In 2003, the first reverse shoulder prosthesis was approved in the United States. Prior to its approval, shoulder arthroplasty surgeons in the United States utilized hemiarthroplasty, resurfacing, and anatomic total shoulder arthroplasty (ATSA) for various etiologies. The classic indication for ATSA has been osteoarthritis. However, degenerative conditions with a deficient rotator cuff were typically treated with hemiarthroplasty because of the increased concern that abnormal glenohumeral motion and eccentric glenoid loading would result in subsequent component loosening.¹ Initially, the reverse shoulder prosthesis was approved for cuff tear arthropathy (CTA) in elderly, low-demand patients.¹,²,³ Since 2003, the use of shoulder arthroplasty, and in particular, reverse total shoulder arthroplasty (RTSA), has expanded considerably.¹,²,³ The initial narrow indications for RTSA were expanded based upon the initial successful results, evolving technology, and an increasing level of comfort with the procedure such that, currently, the majority of shoulder arthroplasties performed are of the reverse design.¹,²,³ The expanded indications for RTSA include massive irreparable rotator cuff tear without arthritis, rheumatoid and other inflammatory glenohumeral arthritis, tumor, acute fractures, posttraumatic arthritis, osteoarthritis with significant bone loss or deformity, and chronic glenohumeral dislocation.¹,²,³ In this chapter we will focus on clinical situations in which both ATSA and RTSA are treatment options and the factors to consider when determining the preferred approach.

Osteoarthritis is the most common indication for an ATSA.⁴,⁵ In the United States, one-third of the population have osteoarthritis, and the glenohumeral joint is the third most common joint to be replaced.⁵,⁶ Outcome studies consistently report good and excellent outcomes following ATSA, and it is considered a successful treatment for end-stage glenohumeral arthritis.⁵,⁶,⁷,⁸,⁹,¹⁰,¹¹,¹² The average age for a patient undergoing ATSA has decreased over the past decade and has been reported to be as low as 64 years.¹,⁶ ATSA decreases pain, improves range of motion and function, and achieves high rates of patient satisfaction.⁴,⁵,⁶,⁷,¹⁰,¹² For patients with glenohumeral osteoarthritis and an intact rotator cuff, it is evident that ATSA is the preferred treatment (FIGURE 7.1).

The importance of an intact rotator cuff for a successful ATSA cannot be overemphasized, and identifying patients with rotator cuff tears or dysfunction is important in deciding whether ATSA is the best option. Of note, up to 10% of patients undergoing ATSA have rotator cuff tears.⁵,⁷,⁹ If a patient has rotator cuff pathology, the supraspinatus tendon is typically involved with half of the tears partial thickness and half of the tears full thickness.⁷,⁸,⁹ Simone et al reported on 33 ATSAs with simultaneous rotator cuff repair with an average follow-up of 5 years. Of the 33 shoulder replacements, 10 had small tears, 14 had medium tears, 9 had large tears, and none had massive tears.⁹ While all patients reported improved pain, function, and satisfaction, those patients with small tears had greater improvement of forward elevation.⁹ Six of the medium- and large-sized tears exhibited postoperative instability indicating that the rotator cuff repair did not heal.⁹ Postoperative instability was not identified in the small tear group.⁹ Therefore, smaller, isolated tears of the supraspinatus should not be considered a contraindication for ATSA.⁷,⁹ However, in older patients with larger rotator cuff tears, RTSA would be the preferred option.⁹ Livesey et al also retrospectively reviewed patients who underwent ATSA with concurrent rotator cuff repair. These authors reported on 45 procedures with a minimum follow-up of 2 years.⁸ From this cohort, 31% had a poor result, while 18% required another operation.⁸ This study provided further support for the use of RTSA in patients with glenohumeral arthritis and a larger concurrent rotator cuff tear even if the tear is repairable.

As shoulder arthroplasty surgeons have become increasingly confident about the outcomes of RTSA, there has been a trend toward considering RTSA as the preferred option in patients with osteoarthritis and an intact
rotator cuff based primarily on increasing age. There is a general agreement that an ATSA requires an intact and functioning rotator cuff for a successful outcome. There is also a general agreement that as patients age, there is concurrent rotator cuff degeneration. There are situations in which a “structurally” intact rotator cuff may not be “functionally” intact, particularly after the manipulation that occurs during a shoulder arthroplasty. We have certainly encountered patients with ATSA, who at the time of surgery clearly had a structurally intact rotator cuff. However, postoperatively, these patients are unable to regain active range of motion and present with the clinical appearance of rotator cuff deficiency. This generally occurs in older patients in their 70s and 80s, and this situation has led to the question of whether RTSA is preferred for patients with osteoarthritis with an intact rotator cuff based solely on advancing age (FIGURE 7.2).

