| Description: |
Background/Objectives: Classical reverse shoulder arthroplasty (RSA) with a high neck–shaft angle (NSA) of 155° has shown satisfactory outcomes. However, newer RSA designs aim to improve results by modifying the stem design. This study evaluates the 5-year outcomes of a stem design featuring a rectangular metadiaphyseal fixation and a 135° NSA. Methods: This prospective bicentric case series included and longitudinally followed up patients that were treated for cuff arthropathy, massive irreparable rotator cuff tears, or eccentric osteoarthritis using a non-cemented rectangular metadiaphyseal fixation stem with a 135° NSA (Univers Revers, Arthrex, Naples, FL, USA). Subjective and objective functional outcome scores (Constant–Murley Score (CS), Shoulder Pain and Disability Index (SPADI), and Subjective Shoulder Value (SSV)), range of motion (ROM), radiographic outcome, adverse events, complications, and quality of life were investigated. Results: This study enrolled 132 patients (59% female, mean age 75 years, SD 6). At the 5-year follow-up, subjective and objective outcomes significantly improved compared to baseline: CS (32.9 to 71.7, p < 0.001), SPADI (38.7 to 86.2, p < 0.001), and SSV (43.0 to 84.1, p < 0.001). ROM improved in flexion (80° to 142.4°, p < 0.001), abduction (71.5° to 130.2°, p < 0.001), internal rotation (p < 0.001), internal rotation at 90° abduction (12.7° to 45.0°, p < 0.001), and abduction strength (0.8 kg to 5.2 kg, p < 0.001). External rotation remained unchanged (32.1° to 32.0°, p = 0.125), but external rotation at 90° abduction improved (20.9° to 52.7°, p < 0.001). No signs of implant migration, subsidence, shift, tilt, alignment loss, or wear were observed, but scapular bone spur formation (11%), scapular notching grade 1 (10%), bone resorption (10%), and partial humeral radiolucent lines (1%) were reported. Conclusions: Rectangular stems with metadiaphyseal fixation and a 135° neck–shaft angle in RSA consistently improve shoulder function, showing no aseptic ... |