize pain and decrease adverse effects of opioid medications. The most common method for pain relief after shoulder arthroplasty is the ISNB. Several studies of ISNBs have shown improved pain control after shoulder arthroplasty with associated decreased opioid consumption and related side effects.¹⁰ Patient rehabilitation and satisfaction have improved with the increasing use of peripheral nerve blocks.¹¹

Despite the well-established benefits of ISNBs, several limitations exist. Although the superior portion of the shoulder is well covered by an ISNB, the inferior portion of the brachial plexus can remain uncovered or only partially covered.¹² Complications of ISNBs include hemidiaphragmatic paresis, rebound pain 24 hours after surgery,¹³ chronic neurologic complications,¹⁴ and substantial respiratory and cardiovascular events.¹⁵ Nerve blocks also require additional time and resources in the perioperative period, including an anesthesiologist with specialized training, assistants, and ultrasonography or nerve stimulation equipment contraindicated in patients taking blood thinners.¹⁶

Periarticular injections of local anesthetics have also shown promise in reducing pain after arthroplasty.⁴ Benefits include an enhanced safety profile because local injection avoids the concurrent blockade of the phrenic nerve and recurrent laryngeal nerve and has not been associated with the risk of peripheral neuropathies. Further, local injection is a simple technique that can be performed during surgery without additional personnel or expertise. A limitation of this approach is the relatively short duration of effectiveness of the local anesthetic and uncertainty regarding the best agent and the ideal volume of injection.⁶ Liposomal bupivacaine is a new agent (approved by the US Food and Drug Administration in 2011¹⁷) with a sustained release over 72 to 96 hours.¹⁸ The most common adverse effects of liposomal bupivacaine are nausea, vomiting, constipation, pyrexia, dizziness, and headache.¹⁹ Chondrotoxicity and granulomatous inflammation are more serious, yet rare, complications of liposomal bupivacaine.²⁰

We found that liposomal bupivacaine injections were associated with lower pain scores compared with ISNB at 18 to 24 hours after surgery. This correlated with less opioid consumption in the liposomal bupivacaine group than in the ISNB group on the second postoperative day. These differences in pain values are consistent with the known pharmacokinetics of liposomal bupivacaine.¹⁸ Peak plasma levels normally occur approximately 24 hours after injection, leaving the early postoperative period relatively uncovered by anesthetic agent. This finding of relatively poor pain control early after surgery has also been noted in patients undergoing knee arthroplasty.⁵ On the basis of the findings of this study, we have added standard bupivacaine injections to our separate liposomal bupivacaine injection to cover early postoperative pain. Opioid consumption was significantly lower in the liposomal bupivacaine group than in the ISNB group on postoperative days 2 and 3. We did not measure adverse events related to opioid consumption, so we cannot comment on whether the decreased opioid consumption was associated with the rate of adverse events. However, other studies^21,22 have established this relationship.

We found the liposomal bupivacaine group to have earlier discharges to home. Sixteen of 37 patients in the liposomal bupivacaine group compared with 2 of 21 patients in the ISNB group were discharged on the day after surgery. A mean reduction in LOS of 18 hours for the liposomal bupivacaine group was statistically significant (P = .012). This reduction in LOS has important implications for hospitals and value analysis committees considering whether to keep a new, more expensive local anesthetic on formulary. Savings from reduced LOS and improvements in patient satisfaction may justify the expense (approximately $300 per 266-mg vial) of Exparel.

From a societal cost perspective, liposomal bupivacaine is more economical compared with ISNB, which adds approximately $1500 to the cost of anesthesia per patient.²³ Eliminating the costs associated with ISNB administration in shoulder arthroplasties could result in substantial savings to our healthcare system. More research examining time savings and exact costs of each procedure is needed to determine the true cost effectiveness of each approach.

Limitations of our study include the retrospective design, relatively small numbers of patients in each group, missing data for some patients at various time points, variation in the types of procedures in each group, and lack of long-term outcome measures. It is important to note that we did not confirm the success of the nerve block after administration. However, this study reflects the effectiveness of each of the modalities in actual clinical conditions (as opposed to a controlled experimental setting). The actual effectiveness of a nerve block varies, even when performed by an experienced anesthesiologist with ultrasound guidance. Furthermore, immediate postoperative pain scores in the nerve block group are consistent with those of prior research reporting pain values ranging from 4 to 5 and a mean duration of effect ranging from 9 to 14 hours.^23,24 Additionally, the patients, surgeon, and nursing team were not blinded to the treatment group. Although we did note a significant difference in the types of procedures between groups, this finding is related to the greater number of hemiarthroplasties performed in the ISNB group (N = 5) compared with the liposomal group (N = 1). Because of this variation and the decreased invasiveness of hemiarthroplasties, the bias is against the liposomal group. Finally, our primary outcome variable was pain, which is a subjective, self-reported measure. However, our opioid consumption data and LOS data corroborate the improved pain scores in the liposomal bupivacaine group.

Limiting the study to a single surgeon may limit external validity. Another limitation is the lack of data on adverse events related to opioid medication use. There was no additional experimental group to determine whether less expensive local anesthetics injected locally would perform similarly to liposomal bupivacaine. In total knee arthroplasty, periarticular injections of liposomal bupivacaine were not as effective as less expensive periarticular injections.²⁵ It is unclear which agents (and in what doses or combinations) should be used for periarticular injections. Finally, we acknowledge that our retrospective study design cannot account for all potential factors affecting discharge time.

This is the first comparative study of liposomal bupivacaine and ISNB in TSA. The study design allowed us to control for variables such as surgical technique, postoperative protocols (including use and type of sling), and use of other pain modalities such as patient-controlled analgesia and intravenous acetaminophen that are likely to affect postoperative pain and LOS. This study provides preliminary data that confirm relative equipoise between liposomal bupivacaine and ISNB, which is needed for the ethical conduct of a randomized controlled trial. Such a trial would allow for a more robust comparison, and this retrospective study provides appropriate pilot data on which to base this design and the clinical information needed to counsel patients during enrollment.

