Joshua S. Dines, MD

ABSTRACT

Despite advancements in surgical technique and understanding of throwing mechanics, controversy persists regarding the treatment of grade III acromioclavicular (AC) joint separations, particularly in throwing athletes. Twenty-eight major league baseball (MLB) orthopedic team physicians were surveyed to determine their definitive management of a grade III AC separation in the dominant arm of a professional baseball pitcher and their experience treating AC joint separations in starting pitchers and position players. Return-to-play outcomes were also evaluated. Twenty (71.4%) team physicians recommended nonoperative intervention compared to 8 (28.6%) who would have operated acutely. Eighteen (64.3%) team physicians had treated at least 1 professional pitcher with a grade III AC separation; 51 (77.3%) pitchers had been treated nonoperatively compared to 15 (22.7%) operatively. No difference was observed in the proportion of pitchers who returned to the same level of play (P = .54), had full, unrestricted range of motion (P = .23), or had full pain relief (P = .19) between the operatively and nonoperatively treated MLB pitchers. The majority (53.6%) of physicians would not include an injection if the injury was treated nonoperatively. Open coracoclavicular reconstruction (65.2%) was preferred for operative cases; 66.7% of surgeons would also include distal clavicle excision as an adjunct procedure. About 90% of physicians would return pitchers to throwing >12 weeks after surgery compared to after 4 to 6 weeks in nonoperatively treated cases. In conclusion, MLB team physicians preferred nonoperative management for an acute grade III AC joint separation in professional pitchers. If operative intervention is required, ligament reconstruction with adjunct distal clavicle excision were the most commonly performed procedures.

Continue to: Despite advancements in surgucal technique...

Despite advancements in surgical technique and improved understanding of the physiology of throwing mechanics, controversy persists regarding the preferred treatment for grade III acromioclavicular (AC) joint separations.^1-6 Nonsurgical management has demonstrated return to prior function with fewer complications.⁷ However, there is a growing body of evidence demonstrating that surgical intervention is associated with more favorable outcomes⁸ and should be considered in patients who place high functional demands on their shoulders.⁹

The reported results on professional athletes in the literature remain ambivalent. Multiple small case reports/series have reported successful nonoperative treatment of elite athletes.^10-12 Not surprisingly, McFarland and colleagues¹³ reported in 1997 that 69% of major league baseball (MLB) team physicians preferred nonoperative treatment for a theoretical starting pitcher sustaining a grade III AC separation 1 week prior to the start of the season. In contrast, reports of an inability to throw at a pre-injury level are equally commonplace.^14,15 Nevertheless, all of these studies were limited to small cohorts, as the incidence of grade III AC separations in elite throwing athletes is relatively uncommon.^13,16

In this study, we re-evaluated the study performed by McFarland and colleagues¹³ in 1997 by surveying all active MLB team orthopedic surgeons. We asked them how they would treat a grade III AC separation in a starting professional baseball pitcher. The physicians were also asked about their personal experience evaluating outcomes in these elite athletes. Given our improved understanding of the anatomy, pathophysiology, and surgical techniques for treating grade III AC separations, we hypothesize that more MLB team physicians would favor operative intervention treatment in professional baseball pitchers, as their vocation places higher demands on their shoulders.

MATERIALS AND METHODS

A questionnaire (Appendix A) was distributed to the team physicians of all 30 MLB teams. In addition to surgeon demographics, including age, years in practice, and years of taking care of an MLB team, the initial section of the questionnaire asked orthopedic surgeons how they would treat a theoretical starting pitcher who sustained a grade III AC joint separation of the dominant throwing arm 1 week prior to the start of the season. Physicians who preferred nonoperative treatment were asked whether they would use an injection (and what type), as well as when they would allow the pitcher to start a progressive interval throwing program. Physicians who preferred operative treatment were asked to rank their indications for operating, what procedure they would use (eg, open vs arthroscopic or coracoclavicular ligament repair vs reconstruction), and whether the surgical intervention would include distal clavicle excision. Both groups of physicians were also asked if their preferred treatment would change if the injury were to occur at the end of the season.

The second portion of the questionnaire asked surgeons about their experience treating AC joint separations in both starting pitchers and position players, as well as to describe the long-term outcomes of their preferred treatment, including time to return to full clearance for pitching, whether their patients returned to their prior level of play, and whether these patients had full pain relief. Finally, physicians were asked if any of the nonoperatively treated players ultimately crossed over and required operative intervention.

Continue to: Statistics...

STATISTICS

Descriptive statistics were used for continuous variables, and frequencies were used for categorical variables. Linear regression was performed to determine the correlation between the physician’s training or experience in treating AC joint separations and their recommended treatment. Fischer’s exact test/chi-square analysis was used to compare categorical variables. All tests were conducted using 2-sided hypothesis testing with statistical significance set at P < .05. All statistical analyses were conducted with SPSS 21.0 software (IBM Corporation).

RESULTS

A total of 28 MLB team physicians completed the questionnaires from 18 of the 30 MLB teams. The average age of the responders was 50.5 years (range, 34-60 years), with an average of 18.2 years in practice (range, 2-30 years) and 10.8 years (range, 1-24 years) taking care of their current professional baseball team. About 82% of the team physicians completed a sports medicine fellowship. On average, physicians saw 16.6 (range, 5-50) grade III or higher AC joint separations per year, and operated on 4.6 (range, 0-10) per year.

Nonoperative treatment was the preferred treatment for a grade III AC joint separation in a starting professional baseball pitcher for the majority of team physicians (20/28). No correlation was observed between the physician’s age (P = .881), years in practice (P = .915), years taking care of their professional team (P = .989), percentage of practice focused on shoulders (P = .986), number of AC joint injuries seen (P = .325), or number of surgeries performed per year (P = .807) with the team physician’s preferred treatment. Compared to the proportion reported originally by McFarland and colleagues¹³ in 1997 (69%), there was no difference in the proportion of team physicians that recommended nonoperative treatment (P = 1).

If treating this injury nonoperatively, 46.4% of physicians would also use an injection, with orthobiologics (eg, platelet-rich plasma) as the most popular choice (Table 1). No consensus was provided on the timeframe to return pitchers back to a progressive interval throwing program; however, 46.67% of physicians would return pitchers 4 to 6 weeks after a nonoperatively treated injury, while 35.7% would return pitchers 7 to 12 weeks after the initial injury.

Table 1. Treatment Preferences of Grade III AC Separation by MLB Team Physicians

^aRespondents were allowed to choose more than 1 treatment in each category. ^bChosen as an adjunct treatment.

Abbreviations: AC, acromioclavicular; MLB, major league baseball.

Most physicians (64.3%) cited functional limitations as the most important reason for indicating operative treatment, followed by pain (21.4%), and a deformity (14.3%). About 65% preferred open coracoclavicular ligament reconstruction. No physician recommended the Weaver-Dunn procedure or use of hardware (eg, hook plate). Of those who preferred an operative intervention, 66.7% would also include a distal clavicle excision, which is significantly higher than the proportion reported by McFarland and colleagues¹³ (23%, P = .0170). About 90% of physicians would return pitchers to play >12 weeks after operative treatment.

Continue to: If the injury occurred at the end ...

If the injury occurred at the end of the season, 7 of the 20 orthopedists (35%) who recommended nonoperative treatment said they would change to an operative intervention. Eighteen of 28 responders would have the same algorithm for MLB position players. Team physicians were less likely to recommend operative intervention in position players due to less demand on the arm and increased ability to accommodate the injury by altering their throwing mechanics.

Eighteen (64%) of the team physicians had treated at least 1 professional pitcher with a grade III AC separation in his dominant arm, and 11 (39.3%) had treated >1. Collectively, team physicians had treated 15 professional pitchers operatively, and 51 nonoperatively; only 3 patients converted to operative intervention after a failed nonoperative treatment.

Of the pitchers treated operatively, 93.3% (14) of pitchers returned to their prior level of pitching. The 1 patient who failed to return to the same level of pitching retired instead of returning to play. About 80% (12) of the pitchers had full pain relief, and 93.3% (14) had full range of motion (ROM). The pitcher who failed to regain full ROM also had a concomitant rotator cuff repair. The only complication reported from an operative intervention was a pitcher who sustained a coracoid fracture 10 months postoperatively while throwing 100 mph. Of the pitchers treated nonoperatively, 96% returned to their prior level of pitching, 92.2% (47) had full complete pain relief when throwing, and 100% had full ROM. No differences were observed between the proportion of pitchers who returned to their prior level of pitching, regained full ROM, or had full pain relief in the operative and nonoperative groups (Table 2).

Table 2. Outcomes of Treatment of Grade III AC Separation in 58 Professional Baseball Players

Abbreviations: AC, acromioclavicular; ROM, range of motion.

DISCUSSION 

Controversy persists regarding the optimal management of acute grade III AC separations, with the current available evidence potentially suggesting better cosmetic and radiological results but no definite differences in clinical results.^1-6,17,18 In the absence of formal clinical practice guidelines, surgeons rely on their own experience or defer to the anecdotal experience of experts in the field. Our initial hypothesis was false in this survey of MLB team physicians taking care of overhead throwing athletes at the highest level. Our results demonstrate that despite improved techniques and an increased understanding of the pathophysiology of AC joint separations, conservative management is still the preferred treatment for acute grade III AC joint separations in professional baseball pitchers. The proportion of team physicians recommending nonoperative treatment in our series was essentially equivalent to the results reported by McFarland and colleagues¹³ in 1997, suggesting that the pendulum continues to favor conservative management initially. This status quo likely reflects both the dearth of literature suggesting a substantial benefit of acute operative repair, as well as the ability to accommodate with conservative measures after most grade III AC injuries, even at the highest level of athletic competition.

These results are also consistent with trends from the last few decades. In the 1970s, the overwhelming preference for treating an acute complete AC joint separation was surgical repair, with Powers and Bach¹⁰ reporting in a 1974 survey of 163 chairmen of orthopedic programs around the country that 91.5% advocated surgical treatment. However, surgical preference had reversed by the 1990s. Of the 187 chairmen and 59 team physicians surveyed by Cox¹⁹ in 1992, 72% and 86% respectively preferred nonoperative treatment in a theoretical 21-year-old athlete with a grade III AC separation. Nissen and Chatterjee²⁰ reported in 2007 on a survey of all American Orthopaedic Society for Sports Medicine surgeons (N = 577) and Accreditation Council for Graduate Medical Education orthopedic program residency directors (N = 87) that >80% of responders preferred conservative measures for this acute injury. The reversal of trends has also been corroborated by recent multicenter trials demonstrating no difference in clinical outcomes between operative and nonoperative treatment of high grade AC joint dislocations, albeit these patients were not all high level overhead throwing athletes.^17,18

Continue to: The trends in surgical interventions are notable...

The trends in surgical interventions are notable within the smaller subset of patients who are indicated for operative repair. Use of hardware and primary ligament repair, while popular in the surveys conducted in the 1970s¹⁰ and 1990s¹³ and even present in Nissen and Chatterjee’s²⁰ 2007 survey, were noticeably absent from our survey results, with the majority of respondents preferring open coracoclavicular ligament reconstruction. The role of distal clavicle excision has also expanded, from 23% of team physicians recommending it in 1997¹³ to 57% to 59% in Nissen and Chatterjee’s²⁰ 2007 survey, to 66.7% in our series. This trend is not surprising as several recent cadaveric biomechanical studies have demonstrated that not only do peak graft forces not increase significantly,²¹ the anterior-posterior and superior-inferior motion at the AC joint following ligament reconstruction is maintained despite resection of the lateral clavicle.²² Additionally, primary distal clavicle excision may prevent the development of post-traumatic arthritis at the AC joint and osteolysis of the distal clavicle as a possible pain generator in the future.²³ However, some respondents cautioned against performing a concomitant distal clavicle excision, as some biomechanical data demonstrate that resecting the distal clavicle may lead to increased horizontal translation at the AC joint despite intact superior and posterior AC capsules.²⁴ Professional baseball pitchers may also be more lax and thus prone to more instability. Primary repair or reconstruction may not always lead to complete pre-injury stability in these individuals. This subtle unrecognized instability is hard to diagnosis and may be a persistent source of pain; thus, adding a distal clavicle excision may actually exacerbate the instability.

The nuanced indications for operative intervention, such as the presence of associated lesions were not captured by our survey.²⁵ While most team physicians cited functional limitations as their most common reason for offering surgery, several MLB orthopedic surgeons also commented on evaluating the stability of the AC joint after a grade III injury, akin to the consensus statement from the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) Upper Extremity Committee²⁶ in 2014 that diversified the Rockwood Grade III AC joint separation into its IIIA and IIIB classifications. The ISAKOS recommendations include initial conservative management and a second evaluation (both clinical and radiographic) for grade III lesions 3 to 6 weeks after the injury. However, as professional baseball is an incredibly profitable sport with an annual revenue approaching $9.5 billion²⁷ and pitching salaries up to $32.5 million in 2015, serious financial considerations must be given to players who wish to avoid undergoing delayed surgery.

This study has shortcomings typical of expert opinion papers. The retrospective nature of this study places the data at risk of recall bias. Objective data (eg, terminal ROM, pain relief, and return to play) were obtained from a retrospective chart review; however, no standard documentation or collection method was used given the number of surgeons involved and, thus, conclusions based on treatment outcomes are imperfect. Another major weakness of this survey is the relatively small number of patients and respondents. An a priori power analysis was not available, as this was a retrospective review. A comparative trial will be necessary to definitively support one treatment over another. Assuming a 95% return to play in the nonoperatively treated group, approximately 300 patients would be needed in a prospective 2-armed study with 80% power to detect a 10% reduction in the incidence of return to play using an alpha level of 0.05 and assuming no loss to follow-up. This sample size would be difficult to achieve in this patient population.

However, compared to past series,¹³ the number of professional baseball players treated by the collective experience of these MLB team physicians is the largest reported to date. As suggested above, the rarity of this condition in elite athletes precludes the ability to have matched controls to definitively determine the optimal treatment, which may explain the lack of difference in the return to play, ROM, and pain relief outcomes. Instead, we can only extrapolate based on the collective anecdotal experience of the MLB team physicians.

CONCLUSION

Despite advances in surgical technique and understanding of throwing mechanics, the majority of MLB team physicians preferred nonoperative management for an acute grade III AC joint separation in a professional baseball pitcher. Open coracoclavicular ligament reconstruction was preferred for those who preferred operative intervention. An increasing number of orthopedic surgeons now consider a distal clavicle excision as an adjunct procedure.

This paper will be judged for the Resident Writer’s Award.

ABSTRACT

Despite advancements in surgical technique and understanding of throwing mechanics, controversy persists regarding the treatment of grade III acromioclavicular (AC) joint separations, particularly in throwing athletes. Twenty-eight major league baseball (MLB) orthopedic team physicians were surveyed to determine their definitive management of a grade III AC separation in the dominant arm of a professional baseball pitcher and their experience treating AC joint separations in starting pitchers and position players. Return-to-play outcomes were also evaluated. Twenty (71.4%) team physicians recommended nonoperative intervention compared to 8 (28.6%) who would have operated acutely. Eighteen (64.3%) team physicians had treated at least 1 professional pitcher with a grade III AC separation; 51 (77.3%) pitchers had been treated nonoperatively compared to 15 (22.7%) operatively. No difference was observed in the proportion of pitchers who returned to the same level of play (P = .54), had full, unrestricted range of motion (P = .23), or had full pain relief (P = .19) between the operatively and nonoperatively treated MLB pitchers. The majority (53.6%) of physicians would not include an injection if the injury was treated nonoperatively. Open coracoclavicular reconstruction (65.2%) was preferred for operative cases; 66.7% of surgeons would also include distal clavicle excision as an adjunct procedure. About 90% of physicians would return pitchers to throwing >12 weeks after surgery compared to after 4 to 6 weeks in nonoperatively treated cases. In conclusion, MLB team physicians preferred nonoperative management for an acute grade III AC joint separation in professional pitchers. If operative intervention is required, ligament reconstruction with adjunct distal clavicle excision were the most commonly performed procedures.

Continue to: Despite advancements in surgucal technique...

Despite advancements in surgical technique and improved understanding of the physiology of throwing mechanics, controversy persists regarding the preferred treatment for grade III acromioclavicular (AC) joint separations.^1-6 Nonsurgical management has demonstrated return to prior function with fewer complications.⁷ However, there is a growing body of evidence demonstrating that surgical intervention is associated with more favorable outcomes⁸ and should be considered in patients who place high functional demands on their shoulders.⁹

The reported results on professional athletes in the literature remain ambivalent. Multiple small case reports/series have reported successful nonoperative treatment of elite athletes.^10-12 Not surprisingly, McFarland and colleagues¹³ reported in 1997 that 69% of major league baseball (MLB) team physicians preferred nonoperative treatment for a theoretical starting pitcher sustaining a grade III AC separation 1 week prior to the start of the season. In contrast, reports of an inability to throw at a pre-injury level are equally commonplace.^14,15 Nevertheless, all of these studies were limited to small cohorts, as the incidence of grade III AC separations in elite throwing athletes is relatively uncommon.^13,16

In this study, we re-evaluated the study performed by McFarland and colleagues¹³ in 1997 by surveying all active MLB team orthopedic surgeons. We asked them how they would treat a grade III AC separation in a starting professional baseball pitcher. The physicians were also asked about their personal experience evaluating outcomes in these elite athletes. Given our improved understanding of the anatomy, pathophysiology, and surgical techniques for treating grade III AC separations, we hypothesize that more MLB team physicians would favor operative intervention treatment in professional baseball pitchers, as their vocation places higher demands on their shoulders.

MATERIALS AND METHODS

A questionnaire (Appendix A) was distributed to the team physicians of all 30 MLB teams. In addition to surgeon demographics, including age, years in practice, and years of taking care of an MLB team, the initial section of the questionnaire asked orthopedic surgeons how they would treat a theoretical starting pitcher who sustained a grade III AC joint separation of the dominant throwing arm 1 week prior to the start of the season. Physicians who preferred nonoperative treatment were asked whether they would use an injection (and what type), as well as when they would allow the pitcher to start a progressive interval throwing program. Physicians who preferred operative treatment were asked to rank their indications for operating, what procedure they would use (eg, open vs arthroscopic or coracoclavicular ligament repair vs reconstruction), and whether the surgical intervention would include distal clavicle excision. Both groups of physicians were also asked if their preferred treatment would change if the injury were to occur at the end of the season.

The second portion of the questionnaire asked surgeons about their experience treating AC joint separations in both starting pitchers and position players, as well as to describe the long-term outcomes of their preferred treatment, including time to return to full clearance for pitching, whether their patients returned to their prior level of play, and whether these patients had full pain relief. Finally, physicians were asked if any of the nonoperatively treated players ultimately crossed over and required operative intervention.

Continue to: Statistics...

STATISTICS

Descriptive statistics were used for continuous variables, and frequencies were used for categorical variables. Linear regression was performed to determine the correlation between the physician’s training or experience in treating AC joint separations and their recommended treatment. Fischer’s exact test/chi-square analysis was used to compare categorical variables. All tests were conducted using 2-sided hypothesis testing with statistical significance set at P < .05. All statistical analyses were conducted with SPSS 21.0 software (IBM Corporation).

RESULTS

A total of 28 MLB team physicians completed the questionnaires from 18 of the 30 MLB teams. The average age of the responders was 50.5 years (range, 34-60 years), with an average of 18.2 years in practice (range, 2-30 years) and 10.8 years (range, 1-24 years) taking care of their current professional baseball team. About 82% of the team physicians completed a sports medicine fellowship. On average, physicians saw 16.6 (range, 5-50) grade III or higher AC joint separations per year, and operated on 4.6 (range, 0-10) per year.

Nonoperative treatment was the preferred treatment for a grade III AC joint separation in a starting professional baseball pitcher for the majority of team physicians (20/28). No correlation was observed between the physician’s age (P = .881), years in practice (P = .915), years taking care of their professional team (P = .989), percentage of practice focused on shoulders (P = .986), number of AC joint injuries seen (P = .325), or number of surgeries performed per year (P = .807) with the team physician’s preferred treatment. Compared to the proportion reported originally by McFarland and colleagues¹³ in 1997 (69%), there was no difference in the proportion of team physicians that recommended nonoperative treatment (P = 1).

If treating this injury nonoperatively, 46.4% of physicians would also use an injection, with orthobiologics (eg, platelet-rich plasma) as the most popular choice (Table 1). No consensus was provided on the timeframe to return pitchers back to a progressive interval throwing program; however, 46.67% of physicians would return pitchers 4 to 6 weeks after a nonoperatively treated injury, while 35.7% would return pitchers 7 to 12 weeks after the initial injury.

Table 1. Treatment Preferences of Grade III AC Separation by MLB Team Physicians

^aRespondents were allowed to choose more than 1 treatment in each category. ^bChosen as an adjunct treatment.

Abbreviations: AC, acromioclavicular; MLB, major league baseball.

Most physicians (64.3%) cited functional limitations as the most important reason for indicating operative treatment, followed by pain (21.4%), and a deformity (14.3%). About 65% preferred open coracoclavicular ligament reconstruction. No physician recommended the Weaver-Dunn procedure or use of hardware (eg, hook plate). Of those who preferred an operative intervention, 66.7% would also include a distal clavicle excision, which is significantly higher than the proportion reported by McFarland and colleagues¹³ (23%, P = .0170). About 90% of physicians would return pitchers to play >12 weeks after operative treatment.

Continue to: If the injury occurred at the end ...

If the injury occurred at the end of the season, 7 of the 20 orthopedists (35%) who recommended nonoperative treatment said they would change to an operative intervention. Eighteen of 28 responders would have the same algorithm for MLB position players. Team physicians were less likely to recommend operative intervention in position players due to less demand on the arm and increased ability to accommodate the injury by altering their throwing mechanics.

Eighteen (64%) of the team physicians had treated at least 1 professional pitcher with a grade III AC separation in his dominant arm, and 11 (39.3%) had treated >1. Collectively, team physicians had treated 15 professional pitchers operatively, and 51 nonoperatively; only 3 patients converted to operative intervention after a failed nonoperative treatment.

Of the pitchers treated operatively, 93.3% (14) of pitchers returned to their prior level of pitching. The 1 patient who failed to return to the same level of pitching retired instead of returning to play. About 80% (12) of the pitchers had full pain relief, and 93.3% (14) had full range of motion (ROM). The pitcher who failed to regain full ROM also had a concomitant rotator cuff repair. The only complication reported from an operative intervention was a pitcher who sustained a coracoid fracture 10 months postoperatively while throwing 100 mph. Of the pitchers treated nonoperatively, 96% returned to their prior level of pitching, 92.2% (47) had full complete pain relief when throwing, and 100% had full ROM. No differences were observed between the proportion of pitchers who returned to their prior level of pitching, regained full ROM, or had full pain relief in the operative and nonoperative groups (Table 2).

Table 2. Outcomes of Treatment of Grade III AC Separation in 58 Professional Baseball Players

Abbreviations: AC, acromioclavicular; ROM, range of motion.

DISCUSSION 

Controversy persists regarding the optimal management of acute grade III AC separations, with the current available evidence potentially suggesting better cosmetic and radiological results but no definite differences in clinical results.^1-6,17,18 In the absence of formal clinical practice guidelines, surgeons rely on their own experience or defer to the anecdotal experience of experts in the field. Our initial hypothesis was false in this survey of MLB team physicians taking care of overhead throwing athletes at the highest level. Our results demonstrate that despite improved techniques and an increased understanding of the pathophysiology of AC joint separations, conservative management is still the preferred treatment for acute grade III AC joint separations in professional baseball pitchers. The proportion of team physicians recommending nonoperative treatment in our series was essentially equivalent to the results reported by McFarland and colleagues¹³ in 1997, suggesting that the pendulum continues to favor conservative management initially. This status quo likely reflects both the dearth of literature suggesting a substantial benefit of acute operative repair, as well as the ability to accommodate with conservative measures after most grade III AC injuries, even at the highest level of athletic competition.

