Limited Preoperative Forward Flexion does not Impact Outcomes Between Anatomic or Reverse Shoulder Arthroplasty for Primary Glenohumeral Arthritis

Background Anatomic total shoulder arthroplasty (TSA) remains the treatment of choice for primary glenohumeral osteoarthritis with an intact rotator cuff (PGHOA). However, reverse total shoulder arthroplasty (RSA) has gained popularity as a primary procedure in select patients that may be at risk for postoperative rotator cuff dysfunction or glenoid loosening. The purpose of this study was to compare short-term outcomes between TSA and RSA in patients with PGHOA and limited preoperative forward flexion (FF). Methods A retrospective review was performed on a multi-institutional registry of patients to identify patients under the age of 80 undergoing TSA or RSA for PGHOA with preoperative FF ≤90°. Forty-five TSAs were identified and matched by age and sex to 45 patients undergoing RSA. A subset of 22 TSAs and 24 RSAs with severely limited preoperative FF of ≤70° was also analyzed. Range of motion including FF, external rotation (ER) and internal rotation (IR), strength, and patient reported outcomes (PROs) including visual analog scale (VAS) pain score, Western Ontario Osteoarthritis of the Shoulder (WOOS) index score, Veterans RAND 12 (VR-12) mental score, American Shoulder and Elbow Surgeons (ASES) score, and Constant-Murley Score were evaluated at a minimum of 2 years postoperative. Results No significant differences were observed in postoperative FF, ER, or strength measurements between groups. The limited FF TSA group achieved significantly improved IR compared to the RSA group (L2 vs. L4, p<0.002). No significant differences were observed between TSA and RSA in ASES, VAS, Constant or SANE scores (p > .05) for both the overall comparison and subset of patients with FF of ≤70°. However, patients in the RSA cohort showed a significantly higher return to normal sporting activities than the TSA group. Conclusions Patients under the age of 80 with PGHOA and limited preoperative FF achieve similar postoperative range of motion and PROs whether treated with TSA or RSA. Therefore, limited preoperative FF does not appear to be a major determinant of outcomes for PGHOA.