Our results suggest that liposomal bupivacaine may provide superior or similar pain relief compared with ISNB after shoulder arthroplasty. Additionally, the use of liposomal bupivacaine was associated with decreased opioid consumption and earlier discharge to home compared with ISNB. These findings have important implications for pain control after TSA because pain represents a major concern for patients and providers after surgery. In addition to clinical improvements, use of liposomal bupivacaine may save time and eliminate costs associated with administering nerve blocks. Local injection may also be used in patients who are contraindicated for ISNB such as those with obesity, pulmonary disease, or peripheral neuropathy. Although we cannot definitively suggest that liposomal bupivacaine is superior to the current gold standard ISNB for pain control after shoulder arthroplasty, our results suggest a relative clinical equipoise between these modalities. Larger analytical studies, including randomized trials, should be performed to explore the potential benefits of liposomal bupivacaine injections for pain control after shoulder arthroplasty.

Am J Orthop. 2016;45(7):424-430. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.

The annual number of total shoulder arthroplasties (TSAs) is rising with the growing elderly population and development of new technologies such as reverse shoulder arthroplasty.¹ In 2008, 47,000 shoulder arthroplasties were performed in the US compared with 19,000 in 1998.¹ As of 2011, there were 53,000 shoulder arthroplasties performed annually.² Pain control after shoulder procedures, particularly TSA, is challenging. ³

Several modalities exist to manage pain after shoulder arthroplasty. The interscalene brachial plexus nerve block is considered the “gold standard” for shoulder analgesia. A new approach is the periarticular injection method, in which the surgeon administers a local anesthetic intraoperatively. Liposomal bupivacaine (Exparel, Pacira Pharmaceuticals, Inc.) is a nonopioid anesthetic that has been shown to improve pain control, shorten hospital stays, and decrease costs for total knee and hip arthroplasty compared with nerve blocks.^4-6 Patients who were treated with liposomal bupivacaine consumed less opioid medication than a placebo group.⁷

Our purpose was to compare intraoperative local liposomal bupivacaine injection with preoperative single-shot interscalene nerve block (ISNB) in terms of pain control, opioid use, and length of hospital stay (LOS) after shoulder arthroplasty. We hypothesized that patients in the liposomal bupivacaine group would have lower pain scores, less opioid use, and shorter LOS compared with patients in the ISNB group.

Methods

A retrospective cohort analysis was conducted with 58 patients who underwent shoulder arthroplasty by 1 surgeon at our academically affiliated community hospital from January 2012 through January 2015. ISNBs were the standard at the beginning of the study period and were used until Exparel became available on the hospital formulary in 2013. We began using Exparel for all shoulder arthroplasties in November 2013. No other changes were made in the perioperative management of our arthroplasty patients during this period. Patients who underwent TSA, reverse TSA, or hemiarthroplasty of the shoulder were included. Patients who underwent revision TSA were excluded. Twenty-one patients received ISNBs and 37 received liposomal bupivacaine injections. This study was approved by our Institutional Review Board.

Baseline data for each patient were age, sex, body mass index, and the American Society of Anesthesiologists (ASA) Physical Status Classification. The primary outcome measure was the numeric rating scale (NRS) pain score at 4 post-operative time intervals. The NRS pain score has a range of 0 to 10, with 10 representing severe pain. Data were gathered from nursing and physical therapy notes in patient charts. The postoperative time intervals were 0 to 1 hour, 8 to 14 hours, 18 to 24 hours, and 27 to 36 hours. Available NRS scores for these time intervals were averaged. Patients were included if they had pain scores for at least 3 of the postoperative time intervals documented in their charts. Secondary outcome measures were LOS and opioid consumption during hospital admission. Intravenous acetaminophen use was also measured in both groups. All data on opioids were converted to oral morphine equivalents using the method described by Schneider and colleagues.⁸

A board-certified, fellowship-trained anesthesiologist, experienced in regional anesthesia, administered the single-shot ISNB before surgery. The block was administered under ultrasound guidance using a 44-mm, 22-gauge needle with the patient in the supine position. No indwelling catheter was used. The medication consisted of 30 mL of 5% ropivacaine (5 mg/mL). The surgeon injected liposomal bupivacaine (266 mg diluted into 40 mL of injectable saline) near the end of the procedure throughout the pericapsular area and multiple layers of the wound, per manufacturer guidelines.⁹ A 60-mL syringe with a 20-gauge needle was used. All operations were performed by 1 board-certified, fellowship-trained surgeon using a standard deltopectoral approach with the same surgical equipment. The same postoperative pain protocol was used for all patients, including intravenous acetaminophen and patient-controlled analgesia. Additional oral pain medication was provided as needed for all patients. Physical therapy protocols were identical between groups.

Statistical Analysis

Mean patient ages in the 2 treatment groups were compared using the Student t test. Sex distribution and the ASA scores were compared using a χ² test and a Fisher exact test, respectively. Arthroplasty types were compared using a Fisher exact test. The medians and interquartile ranges of the NRS scores at each time point measured were tabulated by treatment group, and at each time point the difference between groups was tested using nonparametric rank sum tests.

We tested the longitudinal trajectory of NRS scores over time, accounting for repeated measurements in the same patients using linear mixed model analysis. Treatment group, time period as a categorical variable, and the interaction between treatment and time period were included as fixed effects, and patient identification number was included as the random effect. An initial omnibus test was performed for all treatment and treatment-by-time interaction effects. Subsequently, the treatment-by-time interaction was tested for each of the time periods. The association of day of discharge (as a categorical variable) with treatment was tested using the Fisher exact test. All analyses were conducted using Stata, version 13, software (StataCorp LP). P values <.05 were considered significant.