These results are also consistent with trends from the last few decades. In the 1970s, the overwhelming preference for treating an acute complete AC joint separation was surgical repair, with Powers and Bach¹⁰ reporting in a 1974 survey of 163 chairmen of orthopedic programs around the country that 91.5% advocated surgical treatment. However, surgical preference had reversed by the 1990s. Of the 187 chairmen and 59 team physicians surveyed by Cox¹⁹ in 1992, 72% and 86% respectively preferred nonoperative treatment in a theoretical 21-year-old athlete with a grade III AC separation. Nissen and Chatterjee²⁰ reported in 2007 on a survey of all American Orthopaedic Society for Sports Medicine surgeons (N = 577) and Accreditation Council for Graduate Medical Education orthopedic program residency directors (N = 87) that >80% of responders preferred conservative measures for this acute injury. The reversal of trends has also been corroborated by recent multicenter trials demonstrating no difference in clinical outcomes between operative and nonoperative treatment of high grade AC joint dislocations, albeit these patients were not all high level overhead throwing athletes.^17,18

Continue to: The trends in surgical interventions are notable...

The trends in surgical interventions are notable within the smaller subset of patients who are indicated for operative repair. Use of hardware and primary ligament repair, while popular in the surveys conducted in the 1970s¹⁰ and 1990s¹³ and even present in Nissen and Chatterjee’s²⁰ 2007 survey, were noticeably absent from our survey results, with the majority of respondents preferring open coracoclavicular ligament reconstruction. The role of distal clavicle excision has also expanded, from 23% of team physicians recommending it in 1997¹³ to 57% to 59% in Nissen and Chatterjee’s²⁰ 2007 survey, to 66.7% in our series. This trend is not surprising as several recent cadaveric biomechanical studies have demonstrated that not only do peak graft forces not increase significantly,²¹ the anterior-posterior and superior-inferior motion at the AC joint following ligament reconstruction is maintained despite resection of the lateral clavicle.²² Additionally, primary distal clavicle excision may prevent the development of post-traumatic arthritis at the AC joint and osteolysis of the distal clavicle as a possible pain generator in the future.²³ However, some respondents cautioned against performing a concomitant distal clavicle excision, as some biomechanical data demonstrate that resecting the distal clavicle may lead to increased horizontal translation at the AC joint despite intact superior and posterior AC capsules.²⁴ Professional baseball pitchers may also be more lax and thus prone to more instability. Primary repair or reconstruction may not always lead to complete pre-injury stability in these individuals. This subtle unrecognized instability is hard to diagnosis and may be a persistent source of pain; thus, adding a distal clavicle excision may actually exacerbate the instability.

The nuanced indications for operative intervention, such as the presence of associated lesions were not captured by our survey.²⁵ While most team physicians cited functional limitations as their most common reason for offering surgery, several MLB orthopedic surgeons also commented on evaluating the stability of the AC joint after a grade III injury, akin to the consensus statement from the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) Upper Extremity Committee²⁶ in 2014 that diversified the Rockwood Grade III AC joint separation into its IIIA and IIIB classifications. The ISAKOS recommendations include initial conservative management and a second evaluation (both clinical and radiographic) for grade III lesions 3 to 6 weeks after the injury. However, as professional baseball is an incredibly profitable sport with an annual revenue approaching $9.5 billion²⁷ and pitching salaries up to $32.5 million in 2015, serious financial considerations must be given to players who wish to avoid undergoing delayed surgery.

This study has shortcomings typical of expert opinion papers. The retrospective nature of this study places the data at risk of recall bias. Objective data (eg, terminal ROM, pain relief, and return to play) were obtained from a retrospective chart review; however, no standard documentation or collection method was used given the number of surgeons involved and, thus, conclusions based on treatment outcomes are imperfect. Another major weakness of this survey is the relatively small number of patients and respondents. An a priori power analysis was not available, as this was a retrospective review. A comparative trial will be necessary to definitively support one treatment over another. Assuming a 95% return to play in the nonoperatively treated group, approximately 300 patients would be needed in a prospective 2-armed study with 80% power to detect a 10% reduction in the incidence of return to play using an alpha level of 0.05 and assuming no loss to follow-up. This sample size would be difficult to achieve in this patient population.

However, compared to past series,¹³ the number of professional baseball players treated by the collective experience of these MLB team physicians is the largest reported to date. As suggested above, the rarity of this condition in elite athletes precludes the ability to have matched controls to definitively determine the optimal treatment, which may explain the lack of difference in the return to play, ROM, and pain relief outcomes. Instead, we can only extrapolate based on the collective anecdotal experience of the MLB team physicians.

CONCLUSION

Despite advances in surgical technique and understanding of throwing mechanics, the majority of MLB team physicians preferred nonoperative management for an acute grade III AC joint separation in a professional baseball pitcher. Open coracoclavicular ligament reconstruction was preferred for those who preferred operative intervention. An increasing number of orthopedic surgeons now consider a distal clavicle excision as an adjunct procedure.

This paper will be judged for the Resident Writer’s Award.

ABSTRACT

Despite advancements in surgical technique and understanding of throwing mechanics, controversy persists regarding the treatment of grade III acromioclavicular (AC) joint separations, particularly in throwing athletes. Twenty-eight major league baseball (MLB) orthopedic team physicians were surveyed to determine their definitive management of a grade III AC separation in the dominant arm of a professional baseball pitcher and their experience treating AC joint separations in starting pitchers and position players. Return-to-play outcomes were also evaluated. Twenty (71.4%) team physicians recommended nonoperative intervention compared to 8 (28.6%) who would have operated acutely. Eighteen (64.3%) team physicians had treated at least 1 professional pitcher with a grade III AC separation; 51 (77.3%) pitchers had been treated nonoperatively compared to 15 (22.7%) operatively. No difference was observed in the proportion of pitchers who returned to the same level of play (P = .54), had full, unrestricted range of motion (P = .23), or had full pain relief (P = .19) between the operatively and nonoperatively treated MLB pitchers. The majority (53.6%) of physicians would not include an injection if the injury was treated nonoperatively. Open coracoclavicular reconstruction (65.2%) was preferred for operative cases; 66.7% of surgeons would also include distal clavicle excision as an adjunct procedure. About 90% of physicians would return pitchers to throwing >12 weeks after surgery compared to after 4 to 6 weeks in nonoperatively treated cases. In conclusion, MLB team physicians preferred nonoperative management for an acute grade III AC joint separation in professional pitchers. If operative intervention is required, ligament reconstruction with adjunct distal clavicle excision were the most commonly performed procedures.

Continue to: Despite advancements in surgucal technique...

Despite advancements in surgical technique and improved understanding of the physiology of throwing mechanics, controversy persists regarding the preferred treatment for grade III acromioclavicular (AC) joint separations.^1-6 Nonsurgical management has demonstrated return to prior function with fewer complications.⁷ However, there is a growing body of evidence demonstrating that surgical intervention is associated with more favorable outcomes⁸ and should be considered in patients who place high functional demands on their shoulders.⁹

The reported results on professional athletes in the literature remain ambivalent. Multiple small case reports/series have reported successful nonoperative treatment of elite athletes.^10-12 Not surprisingly, McFarland and colleagues¹³ reported in 1997 that 69% of major league baseball (MLB) team physicians preferred nonoperative treatment for a theoretical starting pitcher sustaining a grade III AC separation 1 week prior to the start of the season. In contrast, reports of an inability to throw at a pre-injury level are equally commonplace.^14,15 Nevertheless, all of these studies were limited to small cohorts, as the incidence of grade III AC separations in elite throwing athletes is relatively uncommon.^13,16

In this study, we re-evaluated the study performed by McFarland and colleagues¹³ in 1997 by surveying all active MLB team orthopedic surgeons. We asked them how they would treat a grade III AC separation in a starting professional baseball pitcher. The physicians were also asked about their personal experience evaluating outcomes in these elite athletes. Given our improved understanding of the anatomy, pathophysiology, and surgical techniques for treating grade III AC separations, we hypothesize that more MLB team physicians would favor operative intervention treatment in professional baseball pitchers, as their vocation places higher demands on their shoulders.

MATERIALS AND METHODS

A questionnaire (Appendix A) was distributed to the team physicians of all 30 MLB teams. In addition to surgeon demographics, including age, years in practice, and years of taking care of an MLB team, the initial section of the questionnaire asked orthopedic surgeons how they would treat a theoretical starting pitcher who sustained a grade III AC joint separation of the dominant throwing arm 1 week prior to the start of the season. Physicians who preferred nonoperative treatment were asked whether they would use an injection (and what type), as well as when they would allow the pitcher to start a progressive interval throwing program. Physicians who preferred operative treatment were asked to rank their indications for operating, what procedure they would use (eg, open vs arthroscopic or coracoclavicular ligament repair vs reconstruction), and whether the surgical intervention would include distal clavicle excision. Both groups of physicians were also asked if their preferred treatment would change if the injury were to occur at the end of the season.

The second portion of the questionnaire asked surgeons about their experience treating AC joint separations in both starting pitchers and position players, as well as to describe the long-term outcomes of their preferred treatment, including time to return to full clearance for pitching, whether their patients returned to their prior level of play, and whether these patients had full pain relief. Finally, physicians were asked if any of the nonoperatively treated players ultimately crossed over and required operative intervention.

Continue to: Statistics...

STATISTICS

Descriptive statistics were used for continuous variables, and frequencies were used for categorical variables. Linear regression was performed to determine the correlation between the physician’s training or experience in treating AC joint separations and their recommended treatment. Fischer’s exact test/chi-square analysis was used to compare categorical variables. All tests were conducted using 2-sided hypothesis testing with statistical significance set at P < .05. All statistical analyses were conducted with SPSS 21.0 software (IBM Corporation).

RESULTS

A total of 28 MLB team physicians completed the questionnaires from 18 of the 30 MLB teams. The average age of the responders was 50.5 years (range, 34-60 years), with an average of 18.2 years in practice (range, 2-30 years) and 10.8 years (range, 1-24 years) taking care of their current professional baseball team. About 82% of the team physicians completed a sports medicine fellowship. On average, physicians saw 16.6 (range, 5-50) grade III or higher AC joint separations per year, and operated on 4.6 (range, 0-10) per year.

Nonoperative treatment was the preferred treatment for a grade III AC joint separation in a starting professional baseball pitcher for the majority of team physicians (20/28). No correlation was observed between the physician’s age (P = .881), years in practice (P = .915), years taking care of their professional team (P = .989), percentage of practice focused on shoulders (P = .986), number of AC joint injuries seen (P = .325), or number of surgeries performed per year (P = .807) with the team physician’s preferred treatment. Compared to the proportion reported originally by McFarland and colleagues¹³ in 1997 (69%), there was no difference in the proportion of team physicians that recommended nonoperative treatment (P = 1).

If treating this injury nonoperatively, 46.4% of physicians would also use an injection, with orthobiologics (eg, platelet-rich plasma) as the most popular choice (Table 1). No consensus was provided on the timeframe to return pitchers back to a progressive interval throwing program; however, 46.67% of physicians would return pitchers 4 to 6 weeks after a nonoperatively treated injury, while 35.7% would return pitchers 7 to 12 weeks after the initial injury.

Table 1. Treatment Preferences of Grade III AC Separation by MLB Team Physicians

^aRespondents were allowed to choose more than 1 treatment in each category. ^bChosen as an adjunct treatment.

Abbreviations: AC, acromioclavicular; MLB, major league baseball.

Most physicians (64.3%) cited functional limitations as the most important reason for indicating operative treatment, followed by pain (21.4%), and a deformity (14.3%). About 65% preferred open coracoclavicular ligament reconstruction. No physician recommended the Weaver-Dunn procedure or use of hardware (eg, hook plate). Of those who preferred an operative intervention, 66.7% would also include a distal clavicle excision, which is significantly higher than the proportion reported by McFarland and colleagues¹³ (23%, P = .0170). About 90% of physicians would return pitchers to play >12 weeks after operative treatment.

Continue to: If the injury occurred at the end ...

If the injury occurred at the end of the season, 7 of the 20 orthopedists (35%) who recommended nonoperative treatment said they would change to an operative intervention. Eighteen of 28 responders would have the same algorithm for MLB position players. Team physicians were less likely to recommend operative intervention in position players due to less demand on the arm and increased ability to accommodate the injury by altering their throwing mechanics.

Eighteen (64%) of the team physicians had treated at least 1 professional pitcher with a grade III AC separation in his dominant arm, and 11 (39.3%) had treated >1. Collectively, team physicians had treated 15 professional pitchers operatively, and 51 nonoperatively; only 3 patients converted to operative intervention after a failed nonoperative treatment.

Of the pitchers treated operatively, 93.3% (14) of pitchers returned to their prior level of pitching. The 1 patient who failed to return to the same level of pitching retired instead of returning to play. About 80% (12) of the pitchers had full pain relief, and 93.3% (14) had full range of motion (ROM). The pitcher who failed to regain full ROM also had a concomitant rotator cuff repair. The only complication reported from an operative intervention was a pitcher who sustained a coracoid fracture 10 months postoperatively while throwing 100 mph. Of the pitchers treated nonoperatively, 96% returned to their prior level of pitching, 92.2% (47) had full complete pain relief when throwing, and 100% had full ROM. No differences were observed between the proportion of pitchers who returned to their prior level of pitching, regained full ROM, or had full pain relief in the operative and nonoperative groups (Table 2).

Table 2. Outcomes of Treatment of Grade III AC Separation in 58 Professional Baseball Players

Abbreviations: AC, acromioclavicular; ROM, range of motion.

DISCUSSION 

Controversy persists regarding the optimal management of acute grade III AC separations, with the current available evidence potentially suggesting better cosmetic and radiological results but no definite differences in clinical results.^1-6,17,18 In the absence of formal clinical practice guidelines, surgeons rely on their own experience or defer to the anecdotal experience of experts in the field. Our initial hypothesis was false in this survey of MLB team physicians taking care of overhead throwing athletes at the highest level. Our results demonstrate that despite improved techniques and an increased understanding of the pathophysiology of AC joint separations, conservative management is still the preferred treatment for acute grade III AC joint separations in professional baseball pitchers. The proportion of team physicians recommending nonoperative treatment in our series was essentially equivalent to the results reported by McFarland and colleagues¹³ in 1997, suggesting that the pendulum continues to favor conservative management initially. This status quo likely reflects both the dearth of literature suggesting a substantial benefit of acute operative repair, as well as the ability to accommodate with conservative measures after most grade III AC injuries, even at the highest level of athletic competition.

These results are also consistent with trends from the last few decades. In the 1970s, the overwhelming preference for treating an acute complete AC joint separation was surgical repair, with Powers and Bach¹⁰ reporting in a 1974 survey of 163 chairmen of orthopedic programs around the country that 91.5% advocated surgical treatment. However, surgical preference had reversed by the 1990s. Of the 187 chairmen and 59 team physicians surveyed by Cox¹⁹ in 1992, 72% and 86% respectively preferred nonoperative treatment in a theoretical 21-year-old athlete with a grade III AC separation. Nissen and Chatterjee²⁰ reported in 2007 on a survey of all American Orthopaedic Society for Sports Medicine surgeons (N = 577) and Accreditation Council for Graduate Medical Education orthopedic program residency directors (N = 87) that >80% of responders preferred conservative measures for this acute injury. The reversal of trends has also been corroborated by recent multicenter trials demonstrating no difference in clinical outcomes between operative and nonoperative treatment of high grade AC joint dislocations, albeit these patients were not all high level overhead throwing athletes.^17,18

Continue to: The trends in surgical interventions are notable...

The trends in surgical interventions are notable within the smaller subset of patients who are indicated for operative repair. Use of hardware and primary ligament repair, while popular in the surveys conducted in the 1970s¹⁰ and 1990s¹³ and even present in Nissen and Chatterjee’s²⁰ 2007 survey, were noticeably absent from our survey results, with the majority of respondents preferring open coracoclavicular ligament reconstruction. The role of distal clavicle excision has also expanded, from 23% of team physicians recommending it in 1997¹³ to 57% to 59% in Nissen and Chatterjee’s²⁰ 2007 survey, to 66.7% in our series. This trend is not surprising as several recent cadaveric biomechanical studies have demonstrated that not only do peak graft forces not increase significantly,²¹ the anterior-posterior and superior-inferior motion at the AC joint following ligament reconstruction is maintained despite resection of the lateral clavicle.²² Additionally, primary distal clavicle excision may prevent the development of post-traumatic arthritis at the AC joint and osteolysis of the distal clavicle as a possible pain generator in the future.²³ However, some respondents cautioned against performing a concomitant distal clavicle excision, as some biomechanical data demonstrate that resecting the distal clavicle may lead to increased horizontal translation at the AC joint despite intact superior and posterior AC capsules.²⁴ Professional baseball pitchers may also be more lax and thus prone to more instability. Primary repair or reconstruction may not always lead to complete pre-injury stability in these individuals. This subtle unrecognized instability is hard to diagnosis and may be a persistent source of pain; thus, adding a distal clavicle excision may actually exacerbate the instability.

The nuanced indications for operative intervention, such as the presence of associated lesions were not captured by our survey.²⁵ While most team physicians cited functional limitations as their most common reason for offering surgery, several MLB orthopedic surgeons also commented on evaluating the stability of the AC joint after a grade III injury, akin to the consensus statement from the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) Upper Extremity Committee²⁶ in 2014 that diversified the Rockwood Grade III AC joint separation into its IIIA and IIIB classifications. The ISAKOS recommendations include initial conservative management and a second evaluation (both clinical and radiographic) for grade III lesions 3 to 6 weeks after the injury. However, as professional baseball is an incredibly profitable sport with an annual revenue approaching $9.5 billion²⁷ and pitching salaries up to $32.5 million in 2015, serious financial considerations must be given to players who wish to avoid undergoing delayed surgery.

This study has shortcomings typical of expert opinion papers. The retrospective nature of this study places the data at risk of recall bias. Objective data (eg, terminal ROM, pain relief, and return to play) were obtained from a retrospective chart review; however, no standard documentation or collection method was used given the number of surgeons involved and, thus, conclusions based on treatment outcomes are imperfect. Another major weakness of this survey is the relatively small number of patients and respondents. An a priori power analysis was not available, as this was a retrospective review. A comparative trial will be necessary to definitively support one treatment over another. Assuming a 95% return to play in the nonoperatively treated group, approximately 300 patients would be needed in a prospective 2-armed study with 80% power to detect a 10% reduction in the incidence of return to play using an alpha level of 0.05 and assuming no loss to follow-up. This sample size would be difficult to achieve in this patient population.

However, compared to past series,¹³ the number of professional baseball players treated by the collective experience of these MLB team physicians is the largest reported to date. As suggested above, the rarity of this condition in elite athletes precludes the ability to have matched controls to definitively determine the optimal treatment, which may explain the lack of difference in the return to play, ROM, and pain relief outcomes. Instead, we can only extrapolate based on the collective anecdotal experience of the MLB team physicians.

CONCLUSION

Despite advances in surgical technique and understanding of throwing mechanics, the majority of MLB team physicians preferred nonoperative management for an acute grade III AC joint separation in a professional baseball pitcher. Open coracoclavicular ligament reconstruction was preferred for those who preferred operative intervention. An increasing number of orthopedic surgeons now consider a distal clavicle excision as an adjunct procedure.

This paper will be judged for the Resident Writer’s Award.

ABSTRACT

Optimal outcomes following total shoulder arthroplasty TSA and reverse shoulder arthroplasty RSA are dependent on proper implant position. Multiple cadaver studies have demonstrated improved accuracy of implant positioning with use of patient-specific guides/instrumentation compared to traditional methods. At this time, there are 3 commercially available single use patient-specific instrumentation systems and 1 commercially available reusable patient-specific instrumentation system. Currently though, there are no studies comparing the clinical outcomes of patient-specific guides to those of traditional methods of glenoid placement, and limited research has been done comparing the accuracy of each system’s 3-dimensional planning software. Future work is necessary to elucidate the ideal indications for the use of patient-specific guides and instrumentation, but it is likely, particularly in the setting of advanced glenoid deformity, that these systems will improve a surgeon's ability to put the implant in the best position possible.

Continue to: Optimal functional recovery...

Optimal functional recovery and implant longevity following both total shoulder arthroplasty (TSA) and reverse shoulder arthroplasty (RSA) depend, in large part, on proper placement of the glenoid component. Glenoid component malpositioning has an adverse effect on shoulder stability, range of motion (ROM), impingement, and glenoid implant longevity.

Traditionally, glenoid component positioning has been done manually by the surgeons based on their review of preoperative films and knowledge of glenoid anatomy. Anatomic studies have demonstrated high individual variability in the version of the native glenoid, thus making ideal placement of the initial glenoid guide pin difficult using standard guide pin guides.¹

The following 2 methods have been described for improving the accuracy of glenoid guide pin insertion and subsequent glenoid implant placement: (1) computerized navigation and (2) patient-specific guides/instrumentation. Although navigated shoulder systems have demonstrated improved accuracy in glenoid placement compared with traditional methods, navigated systems require often large and expensive systems for implementation. The majority of them also require placement of guide pins or arrays on scapular bony landmarks, likely leading to an increase in operative time and possible iatrogenic complications, including fracture and pin site infections.

This review focuses on the use of patient-specific guides/instrumentation in shoulder arthroplasty. This includes the topic of proper glenoid and glenosphere placement as well as patient-specific guides/instrumentation and their accuracy.

GLENOID PLACEMENT

Glenohumeral osteoarthritis is the most common indication for TSA² and commonly results in glenoid deformity. Using computed tomography (CT) scans of 45 arthritic shoulders and 19 normal shoulders, Mullaji and colleagues³ reported that the anteroposterior dimensions of the glenoid were increased by an average of 5 mm to 8 mm in osteoarthritic shoulders and by an average of 6 mm in rheumatoid arthritic shoulders compared to those in normal shoulders. A retrospective review of serial CT scans performed preoperatively on 113 osteoarthritic shoulders by Walch and colleagues⁴ demonstrated an average retroversion of 16°, and it has been the basis for the commonly used Walch classification of glenoid wear in osteoarthritis. Increased glenoid wear and increased glenoid retroversion make the proper restoration of glenoid version, inclination, and offset during shoulder arthroplasty more difficult and lead to increased glenoid component malpositioning.

Continue to: The ideal placement of the glenoid...

The ideal placement of the glenoid to maximize function, ROM, and implant longevity is in a mechanically neutral alignment with no superoinferior inclination¹ and neutral version with respect to the transverse axis of the scapula.⁵

Improper glenoid positioning has an adverse effect on the functional results of shoulder arthroplasty. Yian and colleagues⁶ evaluated 47 cemented, pegged glenoids using standard radiography and CT scans at a mean follow-up of 40 months. They observed a significant correlation between increased glenoid component retroversion and lower Constant scores. Hasan and colleagues⁷ evaluated 139 consecutive patients who were dissatisfied with the result of their primary arthroplasty and found that 28% of them had at least 1 substantially malpositioned component identified either on radiography or during a revision surgery. They also found a significant correlation between stiffness, instability, and component malposition in their cohort.

Glenoid longevity is also dependent on proper component positioning, with the worst outcomes coming if the glenoid is malaligned with either superior or inferior inclination. Hasan and colleagues⁷ found that of their 74 patients with failed TSAs, 44 patients (59%) demonstrated mechanical loosening of their glenoid components either radiographically or during revision surgery, and 10 of their 44 patients with loose glenoids (23%) also had a malpositioned component. Using finite element analysis, Hopkins and colleagues⁸ analyzed the stresses through the cement mantle in glenoid prostheses that were centrally aligned, superiorly inclined, inferiorly inclined, anteverted, and retroverted. They found that malalignment of the glenoid increases the stresses through the cement mantle, leading to increased likelihood of mantle failure compared to that of centrally aligned glenoids, especially if there is malalignment with superior or inferior inclination or retroversion.

