Eighty two patients with small–medium full-thickness supraspinatus tears and concomitant shoulder stiffness were randomized to arthroscopic rotator cuff repair (ARCR) with capsular release (n=41) or ARCR without capsular release plus a single intra-articular triamcinolone (40 mg in 1 mL) injection at 2 months post-op (n=41). The primary outcome was American Shoulder and Elbow Surgeons (ASES). Secondary outcomes included VAS pain, Constant score, Korean Shoulder Scale, ROM (forward flexion, external rotations, internal rotation), and structural integrity (MRI at 12 months). Outcomes were assessed pre-op; at 3, 6, and 12 months; and at last follow-up (mean 26.5 months). Overall, the results revealed significantly improved pain, function, and ROM from baseline in both groups, with no between-group differences at any time point except lower 3-month pain in the injection group. Retear rates were similar between groups. These findings suggest a single 2-month postoperative corticosteroid injection can substitute for intra-operative capsular release in this population.