 

Sample Size Analysis

We calculated the minimum detectable effect size with 80% power at an alpha level of 0.05 for the nonparametric rank sum test in terms of the proportion of every possible pair of patients treated with the 2 treatments, where the patient treated with liposomal bupivacaine has a lower pain score than the patient treated with ISNB. For pain score at 18 to 24 hours, the sample sizes of 33 patients treated with liposomal bupivacaine and 20 treated with ISNB, the minimum detectable effect size is 73%.

Results

Fifty-eight patient charts (21 in the ISNB group and 37 in the liposomal bupivacaine group) were reviewed for the study. Patient sex distribution, mean age, mean body mass index, and mean baseline ASA scores were not statistically different (Table 1).

In the ISNB group, 5 patients had hemiarthroplasty, 12 had TSA, and 4 had reverse TSA. In the liposomal bupivacaine group, 1 patient had hemiarthroplasty, 23 had TSA, and 13 had reverse TSA. Frequency of procedure types was significantly different between groups (P = .039), with the liposomal bupivacaine group undergoing fewer hemiarthroplasties.

The primary outcome measure, NRS pain score, showed no significant differences between groups at 0 to 1 hour after surgery (P = .99) or 8 to 14 hours after surgery (P = .208).

At 18 to 24 hours after surgery, the liposomal bupivacaine group had a lower mean NRS score than the ISNB group (P = .001). This was statistically significant when taking repeated measures of variance into account (Figure 1). Mean NRS score was also lower for the liposomal bupivacaine group at 27 to 36 hours after surgery (P = .029).

This was a significant difference when repeated measures of variance was considered (Table 2).

There was no difference in the amount of intravenous acetaminophen given during the hospital stay between groups. There was no significant difference in opioid consumption on postoperative day 1 in the hospital (P = .59) (Figure 2). However, there were significant differences between groups on postoperative days 2 and 3.

On postoperative day 2, the ISNB group required significantly more opioids (mean, 112 mg morphine equivalents) than the liposomal bupivacaine group (mean, 37 mg morphine equivalents) (P = .001). The ISNB group also required significantly more opioids (mean, 25 mg morphine equivalents) on postoperative day 3 than the liposomal bupivacaine group (mean, 5 mg) (P = .002).

Sixteen of 37 patients in the liposomal bupivacaine group and 2 of 21 in the ISNB group were discharged on the day after surgery (P = .010) (Table 3).

The mean LOS was 46 ± 20 hours for the liposomal bupivacaine group and 57 ± 14 hours for the ISNB group (P = .012).

There were no major cardiac or respiratory events in either group. No long-term paresthesias or neuropathies were noted. There were no readmissions for either group.

Discussion

Postoperative pain control after shoulder arthroplasty can be challenging, and several modalities have been tried in various combinations to minimize pain and decrease adverse effects of opioid medications. The most common method for pain relief after shoulder arthroplasty is the ISNB. Several studies of ISNBs have shown improved pain control after shoulder arthroplasty with associated decreased opioid consumption and related side effects.¹⁰ Patient rehabilitation and satisfaction have improved with the increasing use of peripheral nerve blocks.¹¹

Despite the well-established benefits of ISNBs, several limitations exist. Although the superior portion of the shoulder is well covered by an ISNB, the inferior portion of the brachial plexus can remain uncovered or only partially covered.¹² Complications of ISNBs include hemidiaphragmatic paresis, rebound pain 24 hours after surgery,¹³ chronic neurologic complications,¹⁴ and substantial respiratory and cardiovascular events.¹⁵ Nerve blocks also require additional time and resources in the perioperative period, including an anesthesiologist with specialized training, assistants, and ultrasonography or nerve stimulation equipment contraindicated in patients taking blood thinners.¹⁶

Periarticular injections of local anesthetics have also shown promise in reducing pain after arthroplasty.⁴ Benefits include an enhanced safety profile because local injection avoids the concurrent blockade of the phrenic nerve and recurrent laryngeal nerve and has not been associated with the risk of peripheral neuropathies. Further, local injection is a simple technique that can be performed during surgery without additional personnel or expertise. A limitation of this approach is the relatively short duration of effectiveness of the local anesthetic and uncertainty regarding the best agent and the ideal volume of injection.⁶ Liposomal bupivacaine is a new agent (approved by the US Food and Drug Administration in 2011¹⁷) with a sustained release over 72 to 96 hours.¹⁸ The most common adverse effects of liposomal bupivacaine are nausea, vomiting, constipation, pyrexia, dizziness, and headache.¹⁹ Chondrotoxicity and granulomatous inflammation are more serious, yet rare, complications of liposomal bupivacaine.²⁰

We found that liposomal bupivacaine injections were associated with lower pain scores compared with ISNB at 18 to 24 hours after surgery. This correlated with less opioid consumption in the liposomal bupivacaine group than in the ISNB group on the second postoperative day. These differences in pain values are consistent with the known pharmacokinetics of liposomal bupivacaine.¹⁸ Peak plasma levels normally occur approximately 24 hours after injection, leaving the early postoperative period relatively uncovered by anesthetic agent. This finding of relatively poor pain control early after surgery has also been noted in patients undergoing knee arthroplasty.⁵ On the basis of the findings of this study, we have added standard bupivacaine injections to our separate liposomal bupivacaine injection to cover early postoperative pain. Opioid consumption was significantly lower in the liposomal bupivacaine group than in the ISNB group on postoperative days 2 and 3. We did not measure adverse events related to opioid consumption, so we cannot comment on whether the decreased opioid consumption was associated with the rate of adverse events. However, other studies^21,22 have established this relationship.

