Comparison of Clinical Outcome and Return to Work Following Exactech Equinoxe Reverse Total Shoulder Arthroplasty: Pectoralis Major Tendon Transfer versus Subscapularis Repair.

Abstract

Reverse total shoulder arthroplasty (rTSA) has become a widely accepted treatment for rotator cuff tear arthropathy. Recent studies have highlighted the importance of the subscapularis (SSC) tendon in maintaining postoperative stability and optimizing functional outcomes after rTSA. When SSC repair is not feasible or is associated with a high risk of failure, pectoralis major (PM) tendon transfer has been proposed as an alternative strategy to restore internal rotation (IR) function and stability. However, no comparative studies have directly evaluated whether PM tendon transfer provides clinical outcomes and return to work (RTW) results comparable to those achieved after SSC repair. This retrospective comparative study reviewed consecutive patients who underwent rTSA from January 2022 to May 2023. Patients were divided into two groups based on the SSC management strategy: the SSC repair group (group R) and the PM tendon transfer group (group P). The primary outcomes were the Activities of Daily Living involving Internal Rotation (ADLIR) score and rate of RTW. Secondary clinical outcomes were assessed by other patient-reported outcome measurements, active range of motion (aROM), and aROM strength. The status of repaired SSC and transferred PM were evaluated as a radiologic outcome. Factors associated with RTW were identified through univariable analysis. 69 patients were included in the study population with 42 classified into group R and 27 to group P. Both groups showed significant postoperative improvements in clinical outcomes. The ADLIR score, defined as the primary outcome, was significantly higher in Group P than in Group R (24.9±4.5 vs 28.1±3.0, p=0.006). Moreover, postoperative IR at back (5.6±1.7 vs 6.5±0.9, p=0.010) and IR Strength (21.4±5.3 vs 29.4±2.8, p<0.001) of group P were significantly higher than that of group R. In radiologic outcome, SSC retears were identified in 13 of 42 patients (31.0%), whereas no PM tendon retears were observed in group P. The rate of RTW defined as the co-primary outcome showed no significant difference between two groups (p=0.063). However, the rate of RTW at the heavy level work was significantly higher in the Group P (p=0.049). Multivariable analysis demonstrated that PM tendon transfer was independently associated with a higher likelihood of return to work than SSC repair (adjusted OR, 5.73; 95% CI, 1.07-30.85; P = 0.042). These findings suggest that PM tendon transfer is a reasonable treatment option for patients with irreparable subscapularis tears when anatomical SSC repair is not feasible or durable healing is unlikely, rather than evidence that PM transfer is superior to SSC repair. Level III, Retrospective Cohort Comparison, Treatment Study.