Thirty two patients with full-thickness posterosuperior rotator cuff tears were randomized to immobilization with an abduction neutral-rotation brace (n=16 analyzed) or a conventional arm sling (n=16). The primary outcomes were passive shoulder ROM (forward flexion, external rotation, internal rotation) measured serially; secondary outcomes were pain (VAS) and Constant–Murley Score (CMS). Outcomes were assessed preoperatively and at 6 weeks, 3, 6, and 12 months. Overall, the results revealed better early ROM (e.g., forward flexion and external rotation at 3 months) and lower pain at 6 weeks with the brace, while 12-month ROM converged and CMS was only modestly higher in the brace group at 12 months. These findings suggest abduction-neutral immobilization facilitates earlier recovery without added complications.