We found the liposomal bupivacaine group to have earlier discharges to home. Sixteen of 37 patients in the liposomal bupivacaine group compared with 2 of 21 patients in the ISNB group were discharged on the day after surgery. A mean reduction in LOS of 18 hours for the liposomal bupivacaine group was statistically significant (P = .012). This reduction in LOS has important implications for hospitals and value analysis committees considering whether to keep a new, more expensive local anesthetic on formulary. Savings from reduced LOS and improvements in patient satisfaction may justify the expense (approximately $300 per 266-mg vial) of Exparel.

From a societal cost perspective, liposomal bupivacaine is more economical compared with ISNB, which adds approximately $1500 to the cost of anesthesia per patient.²³ Eliminating the costs associated with ISNB administration in shoulder arthroplasties could result in substantial savings to our healthcare system. More research examining time savings and exact costs of each procedure is needed to determine the true cost effectiveness of each approach.

Limitations of our study include the retrospective design, relatively small numbers of patients in each group, missing data for some patients at various time points, variation in the types of procedures in each group, and lack of long-term outcome measures. It is important to note that we did not confirm the success of the nerve block after administration. However, this study reflects the effectiveness of each of the modalities in actual clinical conditions (as opposed to a controlled experimental setting). The actual effectiveness of a nerve block varies, even when performed by an experienced anesthesiologist with ultrasound guidance. Furthermore, immediate postoperative pain scores in the nerve block group are consistent with those of prior research reporting pain values ranging from 4 to 5 and a mean duration of effect ranging from 9 to 14 hours.^23,24 Additionally, the patients, surgeon, and nursing team were not blinded to the treatment group. Although we did note a significant difference in the types of procedures between groups, this finding is related to the greater number of hemiarthroplasties performed in the ISNB group (N = 5) compared with the liposomal group (N = 1). Because of this variation and the decreased invasiveness of hemiarthroplasties, the bias is against the liposomal group. Finally, our primary outcome variable was pain, which is a subjective, self-reported measure. However, our opioid consumption data and LOS data corroborate the improved pain scores in the liposomal bupivacaine group.

Limiting the study to a single surgeon may limit external validity. Another limitation is the lack of data on adverse events related to opioid medication use. There was no additional experimental group to determine whether less expensive local anesthetics injected locally would perform similarly to liposomal bupivacaine. In total knee arthroplasty, periarticular injections of liposomal bupivacaine were not as effective as less expensive periarticular injections.²⁵ It is unclear which agents (and in what doses or combinations) should be used for periarticular injections. Finally, we acknowledge that our retrospective study design cannot account for all potential factors affecting discharge time.

This is the first comparative study of liposomal bupivacaine and ISNB in TSA. The study design allowed us to control for variables such as surgical technique, postoperative protocols (including use and type of sling), and use of other pain modalities such as patient-controlled analgesia and intravenous acetaminophen that are likely to affect postoperative pain and LOS. This study provides preliminary data that confirm relative equipoise between liposomal bupivacaine and ISNB, which is needed for the ethical conduct of a randomized controlled trial. Such a trial would allow for a more robust comparison, and this retrospective study provides appropriate pilot data on which to base this design and the clinical information needed to counsel patients during enrollment.

Our results suggest that liposomal bupivacaine may provide superior or similar pain relief compared with ISNB after shoulder arthroplasty. Additionally, the use of liposomal bupivacaine was associated with decreased opioid consumption and earlier discharge to home compared with ISNB. These findings have important implications for pain control after TSA because pain represents a major concern for patients and providers after surgery. In addition to clinical improvements, use of liposomal bupivacaine may save time and eliminate costs associated with administering nerve blocks. Local injection may also be used in patients who are contraindicated for ISNB such as those with obesity, pulmonary disease, or peripheral neuropathy. Although we cannot definitively suggest that liposomal bupivacaine is superior to the current gold standard ISNB for pain control after shoulder arthroplasty, our results suggest a relative clinical equipoise between these modalities. Larger analytical studies, including randomized trials, should be performed to explore the potential benefits of liposomal bupivacaine injections for pain control after shoulder arthroplasty.

Am J Orthop. 2016;45(7):424-430. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.

To the Editor:

Prior studies have assessed the quality of text-based dermatology information on the Internet using traditional search engine queries.¹ However, little is understood about the sources, accuracy, and quality of online dermatology images derived from direct image searches. Previous work has shown that direct search engine image queries were largely accurate for 3 pediatric dermatology diagnosis searches: atopic dermatitis, lichen striatus, and subcutaneous fat necrosis.² We assessed images obtained for common dermatologic conditions from a Google image search (GIS) compared to a traditional text-based Google web search (GWS).

Image results for 32 unique dermatologic search terms were analyzed (Table 1). These search terms were selected using the results of a prior study that identified the most common dermatologic diagnoses that led users to the 2 most popular dermatology-specific websites worldwide: the American Academy of Dermatology (www.aad.org) and DermNet New Zealand (www.dermnetnz.org).³ The Alexa directory (www.alexa.com), a large publicly available Internet analytics resource, was used to determine the most common dermatology search terms that led a user to either www.dermnetnz.org or www.aad.org. In addition, searches for the 3 most common types of skin cancer—melanoma, squamous cell carcinoma, and basal cell carcinoma—were included. Each term was entered into a GIS and a GWS. The first 10 results, which represent 92% of the websites ultimately visited by users,⁴ were analyzed. The source, diagnostic accuracy, and Fitzpatrick skin type of the images was determined. Website sources were organized into 11 categories. All data collection occurred within a 1-week period in August 2015.

A total of 320 images were analyzed. In the GIS, private websites (36%), dermatology association websites (28%), and general health information websites (10%) were the 3 most common sources. In the GWS, health information websites (35%), private websites (21%), and dermatology association websites (20%) accounted for the most common sources (Table 2). The majority of images were of Fitzpatrick skin types I and II (89%) and nearly all images were diagnostically accurate (98%). There was no statistically significant difference in accuracy of diagnosis between physician-associated websites (100% accuracy) versus nonphysician-associated sites (98% accuracy, P=.25).