Currently, there is no age-specific indication for RTSA in patients with glenohumeral arthritis and an intact rotator cuff. However, there is some literature that provides important information. Wright et al specifically compared ATSA and RTSA for the treatment of glenohumeral osteoarthritis with an intact cuff. In this series of 135 patients, all patients were older than 70 years and had preoperative active forward elevation of less than 90° despite imaging showing an intact cuff.¹³ Of the 135 patients, 33 underwent RTSA and 102 underwent ATSA.¹³ They found no differences in complication rates, revision rates, patient-reported outcomes, patient satisfaction, and pain scores.¹³ Both groups reported a high level of satisfaction with a final range of motion that allowed performance of overhead activities.¹³ The authors recommended an expanded role for RTSA in older patients with glenohumeral arthritis and an intact rotator cuff.¹³ Furthermore, Brewley et al reported a retrospective cohort study of 1250 shoulder replacements, which included 518 ATSAs and 732 RTSAs.¹⁴ With an average follow-up of 50 months, all shoulder replacements improved pain, function, and range of motion.¹⁴ However, patients younger than 65 years with ATSAs and those younger than 60 years with RTSAs were noted to have higher revision rates.¹⁴ ATSA had a three times higher and RTSA had a five times higher revision rate.¹⁴ This study adds support that there may be an age indication for specific shoulder arthroplasty procedures.

To gain a more global perspective on the impact of age and the use of RTSA in patients with osteoarthritis and an intact rotator cuff, a multicenter international database was analyzed (Exactech, Gainesville, Florida). Specifically, this database included 2940 shoulder replacements performed between 2007 and 2018 in patients with glenohumeral arthritis and an intact rotator cuff (TABLE 7.1). For ATSA, the mean age of the first 200 patients was 67.5 years; the mean age for the last 200 ATSA patients decreased to 65.5 years. For RTSA, the mean age of the first 200 patients was 74.6 years; the mean age for the last 200 RTSA patients decreased to 72.6 years. These data indicate that for patients with glenohumeral osteoarthritis and an intact rotator cuff, as experience with RTSA has increased, there is a trend toward reserving ATSA for younger patients and also performing RTSA in younger patients. Using this same database, patients undergoing ATSA and RTSA were subdivided based upon age. ATSA was more commonly performed in all age groups up to age 76 to 79 years, at which point the trend changed to RTSA. Based upon this database, in patients with glenohumeral osteoarthritis with an intact rotator cuff, RTSA is now being performed at a younger age and has become the preferred procedure in patients in the 76-to 79-year age group. Although there is no definitive age-specific indication currently, it is certainly an option in this patient population based upon surgeon assessment and preference.

Approximately 4% of complete rotator cuff tears progress to CTA, which is characterized by superior migration of the humeral head leading to progressive degenerative changes of the glenoid, acromion, and humeral head.¹⁵,¹⁶,¹⁷ The superior migration of the humeral head is caused by an unopposed pull of the deltoid due to an unbalanced force couple.¹⁶ CTA is more common in elderly women and may present with the classically described “pseudoparalysis.”¹⁵,¹⁶ Prior to RTSA, hemiarthroplasty was utilized for CTA.¹⁷ The initial indication for RTSA in the United States was CTA, and it is now the preferred treatment of choice.¹⁵,¹⁶,¹⁷,¹⁸,¹⁹,²⁰,²¹ The reverse prosthesis design creates a more distal and medial center of rotation, which allows the deltoid to restore arm elevation and abduction.¹⁷,¹⁸,²⁰ The outcomes of RTSA for CTA have been consistently successful and much improved compared with earlier results using hemiarthroplasty.¹⁶,¹⁷,¹⁹,²⁰,²¹
These results with RTSA are sustained over long-term follow-up as Gerber et al recently reported. For 22 CTA patients treated with RTSA and a minimum 15 year follow-up, forward elevation improved from 53° to 101° and abduction improved from 55° to 86°.¹⁹ Furthermore, RTSA for CTA has been noted to have greater improvement compared to RTSA performed for other glenohumeral pathologies.¹⁶,¹⁷,²⁰ For CTA, RTSA is clearly the preferred arthroplasty option (FIGURE 7.3).

Rotator cuff tears are commonly diagnosed with increasing patient age and often occur in the absence of glenohumeral arthritis.²² Treatment options for patients with irreparable rotator cuff tears without arthritis have included débridement with or without subacromial decompression, tuberoplasty, biceps tenotomy or tenodesis, partial rotator cuff repair, and superior capsular reconstruction with varying levels of success.²²,²³,²⁴,²⁵,²⁶ Based upon the success of RTSA in patients with rotator cuff deficiency and glenohumeral arthritis, the indications for RTSA have been expanded to include massive, irreparable rotator cuff tears in the absence of arthritis. In this patient population, RTSA has proven to be very successful with implant survival greater than 90% at 10 years²²,²⁴,²⁵,²⁶ (FIGURE 7.4).