The accuracy of traditional methods of glenoid placement using an initial guide pin is limited and decreases with increasing amounts of glenoid deformity and retroversion. Iannotti and colleagues ⁹ investigated 13 patients undergoing TSA with an average preoperative retroversion of 13° and evaluated them using a 3-dimensional (3-D) surgical simulator. They found that the postoperative glenoid version was within 5° of ideal version in only 7 of their 13 patients (54%) and within 10° of ideal version in only 10 of their 13 patients (77%). In their study, the ideal version was considered to be the version as close to perpendicular to the plane of the scapula as possible with complete contact of the back side of the component on glenoid bone and maintenance of the center peg of the component within bone. In addition, they found that of their 7 patients with preoperative retroversion >10°, only 1 patient (14%) had a postoperative glenoid with <10° of retroversion with regard to the plane of the scapula and that all 6 of their patients with preoperative glenoid retroversion of <10° had a postoperative glenoid version of <10°.

Preoperative CT scans are much more accurate at determining glenoid version and thus how much glenoid correction is required to reestablish neutral version than plain radiography. Nyffeler and colleagues¹⁰ compared CT scans with axillary views for comparing glenoid version in 25 patients with no shoulder prosthesis present and 25 patients with a TSA in place. They found that glenoid retroversion was overestimated on plain radiographs in 86% of their patients with an average difference between CT and plain radiography of 6.4° and a maximum difference of 21°. They also found poor interobserver reliability in the plain radiography group and good interobserver reliability in the CT group, with coefficients of correlation of 0.77 for the plain radiography group and 0.93 for the CT group. Thus, they concluded that glenoid version cannot be accurately measured by plain radiography and that CT should be used. Hoenecke and colleagues¹¹ subsequently evaluated 33 patients scheduled for TSA and found that CT version measurements made on 2-dimensional (2-D) CT slices compared with 3-D-reconstructed models of the same CT slices differed by an average of 5.1° because the axial CT slices were most often made perpendicular to the axis of the patient’s torso and not perpendicular to the body of the scapula. Accurate version assessment is critically important in planning for the degree of correction required to restore neutral glenoid version, and differences of 6.4° between CT assessment and plain radiography, and 5.1° between 2-D and 3-D CT scan assessments may lead to inadequate version correction intraoperatively and inferior postoperative results.

Continue to: GLENOSPHERE PLACEMENT

The most common indication for reverse TSA is rotator cuff arthropathy characterized by rotator cuff dysfunction and end-stage glenohumeral arthritis.¹² These patients require accurate and reproducible glenoid placement to optimize their postoperative range of motion and stability and minimize scapular notching.

Ideal glenosphere placement is the location and orientation that maximizes impingement-free ROM and stability while avoiding notching. Individual patient anatomy determines ideal placement; however, several guidelines for placement include inferior translation on the glenoid with neutral to inferior inclination. Gutiérrez and colleagues¹³ developed a computer model to assess the hierarchy of surgical factors affecting the ROM after a reverse TSA. They found that lateralizing the center of rotation gave the largest increase in impingement-free abduction, followed closely by inferior translation of the glenosphere on the glenoid.

Avoiding scapular notching is also a very important factor in ideal glenosphere placement. Scapular notching can be described as impingement of the humeral cup against the scapular neck during arm adduction and/or humeral rotation. Gutiérrez and colleagues¹³ also found that decreasing the neck shaft angle to create a more varus proximal humerus was the most important factor in increasing the impingement-free adduction. Roche and colleagues¹⁴ reviewed the radiographs of 151 patients who underwent primary reverse TSA at a mean follow-up of 28.3 months postoperatively; they found that 13.2% of their patients had a notch and that, on average, their patients who had no scapular notch had significantly more inferior glenosphere overhang than those who had a scapular notch. Poon and colleagues¹⁵ found that a glenosphere overhang of >3.5 mm prevented notching in their randomized control trial comparing concentrically and eccentrically placed glenospheres. Multiple other studies have demonstrated similar results and recommended inferior glenoid translation and inferior glenoid inclination to avoid scapular notching.^16,17 Lévigne and colleagues¹⁸ retrospectively reviewed 337 reverse TSAs and observed a correlation between scapular notching and radiolucencies around the glenosphere component, with 14% of patients with scapular notching displaying radiolucencies vs 4% of patients without scapula notching displaying radiolucencies.

Several studies have also focused on the ideal amount of inferior glenoid inclination to maximize impingement-free ROM. Li and colleagues¹⁷ performed a computer simulation study on the Comprehensive Reverse Shoulder System (Zimmer Biomet) to determine impingement-free internal and external ROM with varying amounts of glenosphere offset, translation, and inclination. They found that progressive glenosphere inferior inclination up to 30° improved impingement-free rotational ROM at all degrees of scaption. Gutiérrez and colleagues¹⁹ used computer modeling to compare concentrically placed glenospheres in neutral inclination with eccentrically placed glenospheres in varying degrees of inclination. They found that the lowest forces across the baseplate occurred in the lateralized and inferiorly inclined glenospheres, and the highest forces occurred in the lateralized and superiorly inclined glenospheres. Together, these studies show that inferior glenoid inclination increases impingement-free ROM and, combined with lateralization, may result in improved glenosphere longevity due to significantly decreased forces at the RSA glenoid baseplate when compared to that at superiorly inclined glenoids.

The ideal amount of mediolateral glenosphere offset has not been well defined. Grammont design systems place the center of rotation of the glenosphere medial to the glenoid baseplate together with valgus humeral component neck shaft angles of around 155°. These design elements are believed to decrease shear stresses through the glenoid baseplate to the glenoid interface and improve shoulder stability, but they are also associated with reduced impingement-free ROM and increased rates of scapular notching.¹³ This effect is accentuated in patients with preexisting glenoid bone loss and/or congenitally short scapular necks that further medialize the glenosphere. Medialization of the glenosphere may also shorten the remaining rotator cuff muscles and result in decreased implant stability and external rotation strength. Several implant systems have options to vary the amount of lateral offset. The correct amount of lateral offset for each patient requires the understanding that improving patients’ impingement-free ROM by increasing the amount of lateral offset comes at the price of increasing the shear forces experienced by the interface between the glenoid baseplate and the glenoid. As glenoid fixation technology improves increased lateralization of glenospheres without increased rates of glenoid baseplate, loosening should improve the ROM after reverse TSA.

Continue to: Regardless of the intraoperative goals...

Regardless of the intraoperative goals for placement and orientation of the glenosphere components, it is vitally important to accurately and consistently meet those goals for achieving optimal patient outcomes. Verborgt and colleagues²⁰ implanted 7 glenospheres in cadaveric specimens without any glenohumeral arthritis using standard techniques to evaluate the accuracy of glenosphere version and inclination. Their goal was to place components in neutral version and with 10° of inferior inclination. Their average glenoid version postoperatively was 8.7° of anteversion, and their average inclination was 0.9° of superior inclination. Throckmorton and colleagues²¹ randomized 35 cadaveric shoulders to receive either an anatomic or a reverse total shoulder prosthesis from high-, mid-, and low-volume surgeons. They found that components placed using traditional guides averaged 6° of deviation in version and 5° of deviation in inclination from their target values, with no significant differences between surgeons of different volumes.

PATIENT-SPECIFIC GUIDES/INSTRUMENTATION

Patient-specific guides/instrumentation and intraoperative navigation are the 2 techniques that have been used to improve the accuracy of glenoid and glenosphere placement. Both techniques require the use of high-resolution CT scans and computer software to determine the proper position for glenoid or glenosphere placement based on the patient’s individual anatomy. Patient-specific guides and instrumentation use the data acquired from a CT scan to generate a preoperative plan for the location and orientation of the glenoid baseplate. Once the surgeon approves the preoperative plan, a patient-specific guide is created using the patient’s glenoid as a reference for the location and orientation of the central guide pin. The location of the central guide pin on the glenoid determines the center of the glenoid baseplate, and the guide pin’s orientation determines the version and inclination of the glenoid or the glenosphere. Once the guide pin is placed in the glenoid, the remainder of the glenoid implantation uses the guide pin as a reference, and, in that way, patient-specific guides control the orientation of the glenoid at the time of surgery.

Intraoperative navigation uses an optical tracking system to determine the location and orientation of the central guide pin. Navigation systems require intraoperative calibration of the optical tracking system before they can track the location of implantation relative to bony landmarks on the patient’s scapula. Their advantage over patient-specific instrumentation (PSI) is that they do not require the manufacture of a custom guide; however, they may add significantly increased cost and surgical time due to the need for calibration prior to use and the cost of the navigation system along with any disposable components associated with it. Kircher and colleagues²² performed a prospective randomized clinical study of navigation-aided TSA compared with conventional TSA and found that operating time was significantly increased for the navigated group with an average operating room time of 169.5 minutes compared to 138 minutes for the conventional group. They also found that navigation had to be abandoned in 37.5% of their navigated patients due to technical errors during glenoid referencing.

COMMERCIAL PATIENT-SPECIFIC INSTRUMENTATION SYSTEMS

The 2 types of PSI that are currently available are single-use PSI and reusable PSI. The single-use PSI involves the fabrication of unique guides based on surgeon-approved preoperative plans generated by computer-software-processed preoperative CT scans. The guides are fabricated to rest on the glenoid articular surface and direct the guide pin to the correct location and in the correct direction to place the glenoid baseplate in the desired position with the desired version and inclination. Most of these systems also provide a 3-D model of the patient’s glenoid so that surgeons can visualize glenoid deformities and the correct guide placement on the glenoid. Single-use PSI systems are available from DJO Global, Wright Medical Group, and Zimmer Biomet. The second category of PSI is reusable and is available from Arthrex. The guide pin for this system is adjusted to fit individual patient anatomy and guide the guide pin into the glenoid in a location and orientation preplanned on the CT-scan-based computer software or using a 3-D model of the patient’s glenoid (Table).

Table. Details of Available Patient-Specific Instrumentation Systems

The DJO Global patient-specific guide is termed as the MatchPoint System. This system creates 3-D renderings of the scapula and allows the surgeon to manipulate the glenoid baseplate on the scapula. The surgeon chooses the glenoid baseplate, location, version, and inclination on the computerized 3-D model. The system then fabricates a guide pin matching the computerized template that references the patient’s glenoid surface with a hook to orient it against the coracoid. A 3-D model of the glenoid is also provided along with the customized guide pin.

Continue to: Blueprint 3D Planning + PSI...

Blueprint 3D Planning + PSI (Wright Medical Group) allows custom placement of the glenoid version, inclination, and position on computerized 3-D models of the patient’s scapula. This PSI references the glenoid with 4 feet that captures the edge of the patient’s glenoid at specific locations and is unique because it allows the surgeon to control where on the glenoid edge to 4 feet contact as long as 1 foot is placed on the posterior edge of the glenoid and the remaining 3 feet are placed on the anterior edge of the glenoid. A 3-D model of the glenoid is also provided with this guide.

The Zimmer Biomet patient-specific guide is termed as the Zimmer Patient Specific Instruments Shoulder. Its computer software allows custom placement of the glenoid as well, but it also includes computerized customization of the reaming depth, screw angles, and screw lengths to optimize fixation. Their system includes a central guide pin to set the glenoid baseplate’s location and orientation, a reaming guide to control reaming depth and direction, a roll guide to control the glenoid baseplate’s rotation, and a drill guide to control the screw direction. They also provide a 3-D model of the glenoid.

The Arthrex Virtual Implant Positioning (VIP) System is similar to other systems in that its 3-D planning software is based on CT images uploaded by the surgeon. The unique aspect of this system is that the guide pin is adjusted by the surgeon for each individual patient based on instructions generated by the planning software; however, after use, the instruments are resterilized and reused on subsequent patients (Figures 1A, 1B). In this manner, their instruments are reusable and allow custom adjustment for each patient with the ability to set the pin location and glenoid version in a patient-specific manner. This has the potential benefit of keeping costs down. For more complex deformity cases, the Arthrex VIP System can also 3-D-print a sterile model of the glenoid to help surgeons appreciate the deformity better (Figure 2).

DATA ON PATIENT-SPECIFIC INSTRUMENTS

Several studies have measured the accuracy of patient-specific guides and have compared the accuracy of patient-specific guides to that of traditional methods. Levy and colleagues²³ investigated the accuracy of single-use patient-specific guides compared to that of preoperative plans. They used patient-specific guides on 14 cadaveric shoulders based on plans developed by virtual preoperative 3-D planning system using CT images. Once the guide pin was drilled using the patient-specific guide, they obtained a second CT scan to compare the accuracy of the patient-specific guide to the surgical plan generated preoperatively. They found that the translational accuracy of the starting point for the guide pin averaged 1.2 mm ± 0.7 mm, the accuracy of the inferior inclination was 1.2° ± 1.2°, and the accuracy of the glenoid version was 2.6° ± 1.7°. They concluded that patient-specific guides were highly accurate in reproducing the starting point, inclination, and version set on preoperative guides.

Walch and colleagues²⁴ subsequently performed a similar study using 15 cadaveric scapulae without any other shoulder soft tissue or bone attached. They also used CT-scan-based 3-D planning software to plan their glenoid placement with a subsequently fabricated single-use patient-specific guide used to place a guide pin. They obtained a second CT scan after guide pin implantation and compared the preoperative plan with the subsequent guide pin. They found a mean entry point position error of 1.05 mm ± 0.31 mm, a mean inclination error of 1.42° ± 1.37°, and a mean version error of 1.64° ± 1.01°.

Continue to: Throckmorton and colleagues...

Throckmorton and colleagues²¹ used 70 cadaveric shoulders with radiographically confirmed arthritis and randomized them to undergo either anatomic or reverse TSA using either a patient-specific guide or standard instrumentation. Postoperative CT scans were used to evaluate the glenoid inclination, version, and starting point. They found that glenoid components implanted using patient-specific guides were more accurate than those placed using traditional instrumentation. The average deviation from intended inclination was 3° for patient-specific guides and 7° for traditional instrumentation, the average deviation from intended version was 5° for patient-specific guides and 8° for traditional instrumentation, and the average deviation in intended starting point was 2 mm for patient-specific guides and 3 mm for traditional instrumentation. They also analyzed significantly malpositioned components as defined by a variation in version or inclination of >10° or >4 mm in starting point. They found that 6 of their 35 glenoids using patient-specific guides were significantly malpositioned compared to 23 of 35 glenoids using traditional instrumentation. They concluded that patient-specific guides were more accurate and reduced the number of significantly malpositioned implants when compared with traditional instrumentation.

Early and colleagues²⁵ analyzed the effect of severe glenoid bone defects on the accuracy of patient-specific guides compared with traditional guides. Using 10 cadaveric shoulders, they created anterior, central, or posterior glenoid defects using a reamer and chisel to erode the bone past the coracoid base. Subsequent CT scans were performed on the specimens, and patient-specific guides were fabricated and used for reverse TSA in 5 of the 10 specimens. A reverse TSA was performed using traditional instrumentation in the remaining 5 specimens. They found that the average deviation in inclination and version from preoperative plan was more accurate in the patient-specific guide cohort than that in the traditional instrument cohort, with an average deviation in inclination and version of 1.2° ± 1.2° and 1.8° ± 1.2° respectively for the cohort using patient-specific instruments vs 2.8° ± 1.8° and 3.5° ± 3° for the cohort using traditional instruments. They also found that their total bone screw lengths were longer in the patient-specific guide group than those in the traditional group, with screws averaging 52% of preoperatively planned length in the traditional instrument cohort vs 89% of preoperatively planned length in the patient-specific instrument cohort.

Gauci and colleagues²⁶ measured the accuracy of patient-specific guides in vivo in 17 patients receiving TSA. Preoperative CT scans were used to fabricate patient-specific guides, and postoperative CT scans were used to measure version, inclination, and error of entry in comparison with the templated goals used to create patient-specific guides. They found a mean error in version and inclination of 3.4° and 1.8°, respectively, and a mean error in entry of 0.9 mm of translation on the glenoid. Dallalana and colleagues²⁷ performed a very similar study on 20 patients and found a mean deviation in glenoid version of 1.8° ± 1.9°, a mean deviation in glenoid inclination of 1.3° ± 1.0°, a mean translation in anterior-posterior plane of 0.5 mm ± 0.3 mm, and a mean translation in the superior-inferior plane of 0.8 mm ± 0.5 mm.

Hendel and colleagues²⁸ performed a randomized prospective clinical trial comparing patient-specific guides with traditional methods for glenoid insertion. They randomized 31 patients to receive a glenoid implant using either a patient-specific guide or traditional methods and compared glenoid retroversion and inclination with their preoperative plan. They found an average version deviation of 6.9° in the traditional method cohort and 4.3° in the patient-specific guide cohort. Their average deviation in inclination was 11.6° in the traditional method cohort and 2.9° in the patient-specific guide cohort. For patients with preoperative retroversion >16°, the average deviation was 10° in the standard surgical cohort and 1.2° in the patient-specific instrument cohort. Their data suggest that increasing preoperative retroversion leads to an increased version variation from preoperative plan.

Iannotti and colleagues²⁹ randomly assigned 46 patients to preoperatively undergo either CT scan with 3-D templating of glenoid component without patient-specific guide fabrication or CT scan with 3-D templating and patient-specific guide fabrication prior to receiving a TSA. They recorded the postoperative inclination and version for each patient and compared them to those of a nonrandomized control group of 17 patients who underwent TSA using standard instrumentation. They found no difference between the cohorts with or without patient-specific guide use with regard to implant location, inclination, or version; however, they did find a difference between the combined 3-D templating cohort compared with their standard instrumentation cohort. They concluded that 3-D templating significantly improved the surgeons’ ability to correctly position the glenoid component with or without the fabrication and the use of a patient-specific guide.

Continue to: Denard and colleagues...

Denard and colleagues³⁰ compared the preoperative glenoid version and inclination measurements obtained using the Blueprint 3D Planning + PSI software and the VIP System 3D planning software. They analyzed the preoperative CT scans of 63 consecutive patients undergoing either TSA or reverse TSA using both the Blueprint and the VIP System 3D planning software and compared the resulting native glenoid version and inclination measured by the software. They found a statistically significant difference (P = 0.04) in the version measurements provided by the different planning software; however, the differences found in inclination did not reach statistical significance (P = 0.463). In 19 of the 63 patients (30%), the version measurements between the systems were >5°, and in 29 of the 63 patients (46%), the inclination measurements between the systems were 5° or greater. In addition, 12 of the 63 patients (19%) had both version and inclination measurement differences of >5° between the systems. In total, they found that 35 of the 63 patients had at least 1 measurement that varied by >5° between the systems, and that in 15 patients (24%), 1 measurement varied by >10°. Their data demonstrate considerable variability in the preoperative measurements provided by different 3-D planning software systems, and that further study of each commercially available 3-D planning software system is needed to evaluate their accuracy.

CONCLUSION

Optimal outcomes following TSA and reverse TSA are dependent on proper implant position. Multiple studies have demonstrated improved accuracy in implant positioning with the use of patient-specific guides compared to that with traditional methods. Currently, there are no studies comparing the clinical outcomes of patient-specific guides to those of traditional methods of glenoid placement, and limited research had been done comparing the accuracy of each system’s 3-D planning software with each other and with standardized measurements of glenoid version and inclination. Further research is required to determine the accuracy of each commercially available 3-D planning software system as well as the clinical benefit of patient-specific guides in shoulder arthroplasty.

ABSTRACT

Optimal outcomes following total shoulder arthroplasty TSA and reverse shoulder arthroplasty RSA are dependent on proper implant position. Multiple cadaver studies have demonstrated improved accuracy of implant positioning with use of patient-specific guides/instrumentation compared to traditional methods. At this time, there are 3 commercially available single use patient-specific instrumentation systems and 1 commercially available reusable patient-specific instrumentation system. Currently though, there are no studies comparing the clinical outcomes of patient-specific guides to those of traditional methods of glenoid placement, and limited research has been done comparing the accuracy of each system’s 3-dimensional planning software. Future work is necessary to elucidate the ideal indications for the use of patient-specific guides and instrumentation, but it is likely, particularly in the setting of advanced glenoid deformity, that these systems will improve a surgeon's ability to put the implant in the best position possible.

Continue to: Optimal functional recovery...

Optimal functional recovery and implant longevity following both total shoulder arthroplasty (TSA) and reverse shoulder arthroplasty (RSA) depend, in large part, on proper placement of the glenoid component. Glenoid component malpositioning has an adverse effect on shoulder stability, range of motion (ROM), impingement, and glenoid implant longevity.

Traditionally, glenoid component positioning has been done manually by the surgeons based on their review of preoperative films and knowledge of glenoid anatomy. Anatomic studies have demonstrated high individual variability in the version of the native glenoid, thus making ideal placement of the initial glenoid guide pin difficult using standard guide pin guides.¹

The following 2 methods have been described for improving the accuracy of glenoid guide pin insertion and subsequent glenoid implant placement: (1) computerized navigation and (2) patient-specific guides/instrumentation. Although navigated shoulder systems have demonstrated improved accuracy in glenoid placement compared with traditional methods, navigated systems require often large and expensive systems for implementation. The majority of them also require placement of guide pins or arrays on scapular bony landmarks, likely leading to an increase in operative time and possible iatrogenic complications, including fracture and pin site infections.

This review focuses on the use of patient-specific guides/instrumentation in shoulder arthroplasty. This includes the topic of proper glenoid and glenosphere placement as well as patient-specific guides/instrumentation and their accuracy.

GLENOID PLACEMENT

Glenohumeral osteoarthritis is the most common indication for TSA² and commonly results in glenoid deformity. Using computed tomography (CT) scans of 45 arthritic shoulders and 19 normal shoulders, Mullaji and colleagues³ reported that the anteroposterior dimensions of the glenoid were increased by an average of 5 mm to 8 mm in osteoarthritic shoulders and by an average of 6 mm in rheumatoid arthritic shoulders compared to those in normal shoulders. A retrospective review of serial CT scans performed preoperatively on 113 osteoarthritic shoulders by Walch and colleagues⁴ demonstrated an average retroversion of 16°, and it has been the basis for the commonly used Walch classification of glenoid wear in osteoarthritis. Increased glenoid wear and increased glenoid retroversion make the proper restoration of glenoid version, inclination, and offset during shoulder arthroplasty more difficult and lead to increased glenoid component malpositioning.

Continue to: The ideal placement of the glenoid...

The ideal placement of the glenoid to maximize function, ROM, and implant longevity is in a mechanically neutral alignment with no superoinferior inclination¹ and neutral version with respect to the transverse axis of the scapula.⁵

Improper glenoid positioning has an adverse effect on the functional results of shoulder arthroplasty. Yian and colleagues⁶ evaluated 47 cemented, pegged glenoids using standard radiography and CT scans at a mean follow-up of 40 months. They observed a significant correlation between increased glenoid component retroversion and lower Constant scores. Hasan and colleagues⁷ evaluated 139 consecutive patients who were dissatisfied with the result of their primary arthroplasty and found that 28% of them had at least 1 substantially malpositioned component identified either on radiography or during a revision surgery. They also found a significant correlation between stiffness, instability, and component malposition in their cohort.

Glenoid longevity is also dependent on proper component positioning, with the worst outcomes coming if the glenoid is malaligned with either superior or inferior inclination. Hasan and colleagues⁷ found that of their 74 patients with failed TSAs, 44 patients (59%) demonstrated mechanical loosening of their glenoid components either radiographically or during revision surgery, and 10 of their 44 patients with loose glenoids (23%) also had a malpositioned component. Using finite element analysis, Hopkins and colleagues⁸ analyzed the stresses through the cement mantle in glenoid prostheses that were centrally aligned, superiorly inclined, inferiorly inclined, anteverted, and retroverted. They found that malalignment of the glenoid increases the stresses through the cement mantle, leading to increased likelihood of mantle failure compared to that of centrally aligned glenoids, especially if there is malalignment with superior or inferior inclination or retroversion.