Our results showed high diagnostic accuracy among the top GIS results for common dermatology search terms. Diagnostic accuracy did not vary between websites that were physician associated versus those that were not. Our results are comparable to the reported accuracy of online dermatologic health information.¹ In GIS results, the majority of images were provided by private websites, whereas the top websites in GWS results were health information websites.

Only 1% of images were of Fitzpatrick skin types VI and VII. Presentation of skin diseases is remarkably different based on the patient’s skin type.⁵ The shortage of readily accessible images of skin of color is in line with the lack of familiarity physicians and trainees have with dermatologic conditions in ethnic skin.⁶

Based on the results from this analysis, providers and patients searching for dermatologic conditions via a direct GIS should be cognizant of several considerations. Although our results showed that GIS was accurate, the searcher should note that image-based searches are not accompanied by relevant text that can help confirm relevancy and accuracy. Image searches depend on textual tags added by the source website. Websites that represent dermatological associations and academic centers can add an additional layer of confidence for users. Patients and clinicians also should be aware that the consideration of a patient’s Fitzpatrick skin type is critical when assessing the relevancy of a GIS result. In conclusion, search results via GIS queries are accurate for the dermatological diagnoses tested but may be lacking in skin of color variations, suggesting a potential unmet need based on our growing ethnic skin population.

To the Editor:

Prior studies have assessed the quality of text-based dermatology information on the Internet using traditional search engine queries.¹ However, little is understood about the sources, accuracy, and quality of online dermatology images derived from direct image searches. Previous work has shown that direct search engine image queries were largely accurate for 3 pediatric dermatology diagnosis searches: atopic dermatitis, lichen striatus, and subcutaneous fat necrosis.² We assessed images obtained for common dermatologic conditions from a Google image search (GIS) compared to a traditional text-based Google web search (GWS).

Image results for 32 unique dermatologic search terms were analyzed (Table 1). These search terms were selected using the results of a prior study that identified the most common dermatologic diagnoses that led users to the 2 most popular dermatology-specific websites worldwide: the American Academy of Dermatology (www.aad.org) and DermNet New Zealand (www.dermnetnz.org).³ The Alexa directory (www.alexa.com), a large publicly available Internet analytics resource, was used to determine the most common dermatology search terms that led a user to either www.dermnetnz.org or www.aad.org. In addition, searches for the 3 most common types of skin cancer—melanoma, squamous cell carcinoma, and basal cell carcinoma—were included. Each term was entered into a GIS and a GWS. The first 10 results, which represent 92% of the websites ultimately visited by users,⁴ were analyzed. The source, diagnostic accuracy, and Fitzpatrick skin type of the images was determined. Website sources were organized into 11 categories. All data collection occurred within a 1-week period in August 2015.

A total of 320 images were analyzed. In the GIS, private websites (36%), dermatology association websites (28%), and general health information websites (10%) were the 3 most common sources. In the GWS, health information websites (35%), private websites (21%), and dermatology association websites (20%) accounted for the most common sources (Table 2). The majority of images were of Fitzpatrick skin types I and II (89%) and nearly all images were diagnostically accurate (98%). There was no statistically significant difference in accuracy of diagnosis between physician-associated websites (100% accuracy) versus nonphysician-associated sites (98% accuracy, P=.25).

Our results showed high diagnostic accuracy among the top GIS results for common dermatology search terms. Diagnostic accuracy did not vary between websites that were physician associated versus those that were not. Our results are comparable to the reported accuracy of online dermatologic health information.¹ In GIS results, the majority of images were provided by private websites, whereas the top websites in GWS results were health information websites.

Only 1% of images were of Fitzpatrick skin types VI and VII. Presentation of skin diseases is remarkably different based on the patient’s skin type.⁵ The shortage of readily accessible images of skin of color is in line with the lack of familiarity physicians and trainees have with dermatologic conditions in ethnic skin.⁶

Based on the results from this analysis, providers and patients searching for dermatologic conditions via a direct GIS should be cognizant of several considerations. Although our results showed that GIS was accurate, the searcher should note that image-based searches are not accompanied by relevant text that can help confirm relevancy and accuracy. Image searches depend on textual tags added by the source website. Websites that represent dermatological associations and academic centers can add an additional layer of confidence for users. Patients and clinicians also should be aware that the consideration of a patient’s Fitzpatrick skin type is critical when assessing the relevancy of a GIS result. In conclusion, search results via GIS queries are accurate for the dermatological diagnoses tested but may be lacking in skin of color variations, suggesting a potential unmet need based on our growing ethnic skin population.

To the Editor:

Prior studies have assessed the quality of text-based dermatology information on the Internet using traditional search engine queries.¹ However, little is understood about the sources, accuracy, and quality of online dermatology images derived from direct image searches. Previous work has shown that direct search engine image queries were largely accurate for 3 pediatric dermatology diagnosis searches: atopic dermatitis, lichen striatus, and subcutaneous fat necrosis.² We assessed images obtained for common dermatologic conditions from a Google image search (GIS) compared to a traditional text-based Google web search (GWS).

Image results for 32 unique dermatologic search terms were analyzed (Table 1). These search terms were selected using the results of a prior study that identified the most common dermatologic diagnoses that led users to the 2 most popular dermatology-specific websites worldwide: the American Academy of Dermatology (www.aad.org) and DermNet New Zealand (www.dermnetnz.org).³ The Alexa directory (www.alexa.com), a large publicly available Internet analytics resource, was used to determine the most common dermatology search terms that led a user to either www.dermnetnz.org or www.aad.org. In addition, searches for the 3 most common types of skin cancer—melanoma, squamous cell carcinoma, and basal cell carcinoma—were included. Each term was entered into a GIS and a GWS. The first 10 results, which represent 92% of the websites ultimately visited by users,⁴ were analyzed. The source, diagnostic accuracy, and Fitzpatrick skin type of the images was determined. Website sources were organized into 11 categories. All data collection occurred within a 1-week period in August 2015.

A total of 320 images were analyzed. In the GIS, private websites (36%), dermatology association websites (28%), and general health information websites (10%) were the 3 most common sources. In the GWS, health information websites (35%), private websites (21%), and dermatology association websites (20%) accounted for the most common sources (Table 2). The majority of images were of Fitzpatrick skin types I and II (89%) and nearly all images were diagnostically accurate (98%). There was no statistically significant difference in accuracy of diagnosis between physician-associated websites (100% accuracy) versus nonphysician-associated sites (98% accuracy, P=.25).

Our results showed high diagnostic accuracy among the top GIS results for common dermatology search terms. Diagnostic accuracy did not vary between websites that were physician associated versus those that were not. Our results are comparable to the reported accuracy of online dermatologic health information.¹ In GIS results, the majority of images were provided by private websites, whereas the top websites in GWS results were health information websites.

Only 1% of images were of Fitzpatrick skin types VI and VII. Presentation of skin diseases is remarkably different based on the patient’s skin type.⁵ The shortage of readily accessible images of skin of color is in line with the lack of familiarity physicians and trainees have with dermatologic conditions in ethnic skin.⁶

Based on the results from this analysis, providers and patients searching for dermatologic conditions via a direct GIS should be cognizant of several considerations. Although our results showed that GIS was accurate, the searcher should note that image-based searches are not accompanied by relevant text that can help confirm relevancy and accuracy. Image searches depend on textual tags added by the source website. Websites that represent dermatological associations and academic centers can add an additional layer of confidence for users. Patients and clinicians also should be aware that the consideration of a patient’s Fitzpatrick skin type is critical when assessing the relevancy of a GIS result. In conclusion, search results via GIS queries are accurate for the dermatological diagnoses tested but may be lacking in skin of color variations, suggesting a potential unmet need based on our growing ethnic skin population.

This issue of the Journal of Hospital Medicine describes 2 research and quality improvement demonstration projects funded by the Gordon and Betty Moore Foundation. Early detection is central to both projects. This introductory article does not provide a global review of the now voluminous literature on rapid response teams (RRTs), sepsis detection systems, or treatment protocols. Rather, it takes a step back and reassesses just what early detection and quantification of critical illness are. It then examines the implications of early detection and its quantification.

CONCEPTUAL FRAMEWORK

We define severe illness as the presence of acute disease such that a person can no longer expect to improve without dedicated hospital treatment but which is not inevitably associated with mortality, postdischarge morbidity, or major loss of autonomy. In contrast, we define critical illness as acute disease with high a priori risk of mortality, postdischarge morbidity, and major (possibly total) loss of autonomy. We accept that the boundaries between ordinary illness, severe illness, and critical illness are blurred. The basic assumption behind all efforts at early detection is that these edges can be made sharp, and that the knowledge base required to do so can also lead to improvements in treatment protocols and patient outcomes. Further, it is assumed that at least some forms of critical illness can be prevented or mitigated by earlier detection, identification, and treatment.

Research over the last 2 decades has provided important support for this intuitive view as well as making it more nuanced. With respect to epidemiology, the big news is that sepsis is the biggest culprit, and that it accounts for a substantial proportion of all hospital deaths, including many previously considered unexpected hospital deaths due to in‐hospital deterioration.[1] With respect to treatment, a number of studies have demonstrated that crucial therapies previously considered to be intensive care unit (ICU) therapies can be initiated in the emergency department or general medicalsurgical ward.[2]

Figure 1 shows an idealized framework for illness presenting in the emergency department or general medicalsurgical wards. It illustrates the notion that a transition period exists when patients may be rescued with less intense therapy than will be required when condition progression occurs. Once a certain threshold is crossed, the risk of death or major postdischarge morbidity rises exponentially. Unaided human cognition's ability to determine where a given patient is in this continuum is dangerously variable and is highly dependent on the individuals training and experience. Consequently, as described in several of the articles in this issue as well as multiple other publications, health systems are employing comprehensive electronic medical records (EMRs) and are migrating to algorithmic approaches that combine multiple types of patient data.[3, 4] Although we are still some distance from being able to define exact boundaries between illness, severe illness, and critical illness, current EMRs permit much better definition of patient states, care processes, and short‐term outcomes.

Figure 1

Whereas our ability to quantify many processes and short‐term outcomes is expanding rapidly, quantification of the possible benefit of early detection is complicated by the fact that, even in the best of circumstances, not all patients can be rescued. For some patients, rescue may be temporary, raising the prospect of repeated episodes of critical illness and prolonged intensive care without any hope of leaving the hospital. Figure 2 shows that, for these patients, the problem is no longer simply one of preventing death and preserving function but, rather, preserving autonomy and dignity. In this context, early detection means earlier specification of patient preferences.[5, 6]

Figure 2

JUST WHAT CONSTITUTES EARLY DETECTION (AND HOW DO WE QUANTIFY IT)?

RRTs arose as the result of a number of studies showing thatin retrospectin‐hospital deteriorations should not have been unexpected. Given comprehensive inpatient EMRs, it is now possible to develop more rigorous definitions. A minimum set of parameters that one would need to specify for proper quantification of early detection is shown on Figure 3. The first is specifying a T₀, that is, the moment when a prediction regarding event X (which needs to be defined) is issued. This is different from the (currently unmeasurable) biologic onset of illness as well as the first documented indication that critical illness was present. Further, it is important to be explicit about the event time frame (the time period during which a predicted event is expected to occur): we are predicting that X will occur within E hours of the T₀. The time frame between the T₀ and X, which we are referring to as lead time, is clinically very important, as it represents the time period during which the response arm (eg, RRT intervention) is to be instituted. Statistical approaches can be used to estimate it, but once an early detection system is in place, it can be quantified. Figure 3 is not restricted to electronic systems; all components shown can be and are used by unaided human cognition.