The accuracy of traditional methods of glenoid placement using an initial guide pin is limited and decreases with increasing amounts of glenoid deformity and retroversion. Iannotti and colleagues ⁹ investigated 13 patients undergoing TSA with an average preoperative retroversion of 13° and evaluated them using a 3-dimensional (3-D) surgical simulator. They found that the postoperative glenoid version was within 5° of ideal version in only 7 of their 13 patients (54%) and within 10° of ideal version in only 10 of their 13 patients (77%). In their study, the ideal version was considered to be the version as close to perpendicular to the plane of the scapula as possible with complete contact of the back side of the component on glenoid bone and maintenance of the center peg of the component within bone. In addition, they found that of their 7 patients with preoperative retroversion >10°, only 1 patient (14%) had a postoperative glenoid with <10° of retroversion with regard to the plane of the scapula and that all 6 of their patients with preoperative glenoid retroversion of <10° had a postoperative glenoid version of <10°.

Preoperative CT scans are much more accurate at determining glenoid version and thus how much glenoid correction is required to reestablish neutral version than plain radiography. Nyffeler and colleagues¹⁰ compared CT scans with axillary views for comparing glenoid version in 25 patients with no shoulder prosthesis present and 25 patients with a TSA in place. They found that glenoid retroversion was overestimated on plain radiographs in 86% of their patients with an average difference between CT and plain radiography of 6.4° and a maximum difference of 21°. They also found poor interobserver reliability in the plain radiography group and good interobserver reliability in the CT group, with coefficients of correlation of 0.77 for the plain radiography group and 0.93 for the CT group. Thus, they concluded that glenoid version cannot be accurately measured by plain radiography and that CT should be used. Hoenecke and colleagues¹¹ subsequently evaluated 33 patients scheduled for TSA and found that CT version measurements made on 2-dimensional (2-D) CT slices compared with 3-D-reconstructed models of the same CT slices differed by an average of 5.1° because the axial CT slices were most often made perpendicular to the axis of the patient’s torso and not perpendicular to the body of the scapula. Accurate version assessment is critically important in planning for the degree of correction required to restore neutral glenoid version, and differences of 6.4° between CT assessment and plain radiography, and 5.1° between 2-D and 3-D CT scan assessments may lead to inadequate version correction intraoperatively and inferior postoperative results.

Continue to: GLENOSPHERE PLACEMENT

The most common indication for reverse TSA is rotator cuff arthropathy characterized by rotator cuff dysfunction and end-stage glenohumeral arthritis.¹² These patients require accurate and reproducible glenoid placement to optimize their postoperative range of motion and stability and minimize scapular notching.

Ideal glenosphere placement is the location and orientation that maximizes impingement-free ROM and stability while avoiding notching. Individual patient anatomy determines ideal placement; however, several guidelines for placement include inferior translation on the glenoid with neutral to inferior inclination. Gutiérrez and colleagues¹³ developed a computer model to assess the hierarchy of surgical factors affecting the ROM after a reverse TSA. They found that lateralizing the center of rotation gave the largest increase in impingement-free abduction, followed closely by inferior translation of the glenosphere on the glenoid.

Avoiding scapular notching is also a very important factor in ideal glenosphere placement. Scapular notching can be described as impingement of the humeral cup against the scapular neck during arm adduction and/or humeral rotation. Gutiérrez and colleagues¹³ also found that decreasing the neck shaft angle to create a more varus proximal humerus was the most important factor in increasing the impingement-free adduction. Roche and colleagues¹⁴ reviewed the radiographs of 151 patients who underwent primary reverse TSA at a mean follow-up of 28.3 months postoperatively; they found that 13.2% of their patients had a notch and that, on average, their patients who had no scapular notch had significantly more inferior glenosphere overhang than those who had a scapular notch. Poon and colleagues¹⁵ found that a glenosphere overhang of >3.5 mm prevented notching in their randomized control trial comparing concentrically and eccentrically placed glenospheres. Multiple other studies have demonstrated similar results and recommended inferior glenoid translation and inferior glenoid inclination to avoid scapular notching.^16,17 Lévigne and colleagues¹⁸ retrospectively reviewed 337 reverse TSAs and observed a correlation between scapular notching and radiolucencies around the glenosphere component, with 14% of patients with scapular notching displaying radiolucencies vs 4% of patients without scapula notching displaying radiolucencies.

Several studies have also focused on the ideal amount of inferior glenoid inclination to maximize impingement-free ROM. Li and colleagues¹⁷ performed a computer simulation study on the Comprehensive Reverse Shoulder System (Zimmer Biomet) to determine impingement-free internal and external ROM with varying amounts of glenosphere offset, translation, and inclination. They found that progressive glenosphere inferior inclination up to 30° improved impingement-free rotational ROM at all degrees of scaption. Gutiérrez and colleagues¹⁹ used computer modeling to compare concentrically placed glenospheres in neutral inclination with eccentrically placed glenospheres in varying degrees of inclination. They found that the lowest forces across the baseplate occurred in the lateralized and inferiorly inclined glenospheres, and the highest forces occurred in the lateralized and superiorly inclined glenospheres. Together, these studies show that inferior glenoid inclination increases impingement-free ROM and, combined with lateralization, may result in improved glenosphere longevity due to significantly decreased forces at the RSA glenoid baseplate when compared to that at superiorly inclined glenoids.

The ideal amount of mediolateral glenosphere offset has not been well defined. Grammont design systems place the center of rotation of the glenosphere medial to the glenoid baseplate together with valgus humeral component neck shaft angles of around 155°. These design elements are believed to decrease shear stresses through the glenoid baseplate to the glenoid interface and improve shoulder stability, but they are also associated with reduced impingement-free ROM and increased rates of scapular notching.¹³ This effect is accentuated in patients with preexisting glenoid bone loss and/or congenitally short scapular necks that further medialize the glenosphere. Medialization of the glenosphere may also shorten the remaining rotator cuff muscles and result in decreased implant stability and external rotation strength. Several implant systems have options to vary the amount of lateral offset. The correct amount of lateral offset for each patient requires the understanding that improving patients’ impingement-free ROM by increasing the amount of lateral offset comes at the price of increasing the shear forces experienced by the interface between the glenoid baseplate and the glenoid. As glenoid fixation technology improves increased lateralization of glenospheres without increased rates of glenoid baseplate, loosening should improve the ROM after reverse TSA.

Continue to: Regardless of the intraoperative goals...

Regardless of the intraoperative goals for placement and orientation of the glenosphere components, it is vitally important to accurately and consistently meet those goals for achieving optimal patient outcomes. Verborgt and colleagues²⁰ implanted 7 glenospheres in cadaveric specimens without any glenohumeral arthritis using standard techniques to evaluate the accuracy of glenosphere version and inclination. Their goal was to place components in neutral version and with 10° of inferior inclination. Their average glenoid version postoperatively was 8.7° of anteversion, and their average inclination was 0.9° of superior inclination. Throckmorton and colleagues²¹ randomized 35 cadaveric shoulders to receive either an anatomic or a reverse total shoulder prosthesis from high-, mid-, and low-volume surgeons. They found that components placed using traditional guides averaged 6° of deviation in version and 5° of deviation in inclination from their target values, with no significant differences between surgeons of different volumes.

PATIENT-SPECIFIC GUIDES/INSTRUMENTATION

Patient-specific guides/instrumentation and intraoperative navigation are the 2 techniques that have been used to improve the accuracy of glenoid and glenosphere placement. Both techniques require the use of high-resolution CT scans and computer software to determine the proper position for glenoid or glenosphere placement based on the patient’s individual anatomy. Patient-specific guides and instrumentation use the data acquired from a CT scan to generate a preoperative plan for the location and orientation of the glenoid baseplate. Once the surgeon approves the preoperative plan, a patient-specific guide is created using the patient’s glenoid as a reference for the location and orientation of the central guide pin. The location of the central guide pin on the glenoid determines the center of the glenoid baseplate, and the guide pin’s orientation determines the version and inclination of the glenoid or the glenosphere. Once the guide pin is placed in the glenoid, the remainder of the glenoid implantation uses the guide pin as a reference, and, in that way, patient-specific guides control the orientation of the glenoid at the time of surgery.

Intraoperative navigation uses an optical tracking system to determine the location and orientation of the central guide pin. Navigation systems require intraoperative calibration of the optical tracking system before they can track the location of implantation relative to bony landmarks on the patient’s scapula. Their advantage over patient-specific instrumentation (PSI) is that they do not require the manufacture of a custom guide; however, they may add significantly increased cost and surgical time due to the need for calibration prior to use and the cost of the navigation system along with any disposable components associated with it. Kircher and colleagues²² performed a prospective randomized clinical study of navigation-aided TSA compared with conventional TSA and found that operating time was significantly increased for the navigated group with an average operating room time of 169.5 minutes compared to 138 minutes for the conventional group. They also found that navigation had to be abandoned in 37.5% of their navigated patients due to technical errors during glenoid referencing.

COMMERCIAL PATIENT-SPECIFIC INSTRUMENTATION SYSTEMS

The 2 types of PSI that are currently available are single-use PSI and reusable PSI. The single-use PSI involves the fabrication of unique guides based on surgeon-approved preoperative plans generated by computer-software-processed preoperative CT scans. The guides are fabricated to rest on the glenoid articular surface and direct the guide pin to the correct location and in the correct direction to place the glenoid baseplate in the desired position with the desired version and inclination. Most of these systems also provide a 3-D model of the patient’s glenoid so that surgeons can visualize glenoid deformities and the correct guide placement on the glenoid. Single-use PSI systems are available from DJO Global, Wright Medical Group, and Zimmer Biomet. The second category of PSI is reusable and is available from Arthrex. The guide pin for this system is adjusted to fit individual patient anatomy and guide the guide pin into the glenoid in a location and orientation preplanned on the CT-scan-based computer software or using a 3-D model of the patient’s glenoid (Table).

Table. Details of Available Patient-Specific Instrumentation Systems

The DJO Global patient-specific guide is termed as the MatchPoint System. This system creates 3-D renderings of the scapula and allows the surgeon to manipulate the glenoid baseplate on the scapula. The surgeon chooses the glenoid baseplate, location, version, and inclination on the computerized 3-D model. The system then fabricates a guide pin matching the computerized template that references the patient’s glenoid surface with a hook to orient it against the coracoid. A 3-D model of the glenoid is also provided along with the customized guide pin.

Continue to: Blueprint 3D Planning + PSI...

Blueprint 3D Planning + PSI (Wright Medical Group) allows custom placement of the glenoid version, inclination, and position on computerized 3-D models of the patient’s scapula. This PSI references the glenoid with 4 feet that captures the edge of the patient’s glenoid at specific locations and is unique because it allows the surgeon to control where on the glenoid edge to 4 feet contact as long as 1 foot is placed on the posterior edge of the glenoid and the remaining 3 feet are placed on the anterior edge of the glenoid. A 3-D model of the glenoid is also provided with this guide.

The Zimmer Biomet patient-specific guide is termed as the Zimmer Patient Specific Instruments Shoulder. Its computer software allows custom placement of the glenoid as well, but it also includes computerized customization of the reaming depth, screw angles, and screw lengths to optimize fixation. Their system includes a central guide pin to set the glenoid baseplate’s location and orientation, a reaming guide to control reaming depth and direction, a roll guide to control the glenoid baseplate’s rotation, and a drill guide to control the screw direction. They also provide a 3-D model of the glenoid.

The Arthrex Virtual Implant Positioning (VIP) System is similar to other systems in that its 3-D planning software is based on CT images uploaded by the surgeon. The unique aspect of this system is that the guide pin is adjusted by the surgeon for each individual patient based on instructions generated by the planning software; however, after use, the instruments are resterilized and reused on subsequent patients (Figures 1A, 1B). In this manner, their instruments are reusable and allow custom adjustment for each patient with the ability to set the pin location and glenoid version in a patient-specific manner. This has the potential benefit of keeping costs down. For more complex deformity cases, the Arthrex VIP System can also 3-D-print a sterile model of the glenoid to help surgeons appreciate the deformity better (Figure 2).

DATA ON PATIENT-SPECIFIC INSTRUMENTS

Several studies have measured the accuracy of patient-specific guides and have compared the accuracy of patient-specific guides to that of traditional methods. Levy and colleagues²³ investigated the accuracy of single-use patient-specific guides compared to that of preoperative plans. They used patient-specific guides on 14 cadaveric shoulders based on plans developed by virtual preoperative 3-D planning system using CT images. Once the guide pin was drilled using the patient-specific guide, they obtained a second CT scan to compare the accuracy of the patient-specific guide to the surgical plan generated preoperatively. They found that the translational accuracy of the starting point for the guide pin averaged 1.2 mm ± 0.7 mm, the accuracy of the inferior inclination was 1.2° ± 1.2°, and the accuracy of the glenoid version was 2.6° ± 1.7°. They concluded that patient-specific guides were highly accurate in reproducing the starting point, inclination, and version set on preoperative guides.

Walch and colleagues²⁴ subsequently performed a similar study using 15 cadaveric scapulae without any other shoulder soft tissue or bone attached. They also used CT-scan-based 3-D planning software to plan their glenoid placement with a subsequently fabricated single-use patient-specific guide used to place a guide pin. They obtained a second CT scan after guide pin implantation and compared the preoperative plan with the subsequent guide pin. They found a mean entry point position error of 1.05 mm ± 0.31 mm, a mean inclination error of 1.42° ± 1.37°, and a mean version error of 1.64° ± 1.01°.

Continue to: Throckmorton and colleagues...

Throckmorton and colleagues²¹ used 70 cadaveric shoulders with radiographically confirmed arthritis and randomized them to undergo either anatomic or reverse TSA using either a patient-specific guide or standard instrumentation. Postoperative CT scans were used to evaluate the glenoid inclination, version, and starting point. They found that glenoid components implanted using patient-specific guides were more accurate than those placed using traditional instrumentation. The average deviation from intended inclination was 3° for patient-specific guides and 7° for traditional instrumentation, the average deviation from intended version was 5° for patient-specific guides and 8° for traditional instrumentation, and the average deviation in intended starting point was 2 mm for patient-specific guides and 3 mm for traditional instrumentation. They also analyzed significantly malpositioned components as defined by a variation in version or inclination of >10° or >4 mm in starting point. They found that 6 of their 35 glenoids using patient-specific guides were significantly malpositioned compared to 23 of 35 glenoids using traditional instrumentation. They concluded that patient-specific guides were more accurate and reduced the number of significantly malpositioned implants when compared with traditional instrumentation.

Early and colleagues²⁵ analyzed the effect of severe glenoid bone defects on the accuracy of patient-specific guides compared with traditional guides. Using 10 cadaveric shoulders, they created anterior, central, or posterior glenoid defects using a reamer and chisel to erode the bone past the coracoid base. Subsequent CT scans were performed on the specimens, and patient-specific guides were fabricated and used for reverse TSA in 5 of the 10 specimens. A reverse TSA was performed using traditional instrumentation in the remaining 5 specimens. They found that the average deviation in inclination and version from preoperative plan was more accurate in the patient-specific guide cohort than that in the traditional instrument cohort, with an average deviation in inclination and version of 1.2° ± 1.2° and 1.8° ± 1.2° respectively for the cohort using patient-specific instruments vs 2.8° ± 1.8° and 3.5° ± 3° for the cohort using traditional instruments. They also found that their total bone screw lengths were longer in the patient-specific guide group than those in the traditional group, with screws averaging 52% of preoperatively planned length in the traditional instrument cohort vs 89% of preoperatively planned length in the patient-specific instrument cohort.

Gauci and colleagues²⁶ measured the accuracy of patient-specific guides in vivo in 17 patients receiving TSA. Preoperative CT scans were used to fabricate patient-specific guides, and postoperative CT scans were used to measure version, inclination, and error of entry in comparison with the templated goals used to create patient-specific guides. They found a mean error in version and inclination of 3.4° and 1.8°, respectively, and a mean error in entry of 0.9 mm of translation on the glenoid. Dallalana and colleagues²⁷ performed a very similar study on 20 patients and found a mean deviation in glenoid version of 1.8° ± 1.9°, a mean deviation in glenoid inclination of 1.3° ± 1.0°, a mean translation in anterior-posterior plane of 0.5 mm ± 0.3 mm, and a mean translation in the superior-inferior plane of 0.8 mm ± 0.5 mm.

Hendel and colleagues²⁸ performed a randomized prospective clinical trial comparing patient-specific guides with traditional methods for glenoid insertion. They randomized 31 patients to receive a glenoid implant using either a patient-specific guide or traditional methods and compared glenoid retroversion and inclination with their preoperative plan. They found an average version deviation of 6.9° in the traditional method cohort and 4.3° in the patient-specific guide cohort. Their average deviation in inclination was 11.6° in the traditional method cohort and 2.9° in the patient-specific guide cohort. For patients with preoperative retroversion >16°, the average deviation was 10° in the standard surgical cohort and 1.2° in the patient-specific instrument cohort. Their data suggest that increasing preoperative retroversion leads to an increased version variation from preoperative plan.

Iannotti and colleagues²⁹ randomly assigned 46 patients to preoperatively undergo either CT scan with 3-D templating of glenoid component without patient-specific guide fabrication or CT scan with 3-D templating and patient-specific guide fabrication prior to receiving a TSA. They recorded the postoperative inclination and version for each patient and compared them to those of a nonrandomized control group of 17 patients who underwent TSA using standard instrumentation. They found no difference between the cohorts with or without patient-specific guide use with regard to implant location, inclination, or version; however, they did find a difference between the combined 3-D templating cohort compared with their standard instrumentation cohort. They concluded that 3-D templating significantly improved the surgeons’ ability to correctly position the glenoid component with or without the fabrication and the use of a patient-specific guide.

Continue to: Denard and colleagues...

Denard and colleagues³⁰ compared the preoperative glenoid version and inclination measurements obtained using the Blueprint 3D Planning + PSI software and the VIP System 3D planning software. They analyzed the preoperative CT scans of 63 consecutive patients undergoing either TSA or reverse TSA using both the Blueprint and the VIP System 3D planning software and compared the resulting native glenoid version and inclination measured by the software. They found a statistically significant difference (P = 0.04) in the version measurements provided by the different planning software; however, the differences found in inclination did not reach statistical significance (P = 0.463). In 19 of the 63 patients (30%), the version measurements between the systems were >5°, and in 29 of the 63 patients (46%), the inclination measurements between the systems were 5° or greater. In addition, 12 of the 63 patients (19%) had both version and inclination measurement differences of >5° between the systems. In total, they found that 35 of the 63 patients had at least 1 measurement that varied by >5° between the systems, and that in 15 patients (24%), 1 measurement varied by >10°. Their data demonstrate considerable variability in the preoperative measurements provided by different 3-D planning software systems, and that further study of each commercially available 3-D planning software system is needed to evaluate their accuracy.

CONCLUSION

Optimal outcomes following TSA and reverse TSA are dependent on proper implant position. Multiple studies have demonstrated improved accuracy in implant positioning with the use of patient-specific guides compared to that with traditional methods. Currently, there are no studies comparing the clinical outcomes of patient-specific guides to those of traditional methods of glenoid placement, and limited research had been done comparing the accuracy of each system’s 3-D planning software with each other and with standardized measurements of glenoid version and inclination. Further research is required to determine the accuracy of each commercially available 3-D planning software system as well as the clinical benefit of patient-specific guides in shoulder arthroplasty.

ABSTRACT

Optimal outcomes following total shoulder arthroplasty TSA and reverse shoulder arthroplasty RSA are dependent on proper implant position. Multiple cadaver studies have demonstrated improved accuracy of implant positioning with use of patient-specific guides/instrumentation compared to traditional methods. At this time, there are 3 commercially available single use patient-specific instrumentation systems and 1 commercially available reusable patient-specific instrumentation system. Currently though, there are no studies comparing the clinical outcomes of patient-specific guides to those of traditional methods of glenoid placement, and limited research has been done comparing the accuracy of each system’s 3-dimensional planning software. Future work is necessary to elucidate the ideal indications for the use of patient-specific guides and instrumentation, but it is likely, particularly in the setting of advanced glenoid deformity, that these systems will improve a surgeon's ability to put the implant in the best position possible.

Continue to: Optimal functional recovery...

Optimal functional recovery and implant longevity following both total shoulder arthroplasty (TSA) and reverse shoulder arthroplasty (RSA) depend, in large part, on proper placement of the glenoid component. Glenoid component malpositioning has an adverse effect on shoulder stability, range of motion (ROM), impingement, and glenoid implant longevity.

Traditionally, glenoid component positioning has been done manually by the surgeons based on their review of preoperative films and knowledge of glenoid anatomy. Anatomic studies have demonstrated high individual variability in the version of the native glenoid, thus making ideal placement of the initial glenoid guide pin difficult using standard guide pin guides.¹

The following 2 methods have been described for improving the accuracy of glenoid guide pin insertion and subsequent glenoid implant placement: (1) computerized navigation and (2) patient-specific guides/instrumentation. Although navigated shoulder systems have demonstrated improved accuracy in glenoid placement compared with traditional methods, navigated systems require often large and expensive systems for implementation. The majority of them also require placement of guide pins or arrays on scapular bony landmarks, likely leading to an increase in operative time and possible iatrogenic complications, including fracture and pin site infections.

This review focuses on the use of patient-specific guides/instrumentation in shoulder arthroplasty. This includes the topic of proper glenoid and glenosphere placement as well as patient-specific guides/instrumentation and their accuracy.

GLENOID PLACEMENT

Glenohumeral osteoarthritis is the most common indication for TSA² and commonly results in glenoid deformity. Using computed tomography (CT) scans of 45 arthritic shoulders and 19 normal shoulders, Mullaji and colleagues³ reported that the anteroposterior dimensions of the glenoid were increased by an average of 5 mm to 8 mm in osteoarthritic shoulders and by an average of 6 mm in rheumatoid arthritic shoulders compared to those in normal shoulders. A retrospective review of serial CT scans performed preoperatively on 113 osteoarthritic shoulders by Walch and colleagues⁴ demonstrated an average retroversion of 16°, and it has been the basis for the commonly used Walch classification of glenoid wear in osteoarthritis. Increased glenoid wear and increased glenoid retroversion make the proper restoration of glenoid version, inclination, and offset during shoulder arthroplasty more difficult and lead to increased glenoid component malpositioning.

Continue to: The ideal placement of the glenoid...

The ideal placement of the glenoid to maximize function, ROM, and implant longevity is in a mechanically neutral alignment with no superoinferior inclination¹ and neutral version with respect to the transverse axis of the scapula.⁵

Improper glenoid positioning has an adverse effect on the functional results of shoulder arthroplasty. Yian and colleagues⁶ evaluated 47 cemented, pegged glenoids using standard radiography and CT scans at a mean follow-up of 40 months. They observed a significant correlation between increased glenoid component retroversion and lower Constant scores. Hasan and colleagues⁷ evaluated 139 consecutive patients who were dissatisfied with the result of their primary arthroplasty and found that 28% of them had at least 1 substantially malpositioned component identified either on radiography or during a revision surgery. They also found a significant correlation between stiffness, instability, and component malposition in their cohort.

Glenoid longevity is also dependent on proper component positioning, with the worst outcomes coming if the glenoid is malaligned with either superior or inferior inclination. Hasan and colleagues⁷ found that of their 74 patients with failed TSAs, 44 patients (59%) demonstrated mechanical loosening of their glenoid components either radiographically or during revision surgery, and 10 of their 44 patients with loose glenoids (23%) also had a malpositioned component. Using finite element analysis, Hopkins and colleagues⁸ analyzed the stresses through the cement mantle in glenoid prostheses that were centrally aligned, superiorly inclined, inferiorly inclined, anteverted, and retroverted. They found that malalignment of the glenoid increases the stresses through the cement mantle, leading to increased likelihood of mantle failure compared to that of centrally aligned glenoids, especially if there is malalignment with superior or inferior inclination or retroversion.