Figure 3

Figure 4

It is essential to specify what data are used to generate probability estimates as well as the time frames used, which we refer to as the look‐back time frames. Several types of data could be employed, with some data elements (eg, age or gender) being discrete data with a 1:1 fixed correspondence between the patient and the data. Other data have a many‐to‐1 relationship, and an exact look‐back time frame must be specified for each data type. For example, it seems reasonable to specify a short (1224 hours) look‐back period for some types of data (eg, vital signs, lactate, admission diagnosis or chief complaint), an intermediate time period (13 days) for information on the current encounter, and a longer (months to years) time period for preexisting illness or comorbidity burden.

Because many events are rare, traditional measures used to assess model performance, such as the area under the receiver operator characteristic curve (C statistic), are not as helpful.[7] Consequently, much more emphasis needs to be given to 2 key metrics: number needed to evaluate (or workup to detection ratio) and threshold‐specific sensitivity (ability of the alert to detect X at a given threshold). With these, one can answer 3 questions that will be asked by the physicians and nurses who are not likely to be researchers, and who will have little interest in the statistics: How many patients do I need to work up each day? How many patients will I need to work up for each possible outcome identified? For this amount of work, how many of the possible outcomes will we catch?

Data availability for the study of severe and critical illness continues to expand. Practically, this means that future research will require more nuanced ontologies for the classification of physiologic derangement. Current approaches to severity scoring (collapsing data into composite scores) need to be replaced by dynamic approaches that consider differential effects on organ systems as well as what can be measured. Severity scoring will also need to incorporate the rate of change of a score (or probability derived from a score) in predicting the occurrence of an event of interest as well as judging response to treatment. Thus, instead of at time of ICU admission, the patient had a severity score of 76, we may have although this patient's severity score at the time of admission was decreasing by 4 points per hour per 10 mL/kg fluid given, the probability for respiratory instability was increasing by 2.3% per hour given 3 L/min supplemental oxygen. This approach is concordant with work done in other clinical settings (eg, in addition to an absolute value of maximal negative inspiratory pressure or vital capacity, the rate of deterioration of neuromuscular weakness in Guillain‐Barr syndrome is also important in predicting respiratory failure[8]).

Electronic data also could permit better definition of patient preferences regarding escalation of care. At present, available electronic data are limited (primarily, orders such as do not resuscitate).[9] However, this EMR domain is gradually expanding.[10, 11] Entities such as the National Institutes of Health could develop sophisticated and rapid questionnaires around patient preferences that are similar to those developed for the Patient Reported Outcomes Measurement Information System.[12] Such tools could have a significant effect on our ability to quantify the benefits of early detection as it relates to a patient's preferences (including better delineation of what treatments they would and would not want).

ACTIVATING A RESPONSE ARM

Early identification, antibiotic administration, fluid resuscitation, and source control are now widely felt to constitute low‐hanging fruit for decreasing morbidity and mortality in severe sepsis. All these measures are included in quality improvement programs and sepsis bundles.[13, 14, 15] However, before early interventions can be instituted, sepsis must at least be suspected, hence the need for early detection. The situation with respect to patient deterioration (for reasons other than sepsis) in general medical surgical wards is less clear‐cut. Reasons for deterioration are much more heterogenous and, consequently, early detection is likely necessary but not sufficient for outcomes improvement.

The 2 projects described in this issue describe nonspecific (indicating elevated risk but not specifying what led to the elevation of risk) and sepsis‐specific alerting systems. In the case of the nonspecific system, detection may not lead to an immediate deployment of a response arm. Instead, a secondary evaluation process must be triggered first. Following this evaluation component, a response arm may or may not be required. In contrast, the sepsis‐specific project essentially transforms the general medicalsurgical ward into a screening system. This screening system then also triggers specific bundle components.

Neither of these systems relies on unaided human cognition. In the case of the nonspecific system, a complex equation generates a probability that is displayed in the EMR, with protocols specifying what actions are to be taken when that probability exceeds a prespecified threshold. With respect to the sepsis screening system, clinicians are supported by EMR alerts as well as protocols that increase nursing autonomy when sepsis is suspected.

The distinction between nonspecific (eg, acute respiratory failure or hemodynamic deterioration) and specific (eg, severe sepsis) alerting systems is likely to disappear as advances in the field occur. For example, incorporation of natural language processing would permit inclusion of semantic data, which could be processed so as to prebucket an alert into one that not just gave a probability, but also a likely cause for the elevated probability.

In addition, both types of systems suffer from the limitation of working off a limited database because, in general, current textbooks and training programs primary focus remains that of treatment of full‐blown clinical syndromes. For example, little is known about how one should manage patients with intermediate lactate values, despite evidence showing that a significant percentage of patients who die from sepsis will initially have such values, with 1 study showing 63% as many deaths with initial lactate of 2.5 to 4.0 mmol/L as occurred with an initial lactate of >4.0 mmol/L.[16] Lastly, as is discussed below, both systems will encounter similar problems when it comes to quantifying benefit.

QUANTIFYING BENEFIT

Whereas the notion of deploying RRTs has clearly been successful, success in demonstrating unequivocal benefit remains elusive.[17, 18, 19] Outcome measures vary dramatically across studies and have included the number of RRT calls, decreases in code blue events on the ward, and decreases in inpatient mortality.[20] We suspect that other reasons are behind this problem. First is the lack of adequate risk adjustment and ignoring the impact of patients near the end of life on the denominator. Figure 4 shows recent data from 21 Kaiser Permanente Northern California (KPNC) hospitals, which can now capture care directive orders electronically,[21] illustrates this problem. The majority (53%) of hospital deaths occur among a highly variable proportion (range across hospitals, 6.5%18.0%) of patients who arrive at the hospital with a restricted resuscitation preference (do not resuscitate, partial code, and comfort care only). These patients do not want to die or crash and burn but, were they to trigger an alert, they would not necessarily want to be rescued by being transferred to the ICU either; moreover, internal KPNC analyses show that large numbers of these patients have sepsis and refuse aggressive treatment. The second major confounder is that ICUs save lives. Consequently, although early detection could lead to fewer transfers to the ICU, using the end point of ICU admission is very problematic, because in many cases the goal of alerting systems should be to get patients to the ICU sooner, which would not affect the outcome of transfer to the ICU in a downward direction; in fact, such systems might increase transfer to the ICU.

The complexities summarized in Figure 4 mean that it is likely that formal quantification of benefit will require examination of multiple measures, including balancing measures as described below. It is also evident that, in this respectlack of agreement as to what constitutes a good outcomethe issues being faced here are a reflection of a broader area of disagreement within our profession and society at large that extends to medical conditions other than critical illness.

POTENTIAL HARMS OF EARLY DETECTION

Implementation of early detection and rapid response systems are not inherently free of harm. If these systems are not shown to have benefit, then the cost of operating them is moving resources away from other, possibly evidence‐based, interventions.[22] At the individual level, alerts could frighten patients and their families (for example, some people are very uncomfortable with the idea that one can predict events). Physicians and nurses who work in the hospital are already quite busy, so every time an alert is issued, it adds to the demand on their already limited time, hence, the critical importance of strategies to minimize false alarms and alert fatigue. Moreover, altering existing workflows can be disruptive and unpopular.

A potentially more quantifiable problem is the impact of early detection systems on ICU operations. For example, if an RRT decides to transfer a patient from the ward to the ICU as a preventive measure (soft landing) and this in turn ties up an ICU bed, that bed is then unavailable for a new patient in the emergency department. Similarly, early detection systems coupled with structured protocols for promoting soft landings could result in a change in ICU case mix, with greater patient flow due to increased numbers of patients with lower severity and lower ICU length of stay. These considerations suggest the need to couple early detection with other supportive data systems and workflows (eg, systems that monitor bed capacity proactively).

Lastly, if documentation protocols are not established and followed, early detection systems could expose both individual clinicians as well as healthcare institutions to medicallegal risk. This consideration could be particularly important in those instances where an alert is issued and, for whatever reasons, clinicians do not take action and do not document that decision. At present, early detection systems are relatively uncommon, but they may gradually become standard of care. This means that in‐house out of ICU deteriorations, which are generally considered to be bad luck or due to a specific error or oversight, may then be considered to be preventable. Another possible scenario that could arise is that of plaintiffs invoking enterprise liability, where a hospital's not having an early detection system becomes considered negligent.

ARTICLES IN THIS ISSUE

In this issue of the Journal of Hospital Medicine, we examine early detection from various perspectives but around a common theme that usually gets less attention in the academic literature: implementation. The article by Schorr et al.[23] describes a disease‐specific approach that can be instantiated using either electronic or paper tools. Escobar et al.[24] describe the quantitative as well as the electronic architecture of an early warning system (EWS) pilot at 2 hospitals that are part of an integrated healthcare delivery system. Dummett et al.[25] then show how a clinical rescue component was developed to take advantage of the EWS, whereas Granich et al.[26] describe the complementary component (integration of supportive care and ensuring that patient preferences are respected). The paper by Liu et al.[27] concludes by placing all of this work in a much broader context, that of the learning healthcare system.

FUTURE DIRECTIONS: KEY GAPS IN THE FIELD

Important gaps remain with respect to early detection and response systems. Future research will need to focus on a number of areas. First and foremost, better approaches to quantifying the costbenefit relationships of these systems are needed; somehow, we need to move beyond a purely intuitive sense that they are good things. Related to this is the need to establish metrics that would permit rigorous comparisons between different approaches; this work needs to go beyond simple comparisons of the statistical characteristics of different predictive models. Ideally, it should include comparisons of different approaches for the response arms as well. We also need to characterize clinician understanding about detection systems, what constitutes impending or incipient critical illness, and the optimum way to provide early detection. Finally, better approaches to integrating health services research with basic science work must be developed; for example, how should one test new biomarkers in settings with early detection and response systems?

The most important frontier, however, is how one can make early detection and response systems more patient centered and how one can enhance their ability to respect patient preferences. Developing systems to improve clinical management is laudable, but somehow we need to also find ways to have these systems make a better connection to what patients want most and what matters most to them, something that may need to include new ways that sometimes suspend use of these systems. At the end of the day, after early detection, patients must have a care experience that they see as an unequivocal improvement.

Acknowledgements

The authors thank our 2 foundation program officers, Dr. Marybeth Sharpe and Ms. Kate Weiland, for their administrative support and encouragement. The authors also thank Dr. Tracy Lieu, Dr. Michelle Caughey, Dr. Philip Madvig, and Ms. Barbara Crawford for their administrative assistance, Dr. Vincent Liu for comments on the manuscript, and Ms. Rachel Lesser for her help with formatting the manuscript and figures.

Disclosures

This work was supported by the Gordon and Betty Moore Foundation, The Permanente Medical Group, Inc., and Kaiser Foundation Hospitals, Inc. As part of our agreement with the Moore Foundation, we made a commitment to disseminate our findings in articles such as this one. However, the Gordon and Betty Moore Foundation and its staff played no role in how we actually structured our articles, nor did they review or preapprove any of the manuscripts submitted as part of the dissemination component. None of the authors has any conflicts of interest to declare of relevance to this work.