The accuracy of traditional methods of glenoid placement using an initial guide pin is limited and decreases with increasing amounts of glenoid deformity and retroversion. Iannotti and colleagues ⁹ investigated 13 patients undergoing TSA with an average preoperative retroversion of 13° and evaluated them using a 3-dimensional (3-D) surgical simulator. They found that the postoperative glenoid version was within 5° of ideal version in only 7 of their 13 patients (54%) and within 10° of ideal version in only 10 of their 13 patients (77%). In their study, the ideal version was considered to be the version as close to perpendicular to the plane of the scapula as possible with complete contact of the back side of the component on glenoid bone and maintenance of the center peg of the component within bone. In addition, they found that of their 7 patients with preoperative retroversion >10°, only 1 patient (14%) had a postoperative glenoid with <10° of retroversion with regard to the plane of the scapula and that all 6 of their patients with preoperative glenoid retroversion of <10° had a postoperative glenoid version of <10°.

Preoperative CT scans are much more accurate at determining glenoid version and thus how much glenoid correction is required to reestablish neutral version than plain radiography. Nyffeler and colleagues¹⁰ compared CT scans with axillary views for comparing glenoid version in 25 patients with no shoulder prosthesis present and 25 patients with a TSA in place. They found that glenoid retroversion was overestimated on plain radiographs in 86% of their patients with an average difference between CT and plain radiography of 6.4° and a maximum difference of 21°. They also found poor interobserver reliability in the plain radiography group and good interobserver reliability in the CT group, with coefficients of correlation of 0.77 for the plain radiography group and 0.93 for the CT group. Thus, they concluded that glenoid version cannot be accurately measured by plain radiography and that CT should be used. Hoenecke and colleagues¹¹ subsequently evaluated 33 patients scheduled for TSA and found that CT version measurements made on 2-dimensional (2-D) CT slices compared with 3-D-reconstructed models of the same CT slices differed by an average of 5.1° because the axial CT slices were most often made perpendicular to the axis of the patient’s torso and not perpendicular to the body of the scapula. Accurate version assessment is critically important in planning for the degree of correction required to restore neutral glenoid version, and differences of 6.4° between CT assessment and plain radiography, and 5.1° between 2-D and 3-D CT scan assessments may lead to inadequate version correction intraoperatively and inferior postoperative results.

Continue to: GLENOSPHERE PLACEMENT

The most common indication for reverse TSA is rotator cuff arthropathy characterized by rotator cuff dysfunction and end-stage glenohumeral arthritis.¹² These patients require accurate and reproducible glenoid placement to optimize their postoperative range of motion and stability and minimize scapular notching.

Ideal glenosphere placement is the location and orientation that maximizes impingement-free ROM and stability while avoiding notching. Individual patient anatomy determines ideal placement; however, several guidelines for placement include inferior translation on the glenoid with neutral to inferior inclination. Gutiérrez and colleagues¹³ developed a computer model to assess the hierarchy of surgical factors affecting the ROM after a reverse TSA. They found that lateralizing the center of rotation gave the largest increase in impingement-free abduction, followed closely by inferior translation of the glenosphere on the glenoid.

Avoiding scapular notching is also a very important factor in ideal glenosphere placement. Scapular notching can be described as impingement of the humeral cup against the scapular neck during arm adduction and/or humeral rotation. Gutiérrez and colleagues¹³ also found that decreasing the neck shaft angle to create a more varus proximal humerus was the most important factor in increasing the impingement-free adduction. Roche and colleagues¹⁴ reviewed the radiographs of 151 patients who underwent primary reverse TSA at a mean follow-up of 28.3 months postoperatively; they found that 13.2% of their patients had a notch and that, on average, their patients who had no scapular notch had significantly more inferior glenosphere overhang than those who had a scapular notch. Poon and colleagues¹⁵ found that a glenosphere overhang of >3.5 mm prevented notching in their randomized control trial comparing concentrically and eccentrically placed glenospheres. Multiple other studies have demonstrated similar results and recommended inferior glenoid translation and inferior glenoid inclination to avoid scapular notching.^16,17 Lévigne and colleagues¹⁸ retrospectively reviewed 337 reverse TSAs and observed a correlation between scapular notching and radiolucencies around the glenosphere component, with 14% of patients with scapular notching displaying radiolucencies vs 4% of patients without scapula notching displaying radiolucencies.

Several studies have also focused on the ideal amount of inferior glenoid inclination to maximize impingement-free ROM. Li and colleagues¹⁷ performed a computer simulation study on the Comprehensive Reverse Shoulder System (Zimmer Biomet) to determine impingement-free internal and external ROM with varying amounts of glenosphere offset, translation, and inclination. They found that progressive glenosphere inferior inclination up to 30° improved impingement-free rotational ROM at all degrees of scaption. Gutiérrez and colleagues¹⁹ used computer modeling to compare concentrically placed glenospheres in neutral inclination with eccentrically placed glenospheres in varying degrees of inclination. They found that the lowest forces across the baseplate occurred in the lateralized and inferiorly inclined glenospheres, and the highest forces occurred in the lateralized and superiorly inclined glenospheres. Together, these studies show that inferior glenoid inclination increases impingement-free ROM and, combined with lateralization, may result in improved glenosphere longevity due to significantly decreased forces at the RSA glenoid baseplate when compared to that at superiorly inclined glenoids.

The ideal amount of mediolateral glenosphere offset has not been well defined. Grammont design systems place the center of rotation of the glenosphere medial to the glenoid baseplate together with valgus humeral component neck shaft angles of around 155°. These design elements are believed to decrease shear stresses through the glenoid baseplate to the glenoid interface and improve shoulder stability, but they are also associated with reduced impingement-free ROM and increased rates of scapular notching.¹³ This effect is accentuated in patients with preexisting glenoid bone loss and/or congenitally short scapular necks that further medialize the glenosphere. Medialization of the glenosphere may also shorten the remaining rotator cuff muscles and result in decreased implant stability and external rotation strength. Several implant systems have options to vary the amount of lateral offset. The correct amount of lateral offset for each patient requires the understanding that improving patients’ impingement-free ROM by increasing the amount of lateral offset comes at the price of increasing the shear forces experienced by the interface between the glenoid baseplate and the glenoid. As glenoid fixation technology improves increased lateralization of glenospheres without increased rates of glenoid baseplate, loosening should improve the ROM after reverse TSA.

Continue to: Regardless of the intraoperative goals...

Regardless of the intraoperative goals for placement and orientation of the glenosphere components, it is vitally important to accurately and consistently meet those goals for achieving optimal patient outcomes. Verborgt and colleagues²⁰ implanted 7 glenospheres in cadaveric specimens without any glenohumeral arthritis using standard techniques to evaluate the accuracy of glenosphere version and inclination. Their goal was to place components in neutral version and with 10° of inferior inclination. Their average glenoid version postoperatively was 8.7° of anteversion, and their average inclination was 0.9° of superior inclination. Throckmorton and colleagues²¹ randomized 35 cadaveric shoulders to receive either an anatomic or a reverse total shoulder prosthesis from high-, mid-, and low-volume surgeons. They found that components placed using traditional guides averaged 6° of deviation in version and 5° of deviation in inclination from their target values, with no significant differences between surgeons of different volumes.

PATIENT-SPECIFIC GUIDES/INSTRUMENTATION

Patient-specific guides/instrumentation and intraoperative navigation are the 2 techniques that have been used to improve the accuracy of glenoid and glenosphere placement. Both techniques require the use of high-resolution CT scans and computer software to determine the proper position for glenoid or glenosphere placement based on the patient’s individual anatomy. Patient-specific guides and instrumentation use the data acquired from a CT scan to generate a preoperative plan for the location and orientation of the glenoid baseplate. Once the surgeon approves the preoperative plan, a patient-specific guide is created using the patient’s glenoid as a reference for the location and orientation of the central guide pin. The location of the central guide pin on the glenoid determines the center of the glenoid baseplate, and the guide pin’s orientation determines the version and inclination of the glenoid or the glenosphere. Once the guide pin is placed in the glenoid, the remainder of the glenoid implantation uses the guide pin as a reference, and, in that way, patient-specific guides control the orientation of the glenoid at the time of surgery.

Intraoperative navigation uses an optical tracking system to determine the location and orientation of the central guide pin. Navigation systems require intraoperative calibration of the optical tracking system before they can track the location of implantation relative to bony landmarks on the patient’s scapula. Their advantage over patient-specific instrumentation (PSI) is that they do not require the manufacture of a custom guide; however, they may add significantly increased cost and surgical time due to the need for calibration prior to use and the cost of the navigation system along with any disposable components associated with it. Kircher and colleagues²² performed a prospective randomized clinical study of navigation-aided TSA compared with conventional TSA and found that operating time was significantly increased for the navigated group with an average operating room time of 169.5 minutes compared to 138 minutes for the conventional group. They also found that navigation had to be abandoned in 37.5% of their navigated patients due to technical errors during glenoid referencing.

COMMERCIAL PATIENT-SPECIFIC INSTRUMENTATION SYSTEMS

The 2 types of PSI that are currently available are single-use PSI and reusable PSI. The single-use PSI involves the fabrication of unique guides based on surgeon-approved preoperative plans generated by computer-software-processed preoperative CT scans. The guides are fabricated to rest on the glenoid articular surface and direct the guide pin to the correct location and in the correct direction to place the glenoid baseplate in the desired position with the desired version and inclination. Most of these systems also provide a 3-D model of the patient’s glenoid so that surgeons can visualize glenoid deformities and the correct guide placement on the glenoid. Single-use PSI systems are available from DJO Global, Wright Medical Group, and Zimmer Biomet. The second category of PSI is reusable and is available from Arthrex. The guide pin for this system is adjusted to fit individual patient anatomy and guide the guide pin into the glenoid in a location and orientation preplanned on the CT-scan-based computer software or using a 3-D model of the patient’s glenoid (Table).

Table. Details of Available Patient-Specific Instrumentation Systems

The DJO Global patient-specific guide is termed as the MatchPoint System. This system creates 3-D renderings of the scapula and allows the surgeon to manipulate the glenoid baseplate on the scapula. The surgeon chooses the glenoid baseplate, location, version, and inclination on the computerized 3-D model. The system then fabricates a guide pin matching the computerized template that references the patient’s glenoid surface with a hook to orient it against the coracoid. A 3-D model of the glenoid is also provided along with the customized guide pin.

Continue to: Blueprint 3D Planning + PSI...

Blueprint 3D Planning + PSI (Wright Medical Group) allows custom placement of the glenoid version, inclination, and position on computerized 3-D models of the patient’s scapula. This PSI references the glenoid with 4 feet that captures the edge of the patient’s glenoid at specific locations and is unique because it allows the surgeon to control where on the glenoid edge to 4 feet contact as long as 1 foot is placed on the posterior edge of the glenoid and the remaining 3 feet are placed on the anterior edge of the glenoid. A 3-D model of the glenoid is also provided with this guide.

The Zimmer Biomet patient-specific guide is termed as the Zimmer Patient Specific Instruments Shoulder. Its computer software allows custom placement of the glenoid as well, but it also includes computerized customization of the reaming depth, screw angles, and screw lengths to optimize fixation. Their system includes a central guide pin to set the glenoid baseplate’s location and orientation, a reaming guide to control reaming depth and direction, a roll guide to control the glenoid baseplate’s rotation, and a drill guide to control the screw direction. They also provide a 3-D model of the glenoid.

The Arthrex Virtual Implant Positioning (VIP) System is similar to other systems in that its 3-D planning software is based on CT images uploaded by the surgeon. The unique aspect of this system is that the guide pin is adjusted by the surgeon for each individual patient based on instructions generated by the planning software; however, after use, the instruments are resterilized and reused on subsequent patients (Figures 1A, 1B). In this manner, their instruments are reusable and allow custom adjustment for each patient with the ability to set the pin location and glenoid version in a patient-specific manner. This has the potential benefit of keeping costs down. For more complex deformity cases, the Arthrex VIP System can also 3-D-print a sterile model of the glenoid to help surgeons appreciate the deformity better (Figure 2).

DATA ON PATIENT-SPECIFIC INSTRUMENTS

Several studies have measured the accuracy of patient-specific guides and have compared the accuracy of patient-specific guides to that of traditional methods. Levy and colleagues²³ investigated the accuracy of single-use patient-specific guides compared to that of preoperative plans. They used patient-specific guides on 14 cadaveric shoulders based on plans developed by virtual preoperative 3-D planning system using CT images. Once the guide pin was drilled using the patient-specific guide, they obtained a second CT scan to compare the accuracy of the patient-specific guide to the surgical plan generated preoperatively. They found that the translational accuracy of the starting point for the guide pin averaged 1.2 mm ± 0.7 mm, the accuracy of the inferior inclination was 1.2° ± 1.2°, and the accuracy of the glenoid version was 2.6° ± 1.7°. They concluded that patient-specific guides were highly accurate in reproducing the starting point, inclination, and version set on preoperative guides.

Walch and colleagues²⁴ subsequently performed a similar study using 15 cadaveric scapulae without any other shoulder soft tissue or bone attached. They also used CT-scan-based 3-D planning software to plan their glenoid placement with a subsequently fabricated single-use patient-specific guide used to place a guide pin. They obtained a second CT scan after guide pin implantation and compared the preoperative plan with the subsequent guide pin. They found a mean entry point position error of 1.05 mm ± 0.31 mm, a mean inclination error of 1.42° ± 1.37°, and a mean version error of 1.64° ± 1.01°.

Continue to: Throckmorton and colleagues...

Throckmorton and colleagues²¹ used 70 cadaveric shoulders with radiographically confirmed arthritis and randomized them to undergo either anatomic or reverse TSA using either a patient-specific guide or standard instrumentation. Postoperative CT scans were used to evaluate the glenoid inclination, version, and starting point. They found that glenoid components implanted using patient-specific guides were more accurate than those placed using traditional instrumentation. The average deviation from intended inclination was 3° for patient-specific guides and 7° for traditional instrumentation, the average deviation from intended version was 5° for patient-specific guides and 8° for traditional instrumentation, and the average deviation in intended starting point was 2 mm for patient-specific guides and 3 mm for traditional instrumentation. They also analyzed significantly malpositioned components as defined by a variation in version or inclination of >10° or >4 mm in starting point. They found that 6 of their 35 glenoids using patient-specific guides were significantly malpositioned compared to 23 of 35 glenoids using traditional instrumentation. They concluded that patient-specific guides were more accurate and reduced the number of significantly malpositioned implants when compared with traditional instrumentation.

Early and colleagues²⁵ analyzed the effect of severe glenoid bone defects on the accuracy of patient-specific guides compared with traditional guides. Using 10 cadaveric shoulders, they created anterior, central, or posterior glenoid defects using a reamer and chisel to erode the bone past the coracoid base. Subsequent CT scans were performed on the specimens, and patient-specific guides were fabricated and used for reverse TSA in 5 of the 10 specimens. A reverse TSA was performed using traditional instrumentation in the remaining 5 specimens. They found that the average deviation in inclination and version from preoperative plan was more accurate in the patient-specific guide cohort than that in the traditional instrument cohort, with an average deviation in inclination and version of 1.2° ± 1.2° and 1.8° ± 1.2° respectively for the cohort using patient-specific instruments vs 2.8° ± 1.8° and 3.5° ± 3° for the cohort using traditional instruments. They also found that their total bone screw lengths were longer in the patient-specific guide group than those in the traditional group, with screws averaging 52% of preoperatively planned length in the traditional instrument cohort vs 89% of preoperatively planned length in the patient-specific instrument cohort.

Gauci and colleagues²⁶ measured the accuracy of patient-specific guides in vivo in 17 patients receiving TSA. Preoperative CT scans were used to fabricate patient-specific guides, and postoperative CT scans were used to measure version, inclination, and error of entry in comparison with the templated goals used to create patient-specific guides. They found a mean error in version and inclination of 3.4° and 1.8°, respectively, and a mean error in entry of 0.9 mm of translation on the glenoid. Dallalana and colleagues²⁷ performed a very similar study on 20 patients and found a mean deviation in glenoid version of 1.8° ± 1.9°, a mean deviation in glenoid inclination of 1.3° ± 1.0°, a mean translation in anterior-posterior plane of 0.5 mm ± 0.3 mm, and a mean translation in the superior-inferior plane of 0.8 mm ± 0.5 mm.

Hendel and colleagues²⁸ performed a randomized prospective clinical trial comparing patient-specific guides with traditional methods for glenoid insertion. They randomized 31 patients to receive a glenoid implant using either a patient-specific guide or traditional methods and compared glenoid retroversion and inclination with their preoperative plan. They found an average version deviation of 6.9° in the traditional method cohort and 4.3° in the patient-specific guide cohort. Their average deviation in inclination was 11.6° in the traditional method cohort and 2.9° in the patient-specific guide cohort. For patients with preoperative retroversion >16°, the average deviation was 10° in the standard surgical cohort and 1.2° in the patient-specific instrument cohort. Their data suggest that increasing preoperative retroversion leads to an increased version variation from preoperative plan.

Iannotti and colleagues²⁹ randomly assigned 46 patients to preoperatively undergo either CT scan with 3-D templating of glenoid component without patient-specific guide fabrication or CT scan with 3-D templating and patient-specific guide fabrication prior to receiving a TSA. They recorded the postoperative inclination and version for each patient and compared them to those of a nonrandomized control group of 17 patients who underwent TSA using standard instrumentation. They found no difference between the cohorts with or without patient-specific guide use with regard to implant location, inclination, or version; however, they did find a difference between the combined 3-D templating cohort compared with their standard instrumentation cohort. They concluded that 3-D templating significantly improved the surgeons’ ability to correctly position the glenoid component with or without the fabrication and the use of a patient-specific guide.

Continue to: Denard and colleagues...

Denard and colleagues³⁰ compared the preoperative glenoid version and inclination measurements obtained using the Blueprint 3D Planning + PSI software and the VIP System 3D planning software. They analyzed the preoperative CT scans of 63 consecutive patients undergoing either TSA or reverse TSA using both the Blueprint and the VIP System 3D planning software and compared the resulting native glenoid version and inclination measured by the software. They found a statistically significant difference (P = 0.04) in the version measurements provided by the different planning software; however, the differences found in inclination did not reach statistical significance (P = 0.463). In 19 of the 63 patients (30%), the version measurements between the systems were >5°, and in 29 of the 63 patients (46%), the inclination measurements between the systems were 5° or greater. In addition, 12 of the 63 patients (19%) had both version and inclination measurement differences of >5° between the systems. In total, they found that 35 of the 63 patients had at least 1 measurement that varied by >5° between the systems, and that in 15 patients (24%), 1 measurement varied by >10°. Their data demonstrate considerable variability in the preoperative measurements provided by different 3-D planning software systems, and that further study of each commercially available 3-D planning software system is needed to evaluate their accuracy.

CONCLUSION

Optimal outcomes following TSA and reverse TSA are dependent on proper implant position. Multiple studies have demonstrated improved accuracy in implant positioning with the use of patient-specific guides compared to that with traditional methods. Currently, there are no studies comparing the clinical outcomes of patient-specific guides to those of traditional methods of glenoid placement, and limited research had been done comparing the accuracy of each system’s 3-D planning software with each other and with standardized measurements of glenoid version and inclination. Further research is required to determine the accuracy of each commercially available 3-D planning software system as well as the clinical benefit of patient-specific guides in shoulder arthroplasty.

ABSTRACT

The use of arthroscopy for purely diagnostic purposes has been largely supplanted by noninvasive technologies, such as magnetic resonance imaging (MRI). The mi-eye^+TM (Trice Medical) technology is a small-bore needle unit for in-office arthroscopy. We conducted a pilot study comparing the mi-eye^+TM unit with MRI, using surgical arthroscopy as a gold-standard reference. We hypothesized that the mi-eye^+TM needle arthroscope, which can be used in an office setting, would be equivalent to MRI for the diagnosis of intra-articular pathology of the knee.

This prospective, multicenter, observational study was approved by the Institutional Review Board. There were 106 patients (53 males, 53 females) in the study. MRIs were interpreted by musculoskeletally trained radiologists. The study was conducted in the operating room using the mi-eye^+TM device. The mi-eye^{+ TM} device findings were compared with the MRI findings within individual pathologies, and a “per-patient” analysis was performed to compare the arthroscopic findings with those of the mi-eye^+TM and the MRI. Additionally, we identified all mi-eye^+TM findings and MRI findings that exactly matched the surgical arthroscopy findings.

The mi-eye^+TM demonstrated complete accuracy of all pathologies for 97 (91.5%) of the 106 patients included in the study, whereas MRI demonstrated complete accuracy for 65 patients (61.3%) (P < .0001). All discrepancies between mi-eye^+TM and arthroscopy were false-negative mi-eye^+TM results, as the mi-eye^+TM did not reveal some aspect of the knee’s pathology for 9 patients. The mi-eye^+TM was more sensitive than MRI in identifying meniscal tears (92.6% vs 77.8%; P = .0035) and more specific in diagnosing these tears (100% vs 41.7%; P < .0001).

The mi-eye^+TM device proved to be more sensitive and specific than MRI for intra-articular findings at time of knee arthroscopy. Certainly there are contraindications to using the mi-eye^+TM, and our results do not obviate the need for MRI, but our study did demonstrate that the mi-eye^+TM needle arthroscope can safely provide excellent visualization of intra-articular knee pathology.

Continue to: Surgical arthroscopy is the gold standard...

Surgical arthroscopy is the gold standard for the diagnosis of intra-articular knee pathologies. Nevertheless, the use of arthroscopy for purely diagnostic purposes has been largely supplanted by noninvasive technologies, such as magnetic resonance imaging (MRI). Although MRI is considered the standard diagnostic tool for acute and chronic soft-tissue injuries of the knee, its use is not without contraindication and some potential inconveniences. Contraindications to MRI are well documented. In terms of inconvenience, MRI usually requires a separate visit followed by another visit to the prescribing physician. In addition, required interpretation by a radiologist may lead to a delay in care and increase in cost.

In the early 1990s, in-office needle arthroscopy was described as a viable means of diagnosing pathologies and obtaining synovial biopsies from the knee.^1-3 Initial results were good, and the procedures had very low complication rates. Nevertheless, in-office arthroscopy of the knee is not yet widely performed, likely given concerns about the technical difficulties of in-office arthroscopy, the potential for patient discomfort, and the cumbersomeness of in-office arthroscopy units. However, significant advances have been made in the resolution capability of small-bore needle arthroscopy, resulting in much less painful procedures. Additionally, the early hardware designs, which mimicked operating room setups using towers, fluid irrigation systems, and larger arthroscopes, have been replaced with small-needle arthroscopes that use syringes for irrigation and tablet computers for visualization (Figures 1A, 1B).  

The mi-eye^+TM technology (Trice Medical) is a small-bore needle unit for in-office arthroscopy with digital optics that does not need an irrigation tower. We conducted a pilot study of the sensitivity and specificity of the mi-eye^+TM unit in comparison with MRI, using surgical arthroscopy as a gold-standard reference. We hypothesized that the mi-eye^+TM needle arthroscope, which can be used in an office setting, would be equivalent to the standard of care (MRI) for the diagnosis of intra-articular pathology of the knee.

METHODS

Central regulatory approval for this prospective, multicenter, observational study was obtained from the Western Institutional Review Board for 3 of the sites, and 1 institution required and was granted internal Institutional Review Board approval.

The study was performed by 4 sports medicine orthopedic surgeons experienced in using the mi-eye^+TM in-office arthroscope. Patients were enrolled from December 2015 through June 2016. Inclusion criteria were an indication for an arthroscopic procedure of the knee based on history, physical examination, and MRI findings. Patients were excluded from the study if there were any contraindications to completing an MRI. Acute hemarthroses of the knee or active systemic infections were also excluded. Once a patient was identified as meeting the criteria for participation, informed consent was obtained. Of the 113 patients who enrolled, 7 did not have a complete study dataset available, leaving 106 patients (53 males, 53 females) in the study. Mean age was 47 years (range, 18-82 years).

Continue to: A test result form was used...

A test result form was used to record mi-eye^+TM, surgical arthroscopy, and MRI results. This form required a “positive” or “negative” result for all of several diagnoses: medial and lateral meniscal tears, intra-articular loose body, osteoarthritis (OA), osteochondritis dissecans (OCD), and tears of the anterior and posterior cruciate ligaments (ACL, PCL). MRI was performed at a variety of imaging facilities, but the images were interpreted by musculoskeletally trained radiologists.

The study was conducted in the operating room. After the patient was appropriately anesthetized, and the extremity prepared and draped, the mi-eye^+TM procedure was performed immediately prior to surgical arthroscopy. A tourniquet was not used. At surgeon discretion, medial, lateral, or both approaches were used with the mi-eye^+TM, and diagnostic arthroscopy was performed. During the procedure, the mi-eye^+TM was advanced into the knee. Once in the synovial compartment, the external 14-gauge needle was retracted, exposing the unit’s optics. Visualization was improved by injecting normal saline through the lure lock in the mi-eye^+TM needle arthroscope. An average of 20 mL of saline was used, though the amount varied with surgeon discretion. Subsequently, the surgeon visualized structures in the knee and documented all findings.

At the end of the mi-eye^+TM procedure, the scheduled surgical arthroscopy was performed. After the surgical procedure, if there were no issues or complications, the patient was discharged from the study. No follow-up was required for the study, as arthroscopic findings served as the conclusive diagnosis for each patient, and no interventions were being studied. There were no complications related to use of the mi-eye^+TM.

The mi-eye^+TM device findings were compared with the MRI findings within individual pathologies, and a “per-patient” analysis was performed to compare the arthroscopic findings with those of the mi-eye^+TM and the MRI. Additionally, we identified all mi-eye^+TM findings and MRI findings that exactly matched the surgical arthroscopy findings. When a test had no false-positive or false-negative findings in comparison with surgical arthroscopy, it was identified as having complete accuracy for all intra-articular knee pathologies. For these methods, the 95% confidence interval was determined based on binomial distribution.

RESULTS

The mi-eye^{+ TM} demonstrated complete accuracy of all pathologies for 97 (91.5%) of the 106 patients included in the study, whereas MRI demonstrated complete accuracy for 65 patients (61.3%) (P < .0001). All discrepancies between mi-eye^+TM and surgical arthroscopy were false-negative mi-eye^+TM results, as the mi-eye^+TM did not reveal some aspect of the knee’s pathology for 9 patients. On the other hand, MRI demonstrated both false-negative and false-positive results, failing to reveal some aspect of the knee’s pathology for 31 patients, and potentially overcalling some aspect of the knee’s pathology among 18 patients.

Continue to: The pathology most frequently...

The pathology most frequently identified in the study was a meniscal tear. The mi-eye^+TM was more sensitive than MRI in identifying meniscal tears (92.6% vs 77.8%; P = .0035) and more specific in diagnosing these tears (100% vs 87.5%; P < .0002). The difference in specificity resulted from the false MRI diagnosis of a meniscal tear among 24 patients, who were found to have no tear by both mi-eye^+TM and surgical arthroscopy.

Table 1. Raw Data of mi-eye^+TM and Magnetic Resonance Imaging Findings

The second most frequent pathology was an intra-articular loose body. The mi-eye^+TM was more sensitive than MRI in identifying loose bodies (86.7% vs 20%; P = .0007). The specificity of the mi-eye^+TM and the specificity of MRI were equivalent in diagnosing loose bodies (100%). Table 1 and Table 2 show the complete set of diagnoses and associated diagnostic profiles.

Table 2. Diagnostic Profiles: Sensitivity and Specificity of mi-eye^+TM and Magnetic Resonance Imaging

^aBold P values are significant. Abbreviations: CI, confidence interval; MRI, magnetic resonance imaging; N/A, not applicable.

DISCUSSION

The overall accuracy of the mi-eye^+TM was superior to that of MRI relative to the arthroscopic gold standard in this pilot study. Other studies have demonstrated the accuracy, feasibility, and cost-efficacy of in-office arthroscopy. However, likely because of the cumbersomeness of in-office arthroscopy equipment and the potential for patient discomfort, the technique is not yet standard in the field. Recent advances in small-bore technology, digital optics, and ergonomics have addressed the difficulties associated with in-office arthroscopy, facilitating a faster and more efficient procedure. Our goal in this study was to evaluate the diagnostic capability of the mi-eye^+TM in-office arthroscopy unit, which features a small bore, digital optics, and functionality without an irrigation tower.

This study of 106 patients demonstrated equivalent or better accuracy of the mi-eye^+TM relative to MRI when compared with the gold standard of surgical arthroscopy. This was not surprising given that both the mi-eye^+TM and surgical arthroscopy are based on direct visualization of intra-articular pathology. The mi-eye^+TM unit identified more meniscal tears, intra-articular loose bodies, ACL tears, and OCD lesions than MRI did, and with enough power to demonstrate statistically significant improved sensitivity for meniscal tears and loose bodies. Furthermore, MRI demonstrated false-positive meniscal tears, ACL tears, OCD lesions, and OA, whereas the mi-eye^+TM did not demonstrate any false-positive results in comparison with surgical arthroscopy. This study demonstrated statistically significant improved specificity of the mi-eye⁺ compared with MRI in the diagnosis of meniscal tears and OA.

There are several limitations to our study. We refer to it as a pilot study because it was performed in a standard operating room. Before taking the technology to an outpatient setting, we wanted to confirm efficacy and safety in an operating room. However, the techniques used in this study are readily transferable to the outpatient clinic setting and to date have been used in more than 2000 cases.

Continue to: The specificity of MRI...

The specificity of MRI for meniscal tears was unexpectedly low compared with previous studies, which may reflect the multi-institution, multi-surgeon, multi-radiologist involvement in MRI interpretation.^4-10 MRI was performed at a variety of institutions without a standardized protocol. This lack of standardization of image capture and interpretation may have contributed to the suboptimal performance of MRI, falsely decreasing the potential ideal specificity for meniscal tears. Although this study may have underestimated the specificity of MRI for meniscal tears, we think the mi-eye^+TM and MRI results reported here reflect the findings of standard practice, without the standardization usually applied in studies. For example, a study of 139 knee MRI reports at 14 different institutions confirmed arthroscopic findings and concluded that 37% of the operations supported by a significant MRI finding were unjustified.¹¹ The authors attributed the rate of false-positive MRI findings to the wide variety of places where patients had their MRIs performed, and the subsequent variation in quality of imaging and MRI reader skill level.¹¹

Before inserting the mi-eye^+TM needle arthroscope, the surgeons had a working diagnosis of the pathology based on their clinical examination and MRI results. Clearly, this introduced a bias. Further studies will be conducted in a prospective, blinded manner to address this limitation.

Although studies of in-office arthroscopy technology date to the 1990s, there is an overall lack of data comparing in-office arthroscopy with MRI. Halbrecht and Jackson² conducted a study of 20 knee patients with both MRI and in-office needle arthroscopy. Overall, MRI was poor in detecting cartilage defects, with sensitivity of 34.6%, using the in-office arthroscopy as the confirmatory diagnosis. Although the authors did not compare in-office diagnoses with surgical arthroscopic findings, they concluded that office arthroscopy is an accurate and cost-efficient alternative to MRI in diagnostic evaluation of knee patients. Xerogeanes and colleagues¹² studied 110 patients in a prospective, blinded, multicenter trial comparing a minimally invasive office-based arthroscopy with MRI, using surgical arthroscopy as the confirmatory diagnosis. They concluded that the office-based arthroscope was statistically equivalent to diagnostic surgical arthroscopy and that it outperformed MRI in helping make accurate diagnoses. The authors applied a cost analysis to their findings and determined that office-based arthroscopy could result in an annual potential savings of $177 million for the healthcare system.¹²

Modern imaging sequences on high-Tesla MRI machines provide excellent visualization. Nevertheless, a significant number of patients do not undergo MRI, owing to time constraints, contraindications, body habitus, or anxiety/claustrophobia. Our study results confirmed that doctors treating such patients now have a viable alternative to help diagnose pathology.

CONCLUSION

The mi-eye^+TM device proved to be more sensitive and specific than MRI for intra-articular findings at the time of knee arthroscopy. Certainly there are contraindications to using the mi-eye^+TM, and our results do not obviate the need for MRI; our study did demonstrate that the mi-eye^+TM needle arthroscope can safely provide excellent visualization of intra-articular knee pathology. More studies of the mi-eye^+TM device in a clinical setting are warranted.

ABSTRACT

The use of arthroscopy for purely diagnostic purposes has been largely supplanted by noninvasive technologies, such as magnetic resonance imaging (MRI). The mi-eye^+TM (Trice Medical) technology is a small-bore needle unit for in-office arthroscopy. We conducted a pilot study comparing the mi-eye^+TM unit with MRI, using surgical arthroscopy as a gold-standard reference. We hypothesized that the mi-eye^+TM needle arthroscope, which can be used in an office setting, would be equivalent to MRI for the diagnosis of intra-articular pathology of the knee.

This prospective, multicenter, observational study was approved by the Institutional Review Board. There were 106 patients (53 males, 53 females) in the study. MRIs were interpreted by musculoskeletally trained radiologists. The study was conducted in the operating room using the mi-eye^+TM device. The mi-eye^{+ TM} device findings were compared with the MRI findings within individual pathologies, and a “per-patient” analysis was performed to compare the arthroscopic findings with those of the mi-eye^+TM and the MRI. Additionally, we identified all mi-eye^+TM findings and MRI findings that exactly matched the surgical arthroscopy findings.

The mi-eye^+TM demonstrated complete accuracy of all pathologies for 97 (91.5%) of the 106 patients included in the study, whereas MRI demonstrated complete accuracy for 65 patients (61.3%) (P < .0001). All discrepancies between mi-eye^+TM and arthroscopy were false-negative mi-eye^+TM results, as the mi-eye^+TM did not reveal some aspect of the knee’s pathology for 9 patients. The mi-eye^+TM was more sensitive than MRI in identifying meniscal tears (92.6% vs 77.8%; P = .0035) and more specific in diagnosing these tears (100% vs 41.7%; P < .0001).

The mi-eye^+TM device proved to be more sensitive and specific than MRI for intra-articular findings at time of knee arthroscopy. Certainly there are contraindications to using the mi-eye^+TM, and our results do not obviate the need for MRI, but our study did demonstrate that the mi-eye^+TM needle arthroscope can safely provide excellent visualization of intra-articular knee pathology.

Continue to: Surgical arthroscopy is the gold standard...

Surgical arthroscopy is the gold standard for the diagnosis of intra-articular knee pathologies. Nevertheless, the use of arthroscopy for purely diagnostic purposes has been largely supplanted by noninvasive technologies, such as magnetic resonance imaging (MRI). Although MRI is considered the standard diagnostic tool for acute and chronic soft-tissue injuries of the knee, its use is not without contraindication and some potential inconveniences. Contraindications to MRI are well documented. In terms of inconvenience, MRI usually requires a separate visit followed by another visit to the prescribing physician. In addition, required interpretation by a radiologist may lead to a delay in care and increase in cost.

In the early 1990s, in-office needle arthroscopy was described as a viable means of diagnosing pathologies and obtaining synovial biopsies from the knee.^1-3 Initial results were good, and the procedures had very low complication rates. Nevertheless, in-office arthroscopy of the knee is not yet widely performed, likely given concerns about the technical difficulties of in-office arthroscopy, the potential for patient discomfort, and the cumbersomeness of in-office arthroscopy units. However, significant advances have been made in the resolution capability of small-bore needle arthroscopy, resulting in much less painful procedures. Additionally, the early hardware designs, which mimicked operating room setups using towers, fluid irrigation systems, and larger arthroscopes, have been replaced with small-needle arthroscopes that use syringes for irrigation and tablet computers for visualization (Figures 1A, 1B).  

The mi-eye^+TM technology (Trice Medical) is a small-bore needle unit for in-office arthroscopy with digital optics that does not need an irrigation tower. We conducted a pilot study of the sensitivity and specificity of the mi-eye^+TM unit in comparison with MRI, using surgical arthroscopy as a gold-standard reference. We hypothesized that the mi-eye^+TM needle arthroscope, which can be used in an office setting, would be equivalent to the standard of care (MRI) for the diagnosis of intra-articular pathology of the knee.

METHODS

Central regulatory approval for this prospective, multicenter, observational study was obtained from the Western Institutional Review Board for 3 of the sites, and 1 institution required and was granted internal Institutional Review Board approval.

The study was performed by 4 sports medicine orthopedic surgeons experienced in using the mi-eye^+TM in-office arthroscope. Patients were enrolled from December 2015 through June 2016. Inclusion criteria were an indication for an arthroscopic procedure of the knee based on history, physical examination, and MRI findings. Patients were excluded from the study if there were any contraindications to completing an MRI. Acute hemarthroses of the knee or active systemic infections were also excluded. Once a patient was identified as meeting the criteria for participation, informed consent was obtained. Of the 113 patients who enrolled, 7 did not have a complete study dataset available, leaving 106 patients (53 males, 53 females) in the study. Mean age was 47 years (range, 18-82 years).

Continue to: A test result form was used...

A test result form was used to record mi-eye^+TM, surgical arthroscopy, and MRI results. This form required a “positive” or “negative” result for all of several diagnoses: medial and lateral meniscal tears, intra-articular loose body, osteoarthritis (OA), osteochondritis dissecans (OCD), and tears of the anterior and posterior cruciate ligaments (ACL, PCL). MRI was performed at a variety of imaging facilities, but the images were interpreted by musculoskeletally trained radiologists.

The study was conducted in the operating room. After the patient was appropriately anesthetized, and the extremity prepared and draped, the mi-eye^+TM procedure was performed immediately prior to surgical arthroscopy. A tourniquet was not used. At surgeon discretion, medial, lateral, or both approaches were used with the mi-eye^+TM, and diagnostic arthroscopy was performed. During the procedure, the mi-eye^+TM was advanced into the knee. Once in the synovial compartment, the external 14-gauge needle was retracted, exposing the unit’s optics. Visualization was improved by injecting normal saline through the lure lock in the mi-eye^+TM needle arthroscope. An average of 20 mL of saline was used, though the amount varied with surgeon discretion. Subsequently, the surgeon visualized structures in the knee and documented all findings.

At the end of the mi-eye^+TM procedure, the scheduled surgical arthroscopy was performed. After the surgical procedure, if there were no issues or complications, the patient was discharged from the study. No follow-up was required for the study, as arthroscopic findings served as the conclusive diagnosis for each patient, and no interventions were being studied. There were no complications related to use of the mi-eye^+TM.

The mi-eye^+TM device findings were compared with the MRI findings within individual pathologies, and a “per-patient” analysis was performed to compare the arthroscopic findings with those of the mi-eye^+TM and the MRI. Additionally, we identified all mi-eye^+TM findings and MRI findings that exactly matched the surgical arthroscopy findings. When a test had no false-positive or false-negative findings in comparison with surgical arthroscopy, it was identified as having complete accuracy for all intra-articular knee pathologies. For these methods, the 95% confidence interval was determined based on binomial distribution.

RESULTS

The mi-eye^{+ TM} demonstrated complete accuracy of all pathologies for 97 (91.5%) of the 106 patients included in the study, whereas MRI demonstrated complete accuracy for 65 patients (61.3%) (P < .0001). All discrepancies between mi-eye^+TM and surgical arthroscopy were false-negative mi-eye^+TM results, as the mi-eye^+TM did not reveal some aspect of the knee’s pathology for 9 patients. On the other hand, MRI demonstrated both false-negative and false-positive results, failing to reveal some aspect of the knee’s pathology for 31 patients, and potentially overcalling some aspect of the knee’s pathology among 18 patients.

Continue to: The pathology most frequently...

The pathology most frequently identified in the study was a meniscal tear. The mi-eye^+TM was more sensitive than MRI in identifying meniscal tears (92.6% vs 77.8%; P = .0035) and more specific in diagnosing these tears (100% vs 87.5%; P < .0002). The difference in specificity resulted from the false MRI diagnosis of a meniscal tear among 24 patients, who were found to have no tear by both mi-eye^+TM and surgical arthroscopy.

Table 1. Raw Data of mi-eye^+TM and Magnetic Resonance Imaging Findings

The second most frequent pathology was an intra-articular loose body. The mi-eye^+TM was more sensitive than MRI in identifying loose bodies (86.7% vs 20%; P = .0007). The specificity of the mi-eye^+TM and the specificity of MRI were equivalent in diagnosing loose bodies (100%). Table 1 and Table 2 show the complete set of diagnoses and associated diagnostic profiles.

Table 2. Diagnostic Profiles: Sensitivity and Specificity of mi-eye^+TM and Magnetic Resonance Imaging

^aBold P values are significant. Abbreviations: CI, confidence interval; MRI, magnetic resonance imaging; N/A, not applicable.

DISCUSSION

The overall accuracy of the mi-eye^+TM was superior to that of MRI relative to the arthroscopic gold standard in this pilot study. Other studies have demonstrated the accuracy, feasibility, and cost-efficacy of in-office arthroscopy. However, likely because of the cumbersomeness of in-office arthroscopy equipment and the potential for patient discomfort, the technique is not yet standard in the field. Recent advances in small-bore technology, digital optics, and ergonomics have addressed the difficulties associated with in-office arthroscopy, facilitating a faster and more efficient procedure. Our goal in this study was to evaluate the diagnostic capability of the mi-eye^+TM in-office arthroscopy unit, which features a small bore, digital optics, and functionality without an irrigation tower.

This study of 106 patients demonstrated equivalent or better accuracy of the mi-eye^+TM relative to MRI when compared with the gold standard of surgical arthroscopy. This was not surprising given that both the mi-eye^+TM and surgical arthroscopy are based on direct visualization of intra-articular pathology. The mi-eye^+TM unit identified more meniscal tears, intra-articular loose bodies, ACL tears, and OCD lesions than MRI did, and with enough power to demonstrate statistically significant improved sensitivity for meniscal tears and loose bodies. Furthermore, MRI demonstrated false-positive meniscal tears, ACL tears, OCD lesions, and OA, whereas the mi-eye^+TM did not demonstrate any false-positive results in comparison with surgical arthroscopy. This study demonstrated statistically significant improved specificity of the mi-eye⁺ compared with MRI in the diagnosis of meniscal tears and OA.

There are several limitations to our study. We refer to it as a pilot study because it was performed in a standard operating room. Before taking the technology to an outpatient setting, we wanted to confirm efficacy and safety in an operating room. However, the techniques used in this study are readily transferable to the outpatient clinic setting and to date have been used in more than 2000 cases.

Continue to: The specificity of MRI...

The specificity of MRI for meniscal tears was unexpectedly low compared with previous studies, which may reflect the multi-institution, multi-surgeon, multi-radiologist involvement in MRI interpretation.^4-10 MRI was performed at a variety of institutions without a standardized protocol. This lack of standardization of image capture and interpretation may have contributed to the suboptimal performance of MRI, falsely decreasing the potential ideal specificity for meniscal tears. Although this study may have underestimated the specificity of MRI for meniscal tears, we think the mi-eye^+TM and MRI results reported here reflect the findings of standard practice, without the standardization usually applied in studies. For example, a study of 139 knee MRI reports at 14 different institutions confirmed arthroscopic findings and concluded that 37% of the operations supported by a significant MRI finding were unjustified.¹¹ The authors attributed the rate of false-positive MRI findings to the wide variety of places where patients had their MRIs performed, and the subsequent variation in quality of imaging and MRI reader skill level.¹¹

Before inserting the mi-eye^+TM needle arthroscope, the surgeons had a working diagnosis of the pathology based on their clinical examination and MRI results. Clearly, this introduced a bias. Further studies will be conducted in a prospective, blinded manner to address this limitation.

Although studies of in-office arthroscopy technology date to the 1990s, there is an overall lack of data comparing in-office arthroscopy with MRI. Halbrecht and Jackson² conducted a study of 20 knee patients with both MRI and in-office needle arthroscopy. Overall, MRI was poor in detecting cartilage defects, with sensitivity of 34.6%, using the in-office arthroscopy as the confirmatory diagnosis. Although the authors did not compare in-office diagnoses with surgical arthroscopic findings, they concluded that office arthroscopy is an accurate and cost-efficient alternative to MRI in diagnostic evaluation of knee patients. Xerogeanes and colleagues¹² studied 110 patients in a prospective, blinded, multicenter trial comparing a minimally invasive office-based arthroscopy with MRI, using surgical arthroscopy as the confirmatory diagnosis. They concluded that the office-based arthroscope was statistically equivalent to diagnostic surgical arthroscopy and that it outperformed MRI in helping make accurate diagnoses. The authors applied a cost analysis to their findings and determined that office-based arthroscopy could result in an annual potential savings of $177 million for the healthcare system.¹²

Modern imaging sequences on high-Tesla MRI machines provide excellent visualization. Nevertheless, a significant number of patients do not undergo MRI, owing to time constraints, contraindications, body habitus, or anxiety/claustrophobia. Our study results confirmed that doctors treating such patients now have a viable alternative to help diagnose pathology.

CONCLUSION

The mi-eye^+TM device proved to be more sensitive and specific than MRI for intra-articular findings at the time of knee arthroscopy. Certainly there are contraindications to using the mi-eye^+TM, and our results do not obviate the need for MRI; our study did demonstrate that the mi-eye^+TM needle arthroscope can safely provide excellent visualization of intra-articular knee pathology. More studies of the mi-eye^+TM device in a clinical setting are warranted.

ABSTRACT

The use of arthroscopy for purely diagnostic purposes has been largely supplanted by noninvasive technologies, such as magnetic resonance imaging (MRI). The mi-eye^+TM (Trice Medical) technology is a small-bore needle unit for in-office arthroscopy. We conducted a pilot study comparing the mi-eye^+TM unit with MRI, using surgical arthroscopy as a gold-standard reference. We hypothesized that the mi-eye^+TM needle arthroscope, which can be used in an office setting, would be equivalent to MRI for the diagnosis of intra-articular pathology of the knee.

This prospective, multicenter, observational study was approved by the Institutional Review Board. There were 106 patients (53 males, 53 females) in the study. MRIs were interpreted by musculoskeletally trained radiologists. The study was conducted in the operating room using the mi-eye^+TM device. The mi-eye^{+ TM} device findings were compared with the MRI findings within individual pathologies, and a “per-patient” analysis was performed to compare the arthroscopic findings with those of the mi-eye^+TM and the MRI. Additionally, we identified all mi-eye^+TM findings and MRI findings that exactly matched the surgical arthroscopy findings.

The mi-eye^+TM demonstrated complete accuracy of all pathologies for 97 (91.5%) of the 106 patients included in the study, whereas MRI demonstrated complete accuracy for 65 patients (61.3%) (P < .0001). All discrepancies between mi-eye^+TM and arthroscopy were false-negative mi-eye^+TM results, as the mi-eye^+TM did not reveal some aspect of the knee’s pathology for 9 patients. The mi-eye^+TM was more sensitive than MRI in identifying meniscal tears (92.6% vs 77.8%; P = .0035) and more specific in diagnosing these tears (100% vs 41.7%; P < .0001).

The mi-eye^+TM device proved to be more sensitive and specific than MRI for intra-articular findings at time of knee arthroscopy. Certainly there are contraindications to using the mi-eye^+TM, and our results do not obviate the need for MRI, but our study did demonstrate that the mi-eye^+TM needle arthroscope can safely provide excellent visualization of intra-articular knee pathology.

Continue to: Surgical arthroscopy is the gold standard...

Surgical arthroscopy is the gold standard for the diagnosis of intra-articular knee pathologies. Nevertheless, the use of arthroscopy for purely diagnostic purposes has been largely supplanted by noninvasive technologies, such as magnetic resonance imaging (MRI). Although MRI is considered the standard diagnostic tool for acute and chronic soft-tissue injuries of the knee, its use is not without contraindication and some potential inconveniences. Contraindications to MRI are well documented. In terms of inconvenience, MRI usually requires a separate visit followed by another visit to the prescribing physician. In addition, required interpretation by a radiologist may lead to a delay in care and increase in cost.

In the early 1990s, in-office needle arthroscopy was described as a viable means of diagnosing pathologies and obtaining synovial biopsies from the knee.^1-3 Initial results were good, and the procedures had very low complication rates. Nevertheless, in-office arthroscopy of the knee is not yet widely performed, likely given concerns about the technical difficulties of in-office arthroscopy, the potential for patient discomfort, and the cumbersomeness of in-office arthroscopy units. However, significant advances have been made in the resolution capability of small-bore needle arthroscopy, resulting in much less painful procedures. Additionally, the early hardware designs, which mimicked operating room setups using towers, fluid irrigation systems, and larger arthroscopes, have been replaced with small-needle arthroscopes that use syringes for irrigation and tablet computers for visualization (Figures 1A, 1B).  

The mi-eye^+TM technology (Trice Medical) is a small-bore needle unit for in-office arthroscopy with digital optics that does not need an irrigation tower. We conducted a pilot study of the sensitivity and specificity of the mi-eye^+TM unit in comparison with MRI, using surgical arthroscopy as a gold-standard reference. We hypothesized that the mi-eye^+TM needle arthroscope, which can be used in an office setting, would be equivalent to the standard of care (MRI) for the diagnosis of intra-articular pathology of the knee.

METHODS

Central regulatory approval for this prospective, multicenter, observational study was obtained from the Western Institutional Review Board for 3 of the sites, and 1 institution required and was granted internal Institutional Review Board approval.

The study was performed by 4 sports medicine orthopedic surgeons experienced in using the mi-eye^+TM in-office arthroscope. Patients were enrolled from December 2015 through June 2016. Inclusion criteria were an indication for an arthroscopic procedure of the knee based on history, physical examination, and MRI findings. Patients were excluded from the study if there were any contraindications to completing an MRI. Acute hemarthroses of the knee or active systemic infections were also excluded. Once a patient was identified as meeting the criteria for participation, informed consent was obtained. Of the 113 patients who enrolled, 7 did not have a complete study dataset available, leaving 106 patients (53 males, 53 females) in the study. Mean age was 47 years (range, 18-82 years).

Continue to: A test result form was used...

A test result form was used to record mi-eye^+TM, surgical arthroscopy, and MRI results. This form required a “positive” or “negative” result for all of several diagnoses: medial and lateral meniscal tears, intra-articular loose body, osteoarthritis (OA), osteochondritis dissecans (OCD), and tears of the anterior and posterior cruciate ligaments (ACL, PCL). MRI was performed at a variety of imaging facilities, but the images were interpreted by musculoskeletally trained radiologists.

The study was conducted in the operating room. After the patient was appropriately anesthetized, and the extremity prepared and draped, the mi-eye^+TM procedure was performed immediately prior to surgical arthroscopy. A tourniquet was not used. At surgeon discretion, medial, lateral, or both approaches were used with the mi-eye^+TM, and diagnostic arthroscopy was performed. During the procedure, the mi-eye^+TM was advanced into the knee. Once in the synovial compartment, the external 14-gauge needle was retracted, exposing the unit’s optics. Visualization was improved by injecting normal saline through the lure lock in the mi-eye^+TM needle arthroscope. An average of 20 mL of saline was used, though the amount varied with surgeon discretion. Subsequently, the surgeon visualized structures in the knee and documented all findings.

At the end of the mi-eye^+TM procedure, the scheduled surgical arthroscopy was performed. After the surgical procedure, if there were no issues or complications, the patient was discharged from the study. No follow-up was required for the study, as arthroscopic findings served as the conclusive diagnosis for each patient, and no interventions were being studied. There were no complications related to use of the mi-eye^+TM.

The mi-eye^+TM device findings were compared with the MRI findings within individual pathologies, and a “per-patient” analysis was performed to compare the arthroscopic findings with those of the mi-eye^+TM and the MRI. Additionally, we identified all mi-eye^+TM findings and MRI findings that exactly matched the surgical arthroscopy findings. When a test had no false-positive or false-negative findings in comparison with surgical arthroscopy, it was identified as having complete accuracy for all intra-articular knee pathologies. For these methods, the 95% confidence interval was determined based on binomial distribution.

RESULTS

The mi-eye^{+ TM} demonstrated complete accuracy of all pathologies for 97 (91.5%) of the 106 patients included in the study, whereas MRI demonstrated complete accuracy for 65 patients (61.3%) (P < .0001). All discrepancies between mi-eye^+TM and surgical arthroscopy were false-negative mi-eye^+TM results, as the mi-eye^+TM did not reveal some aspect of the knee’s pathology for 9 patients. On the other hand, MRI demonstrated both false-negative and false-positive results, failing to reveal some aspect of the knee’s pathology for 31 patients, and potentially overcalling some aspect of the knee’s pathology among 18 patients.

Continue to: The pathology most frequently...

The pathology most frequently identified in the study was a meniscal tear. The mi-eye^+TM was more sensitive than MRI in identifying meniscal tears (92.6% vs 77.8%; P = .0035) and more specific in diagnosing these tears (100% vs 87.5%; P < .0002). The difference in specificity resulted from the false MRI diagnosis of a meniscal tear among 24 patients, who were found to have no tear by both mi-eye^+TM and surgical arthroscopy.

Table 1. Raw Data of mi-eye^+TM and Magnetic Resonance Imaging Findings

The second most frequent pathology was an intra-articular loose body. The mi-eye^+TM was more sensitive than MRI in identifying loose bodies (86.7% vs 20%; P = .0007). The specificity of the mi-eye^+TM and the specificity of MRI were equivalent in diagnosing loose bodies (100%). Table 1 and Table 2 show the complete set of diagnoses and associated diagnostic profiles.

Table 2. Diagnostic Profiles: Sensitivity and Specificity of mi-eye^+TM and Magnetic Resonance Imaging

^aBold P values are significant. Abbreviations: CI, confidence interval; MRI, magnetic resonance imaging; N/A, not applicable.

DISCUSSION

The overall accuracy of the mi-eye^+TM was superior to that of MRI relative to the arthroscopic gold standard in this pilot study. Other studies have demonstrated the accuracy, feasibility, and cost-efficacy of in-office arthroscopy. However, likely because of the cumbersomeness of in-office arthroscopy equipment and the potential for patient discomfort, the technique is not yet standard in the field. Recent advances in small-bore technology, digital optics, and ergonomics have addressed the difficulties associated with in-office arthroscopy, facilitating a faster and more efficient procedure. Our goal in this study was to evaluate the diagnostic capability of the mi-eye^+TM in-office arthroscopy unit, which features a small bore, digital optics, and functionality without an irrigation tower.

This study of 106 patients demonstrated equivalent or better accuracy of the mi-eye^+TM relative to MRI when compared with the gold standard of surgical arthroscopy. This was not surprising given that both the mi-eye^+TM and surgical arthroscopy are based on direct visualization of intra-articular pathology. The mi-eye^+TM unit identified more meniscal tears, intra-articular loose bodies, ACL tears, and OCD lesions than MRI did, and with enough power to demonstrate statistically significant improved sensitivity for meniscal tears and loose bodies. Furthermore, MRI demonstrated false-positive meniscal tears, ACL tears, OCD lesions, and OA, whereas the mi-eye^+TM did not demonstrate any false-positive results in comparison with surgical arthroscopy. This study demonstrated statistically significant improved specificity of the mi-eye⁺ compared with MRI in the diagnosis of meniscal tears and OA.

There are several limitations to our study. We refer to it as a pilot study because it was performed in a standard operating room. Before taking the technology to an outpatient setting, we wanted to confirm efficacy and safety in an operating room. However, the techniques used in this study are readily transferable to the outpatient clinic setting and to date have been used in more than 2000 cases.

Continue to: The specificity of MRI...

The specificity of MRI for meniscal tears was unexpectedly low compared with previous studies, which may reflect the multi-institution, multi-surgeon, multi-radiologist involvement in MRI interpretation.^4-10 MRI was performed at a variety of institutions without a standardized protocol. This lack of standardization of image capture and interpretation may have contributed to the suboptimal performance of MRI, falsely decreasing the potential ideal specificity for meniscal tears. Although this study may have underestimated the specificity of MRI for meniscal tears, we think the mi-eye^+TM and MRI results reported here reflect the findings of standard practice, without the standardization usually applied in studies. For example, a study of 139 knee MRI reports at 14 different institutions confirmed arthroscopic findings and concluded that 37% of the operations supported by a significant MRI finding were unjustified.¹¹ The authors attributed the rate of false-positive MRI findings to the wide variety of places where patients had their MRIs performed, and the subsequent variation in quality of imaging and MRI reader skill level.¹¹

Before inserting the mi-eye^+TM needle arthroscope, the surgeons had a working diagnosis of the pathology based on their clinical examination and MRI results. Clearly, this introduced a bias. Further studies will be conducted in a prospective, blinded manner to address this limitation.

Although studies of in-office arthroscopy technology date to the 1990s, there is an overall lack of data comparing in-office arthroscopy with MRI. Halbrecht and Jackson² conducted a study of 20 knee patients with both MRI and in-office needle arthroscopy. Overall, MRI was poor in detecting cartilage defects, with sensitivity of 34.6%, using the in-office arthroscopy as the confirmatory diagnosis. Although the authors did not compare in-office diagnoses with surgical arthroscopic findings, they concluded that office arthroscopy is an accurate and cost-efficient alternative to MRI in diagnostic evaluation of knee patients. Xerogeanes and colleagues¹² studied 110 patients in a prospective, blinded, multicenter trial comparing a minimally invasive office-based arthroscopy with MRI, using surgical arthroscopy as the confirmatory diagnosis. They concluded that the office-based arthroscope was statistically equivalent to diagnostic surgical arthroscopy and that it outperformed MRI in helping make accurate diagnoses. The authors applied a cost analysis to their findings and determined that office-based arthroscopy could result in an annual potential savings of $177 million for the healthcare system.¹²

Modern imaging sequences on high-Tesla MRI machines provide excellent visualization. Nevertheless, a significant number of patients do not undergo MRI, owing to time constraints, contraindications, body habitus, or anxiety/claustrophobia. Our study results confirmed that doctors treating such patients now have a viable alternative to help diagnose pathology.

CONCLUSION

The mi-eye^+TM device proved to be more sensitive and specific than MRI for intra-articular findings at the time of knee arthroscopy. Certainly there are contraindications to using the mi-eye^+TM, and our results do not obviate the need for MRI; our study did demonstrate that the mi-eye^+TM needle arthroscope can safely provide excellent visualization of intra-articular knee pathology. More studies of the mi-eye^+TM device in a clinical setting are warranted.

Over the past few decades, there has been a dramatic increase in the number of shoulder arthroplasties performed around the world. This increase is the result of an aging and increasingly more active population, better implant technology, and the advent of reverse shoulder arthroplasty (RSA) for rotator cuff arthropathy. Additionally, as the indications for RSA have expanded to include pathologies such as rotator cuff insufficiency, chronic instabilities, trauma, and tumors, the number of arthroplasties will continue to increase. Although the results of most arthroplasties are good and predictable, any glenoid and/or humeral bone deficiencies can have detrimental effects on the clinical outcomes of these procedures. Bone loss becomes more of a problem in revision cases, and, as the number of primary arthroplasties increases, it follows that the number of revision procedures will also increase.

Many of the disease- or procedure-specific processes indicated for shoulder arthroplasty have predictable patterns of bone loss, especially on the glenoid side. Walch and colleagues¹ and Bercik and colleagues² made us aware that many patients with primary osteoarthritis have significant glenoid bone deformity. Similarly, there have been a number of first- and second-generation classification systems for delineating glenoid deformity in rotator cuff tear arthropathy and in revision settings. In revision settings, both glenoid and humeral bone deficiencies can occur as a result of implant removal, iatrogenic fracture, and even infection. Each of these bone loss patterns must be recognized and treated appropriately for the best surgical outcome.

The articles in this month of The American Journal of Orthopedics address the most up-to-date concepts and solutions regarding both humeral and glenoid bone loss in shoulder arthroplasty of all types.

HUMERAL BONE LOSS

Humeral bone loss is typically encountered in proximal humerus fractures, in revision surgery necessitating humeral component removal, and, less commonly, in tumors and infection.

In many displaced proximal humeral fractures indicated for shoulder arthroplasty, the bone is comminuted with displacement of the lesser and greater tuberosities. In these situations, failure of tuberosity healing may result in loss of rotator cuff function with loss of elevation, rotation, and even instability. Humeral shortening can also occur as a result of bone loss and can compromise deltoid function by loss of proper muscle tension, leading to instability, dysfunction, or both. In addition to possible instability, humeral shortening with metaphyseal bone loss can adversely affect long-term fixation of the humeral component, leading to stem loosening or failure. Cuff and colleagues³ showed significantly more rotational micromotion in cases lacking metaphyseal support, leading to aseptic loosening of the humeral stem.

Humeral bone loss can also result from humeral stem component removal in revision shoulder arthroplasty for infection, component failure or loosening, and even periprosthetic fracture resulting from surgery or trauma.

For the surgeon, humeral bone loss can create a complex set of circumstances related to rotator cuff attachment failure, soft-tissue balancing effects, and component fixation issues. Any such issue must be recognized and addressed for best outcomes. Best results can be obtained with preoperative imaging, planning, use of bone graft techniques, proximal humeral allografts, and, more recently, modular and patient-specific implants. All of these issues are discussed comprehensively in the articles this month.

Continue to: GLENOID BONE LOSS

Proper glenoid component placement with durable fixation is crucial for success in anatomical total shoulder arthroplasty and RSA. Glenoid bone deformity and loss can result from intrinsic deformity characteristics seen in primary osteoarthritis, cuff tear arthropathy, or glenoid component removal in revision situations and infection. These bone deformity complications can be extremely difficult to treat and in some cases lead to catastrophic failure of the index arthroplasty.

We are now aware that one key to success in the face of moderate to severe deformity is proper recognition. Newer imaging techniques, including 2-dimensional (2-D) computed tomography (CT) and 3-dimensional (3-D) modeling and surgical planning software tools, which are outlined in an upcoming article, have given surgeons important new instruments that can help in treating these difficult cases.

Glenoid bone deformity in primary osteoarthritis was well delineated in the 1999 seminal study of CT changes by Walch and colleagues.¹ The Walch classification system, which characterized glenoid morphology based on 2-D CT findings, was recently upgraded, based on 3-D imaging technology, to include Walch B3 and D patterns (Figure 1).² Recognition of certain primary deformities in osteoarthritis has led to increased use of RSA in some cases of Walch B2, B3, and C deformities with substantial glenoid retroversion and/or humeral head subluxation.⁴

In cases of rotator cuff tear arthropathy, glenoid bone deformities are well described with several classification systems based on degree and dimension of bone insufficiency. The Hamada classification system defines the degree of medial glenoid erosion and superior bone loss, as well as acetabularization of the acromion in 5 grades; ⁵ Rispoli and colleagues⁶ defined and graded the degree of medicalization of the glenohumeral joint based on degree of subchondral plate erosion; and Visotsky and colleagues⁷ based their classification system on wear patterns of bone loss, alignment, and concomitant soft-tissue insufficiencies leading to instability and rotation loss.

In severe glenoid bone deficiency after glenoid component removal, Antuna and colleagues⁸ described the classic findings related to medial bone loss, anterior and posterior wall failure, and combinations thereof.

Continue to: All these classification systems...

All these classification systems are based on the 2-D appearance of the glenoid and should be considered cautiously. The glenoid is a complex 3-D structure that can be affected by any number of disease processes, trauma, and surgical intervention. Using more modern CT techniques and 3-D imaging, we now know that many deformities previously classified as unidirectional are, instead, complex and multidirectional.

Frankle and colleagues⁹ developed a classification based more 3-D CT models which has further classified severe glenoid vault deformities in relation to direction and degree of bone loss (Figures 2A-2E). Using this system, they were better able to determine degree and direction of deformity than in previous 2-D evaluations, and they were able to determine the amount of glenoid vault bone available for baseplate fixation. Scalise and colleagues¹⁰ further defined the influence of such 3-D planning in total shoulder arthroplasty.

With knowledge of these classification systems and use of contemporary imaging systems, shoulder arthroplasty in cases of severe glenoid deficiency can be more successful. Potentially, we can improve outcomes even more in the more severe cases of bone loss with use of patient-specific planning tools, including the guides and patient-specific implants that are now readily available with many implant systems.¹¹

Preoperative planning tools, bone-grafting techniques, augmented and specialized glenoid and humeral implants, and patient-specific implants are discussed this month to give our readers a comprehensive review of the latest concepts in shoulder arthroplasty in cases of significant bone loss or deformity.

This month of The American Journal of Orthopedics presents the most current and cutting-edge solutions for humeral and glenoid bone deformities and deficiencies in contemporary shoulder arthroplasties.

Over the past few decades, there has been a dramatic increase in the number of shoulder arthroplasties performed around the world. This increase is the result of an aging and increasingly more active population, better implant technology, and the advent of reverse shoulder arthroplasty (RSA) for rotator cuff arthropathy. Additionally, as the indications for RSA have expanded to include pathologies such as rotator cuff insufficiency, chronic instabilities, trauma, and tumors, the number of arthroplasties will continue to increase. Although the results of most arthroplasties are good and predictable, any glenoid and/or humeral bone deficiencies can have detrimental effects on the clinical outcomes of these procedures. Bone loss becomes more of a problem in revision cases, and, as the number of primary arthroplasties increases, it follows that the number of revision procedures will also increase.

Many of the disease- or procedure-specific processes indicated for shoulder arthroplasty have predictable patterns of bone loss, especially on the glenoid side. Walch and colleagues¹ and Bercik and colleagues² made us aware that many patients with primary osteoarthritis have significant glenoid bone deformity. Similarly, there have been a number of first- and second-generation classification systems for delineating glenoid deformity in rotator cuff tear arthropathy and in revision settings. In revision settings, both glenoid and humeral bone deficiencies can occur as a result of implant removal, iatrogenic fracture, and even infection. Each of these bone loss patterns must be recognized and treated appropriately for the best surgical outcome.

The articles in this month of The American Journal of Orthopedics address the most up-to-date concepts and solutions regarding both humeral and glenoid bone loss in shoulder arthroplasty of all types.

HUMERAL BONE LOSS

Humeral bone loss is typically encountered in proximal humerus fractures, in revision surgery necessitating humeral component removal, and, less commonly, in tumors and infection.

In many displaced proximal humeral fractures indicated for shoulder arthroplasty, the bone is comminuted with displacement of the lesser and greater tuberosities. In these situations, failure of tuberosity healing may result in loss of rotator cuff function with loss of elevation, rotation, and even instability. Humeral shortening can also occur as a result of bone loss and can compromise deltoid function by loss of proper muscle tension, leading to instability, dysfunction, or both. In addition to possible instability, humeral shortening with metaphyseal bone loss can adversely affect long-term fixation of the humeral component, leading to stem loosening or failure. Cuff and colleagues³ showed significantly more rotational micromotion in cases lacking metaphyseal support, leading to aseptic loosening of the humeral stem.

Humeral bone loss can also result from humeral stem component removal in revision shoulder arthroplasty for infection, component failure or loosening, and even periprosthetic fracture resulting from surgery or trauma.

For the surgeon, humeral bone loss can create a complex set of circumstances related to rotator cuff attachment failure, soft-tissue balancing effects, and component fixation issues. Any such issue must be recognized and addressed for best outcomes. Best results can be obtained with preoperative imaging, planning, use of bone graft techniques, proximal humeral allografts, and, more recently, modular and patient-specific implants. All of these issues are discussed comprehensively in the articles this month.

Continue to: GLENOID BONE LOSS

Proper glenoid component placement with durable fixation is crucial for success in anatomical total shoulder arthroplasty and RSA. Glenoid bone deformity and loss can result from intrinsic deformity characteristics seen in primary osteoarthritis, cuff tear arthropathy, or glenoid component removal in revision situations and infection. These bone deformity complications can be extremely difficult to treat and in some cases lead to catastrophic failure of the index arthroplasty.

We are now aware that one key to success in the face of moderate to severe deformity is proper recognition. Newer imaging techniques, including 2-dimensional (2-D) computed tomography (CT) and 3-dimensional (3-D) modeling and surgical planning software tools, which are outlined in an upcoming article, have given surgeons important new instruments that can help in treating these difficult cases.

Glenoid bone deformity in primary osteoarthritis was well delineated in the 1999 seminal study of CT changes by Walch and colleagues.¹ The Walch classification system, which characterized glenoid morphology based on 2-D CT findings, was recently upgraded, based on 3-D imaging technology, to include Walch B3 and D patterns (Figure 1).² Recognition of certain primary deformities in osteoarthritis has led to increased use of RSA in some cases of Walch B2, B3, and C deformities with substantial glenoid retroversion and/or humeral head subluxation.⁴

In cases of rotator cuff tear arthropathy, glenoid bone deformities are well described with several classification systems based on degree and dimension of bone insufficiency. The Hamada classification system defines the degree of medial glenoid erosion and superior bone loss, as well as acetabularization of the acromion in 5 grades; ⁵ Rispoli and colleagues⁶ defined and graded the degree of medicalization of the glenohumeral joint based on degree of subchondral plate erosion; and Visotsky and colleagues⁷ based their classification system on wear patterns of bone loss, alignment, and concomitant soft-tissue insufficiencies leading to instability and rotation loss.

In severe glenoid bone deficiency after glenoid component removal, Antuna and colleagues⁸ described the classic findings related to medial bone loss, anterior and posterior wall failure, and combinations thereof.

Continue to: All these classification systems...

All these classification systems are based on the 2-D appearance of the glenoid and should be considered cautiously. The glenoid is a complex 3-D structure that can be affected by any number of disease processes, trauma, and surgical intervention. Using more modern CT techniques and 3-D imaging, we now know that many deformities previously classified as unidirectional are, instead, complex and multidirectional.

Frankle and colleagues⁹ developed a classification based more 3-D CT models which has further classified severe glenoid vault deformities in relation to direction and degree of bone loss (Figures 2A-2E). Using this system, they were better able to determine degree and direction of deformity than in previous 2-D evaluations, and they were able to determine the amount of glenoid vault bone available for baseplate fixation. Scalise and colleagues¹⁰ further defined the influence of such 3-D planning in total shoulder arthroplasty.

With knowledge of these classification systems and use of contemporary imaging systems, shoulder arthroplasty in cases of severe glenoid deficiency can be more successful. Potentially, we can improve outcomes even more in the more severe cases of bone loss with use of patient-specific planning tools, including the guides and patient-specific implants that are now readily available with many implant systems.¹¹

Preoperative planning tools, bone-grafting techniques, augmented and specialized glenoid and humeral implants, and patient-specific implants are discussed this month to give our readers a comprehensive review of the latest concepts in shoulder arthroplasty in cases of significant bone loss or deformity.

This month of The American Journal of Orthopedics presents the most current and cutting-edge solutions for humeral and glenoid bone deformities and deficiencies in contemporary shoulder arthroplasties.

Over the past few decades, there has been a dramatic increase in the number of shoulder arthroplasties performed around the world. This increase is the result of an aging and increasingly more active population, better implant technology, and the advent of reverse shoulder arthroplasty (RSA) for rotator cuff arthropathy. Additionally, as the indications for RSA have expanded to include pathologies such as rotator cuff insufficiency, chronic instabilities, trauma, and tumors, the number of arthroplasties will continue to increase. Although the results of most arthroplasties are good and predictable, any glenoid and/or humeral bone deficiencies can have detrimental effects on the clinical outcomes of these procedures. Bone loss becomes more of a problem in revision cases, and, as the number of primary arthroplasties increases, it follows that the number of revision procedures will also increase.

Many of the disease- or procedure-specific processes indicated for shoulder arthroplasty have predictable patterns of bone loss, especially on the glenoid side. Walch and colleagues¹ and Bercik and colleagues² made us aware that many patients with primary osteoarthritis have significant glenoid bone deformity. Similarly, there have been a number of first- and second-generation classification systems for delineating glenoid deformity in rotator cuff tear arthropathy and in revision settings. In revision settings, both glenoid and humeral bone deficiencies can occur as a result of implant removal, iatrogenic fracture, and even infection. Each of these bone loss patterns must be recognized and treated appropriately for the best surgical outcome.

The articles in this month of The American Journal of Orthopedics address the most up-to-date concepts and solutions regarding both humeral and glenoid bone loss in shoulder arthroplasty of all types.

HUMERAL BONE LOSS

Humeral bone loss is typically encountered in proximal humerus fractures, in revision surgery necessitating humeral component removal, and, less commonly, in tumors and infection.

In many displaced proximal humeral fractures indicated for shoulder arthroplasty, the bone is comminuted with displacement of the lesser and greater tuberosities. In these situations, failure of tuberosity healing may result in loss of rotator cuff function with loss of elevation, rotation, and even instability. Humeral shortening can also occur as a result of bone loss and can compromise deltoid function by loss of proper muscle tension, leading to instability, dysfunction, or both. In addition to possible instability, humeral shortening with metaphyseal bone loss can adversely affect long-term fixation of the humeral component, leading to stem loosening or failure. Cuff and colleagues³ showed significantly more rotational micromotion in cases lacking metaphyseal support, leading to aseptic loosening of the humeral stem.

Humeral bone loss can also result from humeral stem component removal in revision shoulder arthroplasty for infection, component failure or loosening, and even periprosthetic fracture resulting from surgery or trauma.

For the surgeon, humeral bone loss can create a complex set of circumstances related to rotator cuff attachment failure, soft-tissue balancing effects, and component fixation issues. Any such issue must be recognized and addressed for best outcomes. Best results can be obtained with preoperative imaging, planning, use of bone graft techniques, proximal humeral allografts, and, more recently, modular and patient-specific implants. All of these issues are discussed comprehensively in the articles this month.

Continue to: GLENOID BONE LOSS

Proper glenoid component placement with durable fixation is crucial for success in anatomical total shoulder arthroplasty and RSA. Glenoid bone deformity and loss can result from intrinsic deformity characteristics seen in primary osteoarthritis, cuff tear arthropathy, or glenoid component removal in revision situations and infection. These bone deformity complications can be extremely difficult to treat and in some cases lead to catastrophic failure of the index arthroplasty.

We are now aware that one key to success in the face of moderate to severe deformity is proper recognition. Newer imaging techniques, including 2-dimensional (2-D) computed tomography (CT) and 3-dimensional (3-D) modeling and surgical planning software tools, which are outlined in an upcoming article, have given surgeons important new instruments that can help in treating these difficult cases.

Glenoid bone deformity in primary osteoarthritis was well delineated in the 1999 seminal study of CT changes by Walch and colleagues.¹ The Walch classification system, which characterized glenoid morphology based on 2-D CT findings, was recently upgraded, based on 3-D imaging technology, to include Walch B3 and D patterns (Figure 1).² Recognition of certain primary deformities in osteoarthritis has led to increased use of RSA in some cases of Walch B2, B3, and C deformities with substantial glenoid retroversion and/or humeral head subluxation.⁴

In cases of rotator cuff tear arthropathy, glenoid bone deformities are well described with several classification systems based on degree and dimension of bone insufficiency. The Hamada classification system defines the degree of medial glenoid erosion and superior bone loss, as well as acetabularization of the acromion in 5 grades; ⁵ Rispoli and colleagues⁶ defined and graded the degree of medicalization of the glenohumeral joint based on degree of subchondral plate erosion; and Visotsky and colleagues⁷ based their classification system on wear patterns of bone loss, alignment, and concomitant soft-tissue insufficiencies leading to instability and rotation loss.

In severe glenoid bone deficiency after glenoid component removal, Antuna and colleagues⁸ described the classic findings related to medial bone loss, anterior and posterior wall failure, and combinations thereof.

Continue to: All these classification systems...

All these classification systems are based on the 2-D appearance of the glenoid and should be considered cautiously. The glenoid is a complex 3-D structure that can be affected by any number of disease processes, trauma, and surgical intervention. Using more modern CT techniques and 3-D imaging, we now know that many deformities previously classified as unidirectional are, instead, complex and multidirectional.

Frankle and colleagues⁹ developed a classification based more 3-D CT models which has further classified severe glenoid vault deformities in relation to direction and degree of bone loss (Figures 2A-2E). Using this system, they were better able to determine degree and direction of deformity than in previous 2-D evaluations, and they were able to determine the amount of glenoid vault bone available for baseplate fixation. Scalise and colleagues¹⁰ further defined the influence of such 3-D planning in total shoulder arthroplasty.

With knowledge of these classification systems and use of contemporary imaging systems, shoulder arthroplasty in cases of severe glenoid deficiency can be more successful. Potentially, we can improve outcomes even more in the more severe cases of bone loss with use of patient-specific planning tools, including the guides and patient-specific implants that are now readily available with many implant systems.¹¹

Preoperative planning tools, bone-grafting techniques, augmented and specialized glenoid and humeral implants, and patient-specific implants are discussed this month to give our readers a comprehensive review of the latest concepts in shoulder arthroplasty in cases of significant bone loss or deformity.

This month of The American Journal of Orthopedics presents the most current and cutting-edge solutions for humeral and glenoid bone deformities and deficiencies in contemporary shoulder arthroplasties.

Take-Home Points

• With more shoulder arthroplasties being performed on younger patients, we can expect more revisions in the future.
• Many of these revision cases will have profound glenoid bone loss.
• Bone grafting the glenoid defects in shoulder arthroplasty has been less successful especially with significant vault defects.
• Based on the CAD-CAM success in total hip and knee replacement surgery, a patient-specific glenoid vault reconstruction system has been developed by Zimmer Biomet to deal with profound glenoid bone loss and cuff insufficiency.
• Early results of this vault reconstruction system have been promising in these most difficult clinical situations.

Early results of this vault reconstruction system have been promising in these most difficult clinical situations. Complex glenoid deformities present the most difficult challenges in shoulder arthroplasty (SA). These deformities may be caused by severe degenerative or congenital deformity, posttraumatic anatomy, tumor, or, in most cases, bone loss after glenoid failure in anatomical total SA.

Walch and colleagues¹ described the pathologic glenoid lesions seen in progressive degenerative arthritis and some congenital defects. The most severe were initially characterized as Walch B2 and Walch C deformities. These lesions have been further classified to include Walch B3 posteroinferior glenoid deformities.^2,3 Each of these deformities can result in severe glenoid vault deficiency.

In some revision cases and in severe rheumatoid cases, these deformities can present as cavitary lesions with or without failure of the glenoid rim or wall resulting in significant compromise of glenoid vault lesions.^4,5 In these cases, the degree of “medialization” of the native glenohumeral joint line and the amount of peripheral bone loss can have profound effects on the amount of bone available for fixation and on the ability to allow component positioning for best surgical and biomechanical outcomes.

Other bone loss deformities, which have been described by Antuna and colleagues⁶ and Seebauer and colleagues,⁷ often accompany disease processes with severe cuff deficiency. These deformities historically have been treated with intercalary-type bone grafts in 1- or 2-stage revision of reverse SA or in salvage to hemiarthroplasty. Treatment of these pathologies with the technique described produced only fair results in short-term to midterm follow-up. The most commonly reported complications have been component loosening, bone graft failure, infection, and instability.^8-11Borrowing from hip and knee arthroplasty surgeons’ experience in using CAD/CAM (computer-aided design/computer-aided manufacturing) patient-specific implants to fill significant bony defects, Dr. D. M. Dines and Dr. Craig developed a patient-specific glenoid vault reconstruction system (VRS) in conjunction with the Comprehensive Shoulder Arthroplasty System (Zimmer Biomet). For a number of years, the Food and Drug Administration allowed this patient-specific glenoid VRS component to be made available only as a custom implant. Recently, however, full 510K clearance was granted to use the VRS in reverse SA patients with severe soft-tissue deficiency and significant glenoid bone loss.

In this article, we describe the implant and its indications, technical aspects of production, and surgical technique.

Vault Reconstruction System

Severe glenoid bone loss often requires an implant that specifically matches the patient’s anatomy. The patient-specific glenoid VRS (Figure 1) is made from a 3-dimensional reconstruction of a 2-dimensional computed tomography image.

In some cases in which the bone is sufficient to enhance fixation in the deficient glenoid vault, a custom boss may be added to the implant, as well as a custom guide matching the implant.

Glenoid Exposure

In most cases of severe glenoid bone loss, the associated soft-tissue deficiency allows for easier glenoid exposure. In this implant system, however, maximal peripheral en face exposure of the glenoid is required. In addition, it is mandatory to avoid disturbing the remaining glenoid bone surfaces, which often are thin or fragile, because the patient-specific implant is referenced to this anatomy. Bone that is not maintained changes the orientation of the patient-specific guide and ultimately the fixation of the component. Using the correct retractors and meticulously excising soft-tissue scar tissue are crucial for success.

Implant Positioning

With the glenoid surface properly exposed, the removable inserter handle and the built-in lip on the implant are used to position the patient-specific guide. Next, a central guide pin is placed through the inserter for temporary fixation and further instrumentation. If enough bone is present, a boss reamer can be used over the guide pin to prepare and increase the fixation surface.

The central 6.5-mm nonlocking compression screw is placed to provide strong initial compressive fixation in best bone.

Case Examples

A 49-year-old man underwent hemiarthroplasty for osteoarthritis. The procedure failed and, 3 years later, was revised to conventional total SA. Unfortunately, the cemented all-polyethylene glenoid loosened secondary to active Propionibacterium acnes infection, which required excisional arthroplasty with antibiotic spacer. Significant cavitary bone loss was found with anterior glenoid wall bone loss compromising the glenoid vault. Given the history of bone loss and infection, patient-specific glenoid vault reconstruction was performed after infection eradication. Within 4 years after this surgery, the patient had resumed all activities. At age 57 years, he had restricted active forward elevation and abduction to 120° but was satisfied with the outcome.

A 71-year-old man underwent reverse SA for rotator cuff-deficient osteoarthritis. After implant excision and spacer placement, he was left with severe soft-tissue deficiency and glenoid bone loss, which caused substantial disability. After treatment for infection, a work-up was performed for glenoid bone deficiency and insertion of a patient-specific glenoid VRS implant.

Discussion

Glenoid bone deformity and deficiency are among the most difficult challenges in SA—a particularly compelling fact given the increasing number of SAs being performed in younger, more active patients. SA surgeons can now expect to be performing even more revisions with concomitant bone defects, which may be severe in some cases.

In addition to these causes of extreme bone loss, recent awareness of the importance of recognizing and treating bone deficits in osteoarthritis, rheumatoid arthritis, trauma, and instability has led to the development of patient-specific guides, instrumentation, and implants. Concepts from the use of CAD/CAM acetabular implants in total hip arthroplasty for severe acetabular bony defects were applied to the use of patient-specific glenoid reconstruction implants without bone graft augmentation.¹² In different form, this idea was reported by Chammaa and colleagues¹³ in 30 cases, and clinical and durable results were very promising.

We have described use of this technique in 2 extreme cases of glenoid vault deficiency. In each case, short-term results were quite satisfactory. However, both patients were relatively young, and long-term clinical and radiographic follow-up is needed.

Many of the severe cases of glenoid bone loss require an implant that specifically matches the patient’s anatomy. The glenoid VRS implant described here may be of great benefit in these difficult reconstructions and is a valuable addition to the armamentarium of treatments for distorted glenoid anatomy. Eventually, the idea may become useful in treating other, less significant defects by re-creating more-normal biomechanics in SA without bone graft.

Am J Orthop. 2017;46(2):104-108. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• With more shoulder arthroplasties being performed on younger patients, we can expect more revisions in the future.
• Many of these revision cases will have profound glenoid bone loss.
• Bone grafting the glenoid defects in shoulder arthroplasty has been less successful especially with significant vault defects.
• Based on the CAD-CAM success in total hip and knee replacement surgery, a patient-specific glenoid vault reconstruction system has been developed by Zimmer Biomet to deal with profound glenoid bone loss and cuff insufficiency.
• Early results of this vault reconstruction system have been promising in these most difficult clinical situations.

Early results of this vault reconstruction system have been promising in these most difficult clinical situations. Complex glenoid deformities present the most difficult challenges in shoulder arthroplasty (SA). These deformities may be caused by severe degenerative or congenital deformity, posttraumatic anatomy, tumor, or, in most cases, bone loss after glenoid failure in anatomical total SA.

Walch and colleagues¹ described the pathologic glenoid lesions seen in progressive degenerative arthritis and some congenital defects. The most severe were initially characterized as Walch B2 and Walch C deformities. These lesions have been further classified to include Walch B3 posteroinferior glenoid deformities.^2,3 Each of these deformities can result in severe glenoid vault deficiency.

In some revision cases and in severe rheumatoid cases, these deformities can present as cavitary lesions with or without failure of the glenoid rim or wall resulting in significant compromise of glenoid vault lesions.^4,5 In these cases, the degree of “medialization” of the native glenohumeral joint line and the amount of peripheral bone loss can have profound effects on the amount of bone available for fixation and on the ability to allow component positioning for best surgical and biomechanical outcomes.

Other bone loss deformities, which have been described by Antuna and colleagues⁶ and Seebauer and colleagues,⁷ often accompany disease processes with severe cuff deficiency. These deformities historically have been treated with intercalary-type bone grafts in 1- or 2-stage revision of reverse SA or in salvage to hemiarthroplasty. Treatment of these pathologies with the technique described produced only fair results in short-term to midterm follow-up. The most commonly reported complications have been component loosening, bone graft failure, infection, and instability.^8-11Borrowing from hip and knee arthroplasty surgeons’ experience in using CAD/CAM (computer-aided design/computer-aided manufacturing) patient-specific implants to fill significant bony defects, Dr. D. M. Dines and Dr. Craig developed a patient-specific glenoid vault reconstruction system (VRS) in conjunction with the Comprehensive Shoulder Arthroplasty System (Zimmer Biomet). For a number of years, the Food and Drug Administration allowed this patient-specific glenoid VRS component to be made available only as a custom implant. Recently, however, full 510K clearance was granted to use the VRS in reverse SA patients with severe soft-tissue deficiency and significant glenoid bone loss.

In this article, we describe the implant and its indications, technical aspects of production, and surgical technique.

Vault Reconstruction System

Severe glenoid bone loss often requires an implant that specifically matches the patient’s anatomy. The patient-specific glenoid VRS (Figure 1) is made from a 3-dimensional reconstruction of a 2-dimensional computed tomography image.

In some cases in which the bone is sufficient to enhance fixation in the deficient glenoid vault, a custom boss may be added to the implant, as well as a custom guide matching the implant.

Glenoid Exposure

In most cases of severe glenoid bone loss, the associated soft-tissue deficiency allows for easier glenoid exposure. In this implant system, however, maximal peripheral en face exposure of the glenoid is required. In addition, it is mandatory to avoid disturbing the remaining glenoid bone surfaces, which often are thin or fragile, because the patient-specific implant is referenced to this anatomy. Bone that is not maintained changes the orientation of the patient-specific guide and ultimately the fixation of the component. Using the correct retractors and meticulously excising soft-tissue scar tissue are crucial for success.

Implant Positioning

With the glenoid surface properly exposed, the removable inserter handle and the built-in lip on the implant are used to position the patient-specific guide. Next, a central guide pin is placed through the inserter for temporary fixation and further instrumentation. If enough bone is present, a boss reamer can be used over the guide pin to prepare and increase the fixation surface.

The central 6.5-mm nonlocking compression screw is placed to provide strong initial compressive fixation in best bone.

Case Examples

A 49-year-old man underwent hemiarthroplasty for osteoarthritis. The procedure failed and, 3 years later, was revised to conventional total SA. Unfortunately, the cemented all-polyethylene glenoid loosened secondary to active Propionibacterium acnes infection, which required excisional arthroplasty with antibiotic spacer. Significant cavitary bone loss was found with anterior glenoid wall bone loss compromising the glenoid vault. Given the history of bone loss and infection, patient-specific glenoid vault reconstruction was performed after infection eradication. Within 4 years after this surgery, the patient had resumed all activities. At age 57 years, he had restricted active forward elevation and abduction to 120° but was satisfied with the outcome.

A 71-year-old man underwent reverse SA for rotator cuff-deficient osteoarthritis. After implant excision and spacer placement, he was left with severe soft-tissue deficiency and glenoid bone loss, which caused substantial disability. After treatment for infection, a work-up was performed for glenoid bone deficiency and insertion of a patient-specific glenoid VRS implant.

Discussion

Glenoid bone deformity and deficiency are among the most difficult challenges in SA—a particularly compelling fact given the increasing number of SAs being performed in younger, more active patients. SA surgeons can now expect to be performing even more revisions with concomitant bone defects, which may be severe in some cases.

In addition to these causes of extreme bone loss, recent awareness of the importance of recognizing and treating bone deficits in osteoarthritis, rheumatoid arthritis, trauma, and instability has led to the development of patient-specific guides, instrumentation, and implants. Concepts from the use of CAD/CAM acetabular implants in total hip arthroplasty for severe acetabular bony defects were applied to the use of patient-specific glenoid reconstruction implants without bone graft augmentation.¹² In different form, this idea was reported by Chammaa and colleagues¹³ in 30 cases, and clinical and durable results were very promising.

We have described use of this technique in 2 extreme cases of glenoid vault deficiency. In each case, short-term results were quite satisfactory. However, both patients were relatively young, and long-term clinical and radiographic follow-up is needed.

Many of the severe cases of glenoid bone loss require an implant that specifically matches the patient’s anatomy. The glenoid VRS implant described here may be of great benefit in these difficult reconstructions and is a valuable addition to the armamentarium of treatments for distorted glenoid anatomy. Eventually, the idea may become useful in treating other, less significant defects by re-creating more-normal biomechanics in SA without bone graft.

Am J Orthop. 2017;46(2):104-108. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• With more shoulder arthroplasties being performed on younger patients, we can expect more revisions in the future.
• Many of these revision cases will have profound glenoid bone loss.
• Bone grafting the glenoid defects in shoulder arthroplasty has been less successful especially with significant vault defects.
• Based on the CAD-CAM success in total hip and knee replacement surgery, a patient-specific glenoid vault reconstruction system has been developed by Zimmer Biomet to deal with profound glenoid bone loss and cuff insufficiency.
• Early results of this vault reconstruction system have been promising in these most difficult clinical situations.

Early results of this vault reconstruction system have been promising in these most difficult clinical situations. Complex glenoid deformities present the most difficult challenges in shoulder arthroplasty (SA). These deformities may be caused by severe degenerative or congenital deformity, posttraumatic anatomy, tumor, or, in most cases, bone loss after glenoid failure in anatomical total SA.

Walch and colleagues¹ described the pathologic glenoid lesions seen in progressive degenerative arthritis and some congenital defects. The most severe were initially characterized as Walch B2 and Walch C deformities. These lesions have been further classified to include Walch B3 posteroinferior glenoid deformities.^2,3 Each of these deformities can result in severe glenoid vault deficiency.

In some revision cases and in severe rheumatoid cases, these deformities can present as cavitary lesions with or without failure of the glenoid rim or wall resulting in significant compromise of glenoid vault lesions.^4,5 In these cases, the degree of “medialization” of the native glenohumeral joint line and the amount of peripheral bone loss can have profound effects on the amount of bone available for fixation and on the ability to allow component positioning for best surgical and biomechanical outcomes.

Other bone loss deformities, which have been described by Antuna and colleagues⁶ and Seebauer and colleagues,⁷ often accompany disease processes with severe cuff deficiency. These deformities historically have been treated with intercalary-type bone grafts in 1- or 2-stage revision of reverse SA or in salvage to hemiarthroplasty. Treatment of these pathologies with the technique described produced only fair results in short-term to midterm follow-up. The most commonly reported complications have been component loosening, bone graft failure, infection, and instability.^8-11Borrowing from hip and knee arthroplasty surgeons’ experience in using CAD/CAM (computer-aided design/computer-aided manufacturing) patient-specific implants to fill significant bony defects, Dr. D. M. Dines and Dr. Craig developed a patient-specific glenoid vault reconstruction system (VRS) in conjunction with the Comprehensive Shoulder Arthroplasty System (Zimmer Biomet). For a number of years, the Food and Drug Administration allowed this patient-specific glenoid VRS component to be made available only as a custom implant. Recently, however, full 510K clearance was granted to use the VRS in reverse SA patients with severe soft-tissue deficiency and significant glenoid bone loss.

In this article, we describe the implant and its indications, technical aspects of production, and surgical technique.

Vault Reconstruction System

Severe glenoid bone loss often requires an implant that specifically matches the patient’s anatomy. The patient-specific glenoid VRS (Figure 1) is made from a 3-dimensional reconstruction of a 2-dimensional computed tomography image.

In some cases in which the bone is sufficient to enhance fixation in the deficient glenoid vault, a custom boss may be added to the implant, as well as a custom guide matching the implant.

Glenoid Exposure

In most cases of severe glenoid bone loss, the associated soft-tissue deficiency allows for easier glenoid exposure. In this implant system, however, maximal peripheral en face exposure of the glenoid is required. In addition, it is mandatory to avoid disturbing the remaining glenoid bone surfaces, which often are thin or fragile, because the patient-specific implant is referenced to this anatomy. Bone that is not maintained changes the orientation of the patient-specific guide and ultimately the fixation of the component. Using the correct retractors and meticulously excising soft-tissue scar tissue are crucial for success.

Implant Positioning

With the glenoid surface properly exposed, the removable inserter handle and the built-in lip on the implant are used to position the patient-specific guide. Next, a central guide pin is placed through the inserter for temporary fixation and further instrumentation. If enough bone is present, a boss reamer can be used over the guide pin to prepare and increase the fixation surface.

The central 6.5-mm nonlocking compression screw is placed to provide strong initial compressive fixation in best bone.

Case Examples

A 49-year-old man underwent hemiarthroplasty for osteoarthritis. The procedure failed and, 3 years later, was revised to conventional total SA. Unfortunately, the cemented all-polyethylene glenoid loosened secondary to active Propionibacterium acnes infection, which required excisional arthroplasty with antibiotic spacer. Significant cavitary bone loss was found with anterior glenoid wall bone loss compromising the glenoid vault. Given the history of bone loss and infection, patient-specific glenoid vault reconstruction was performed after infection eradication. Within 4 years after this surgery, the patient had resumed all activities. At age 57 years, he had restricted active forward elevation and abduction to 120° but was satisfied with the outcome.

A 71-year-old man underwent reverse SA for rotator cuff-deficient osteoarthritis. After implant excision and spacer placement, he was left with severe soft-tissue deficiency and glenoid bone loss, which caused substantial disability. After treatment for infection, a work-up was performed for glenoid bone deficiency and insertion of a patient-specific glenoid VRS implant.

Discussion

Glenoid bone deformity and deficiency are among the most difficult challenges in SA—a particularly compelling fact given the increasing number of SAs being performed in younger, more active patients. SA surgeons can now expect to be performing even more revisions with concomitant bone defects, which may be severe in some cases.

In addition to these causes of extreme bone loss, recent awareness of the importance of recognizing and treating bone deficits in osteoarthritis, rheumatoid arthritis, trauma, and instability has led to the development of patient-specific guides, instrumentation, and implants. Concepts from the use of CAD/CAM acetabular implants in total hip arthroplasty for severe acetabular bony defects were applied to the use of patient-specific glenoid reconstruction implants without bone graft augmentation.¹² In different form, this idea was reported by Chammaa and colleagues¹³ in 30 cases, and clinical and durable results were very promising.

We have described use of this technique in 2 extreme cases of glenoid vault deficiency. In each case, short-term results were quite satisfactory. However, both patients were relatively young, and long-term clinical and radiographic follow-up is needed.

Many of the severe cases of glenoid bone loss require an implant that specifically matches the patient’s anatomy. The glenoid VRS implant described here may be of great benefit in these difficult reconstructions and is a valuable addition to the armamentarium of treatments for distorted glenoid anatomy. Eventually, the idea may become useful in treating other, less significant defects by re-creating more-normal biomechanics in SA without bone graft.

Am J Orthop. 2017;46(2):104-108. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.