Fifty one patients with impingement syndrome and mild stiffness were randomized to receive either a glenohumeral (GH; n=25) or subacromial (SA; n=26) steroid injection of 40 mg of triamcinolone. The outcomes of interest were the improvement in range of motion (ROM) in forward elevation, external rotation, and internal rotation, and clinical scores including pain visual analog scale (pVAS), American Shoulder and Elbow Surgeons (ASES) score, and the Constant-Murley score, measured at specific intervals before and after 3, 7, and 13 weeks following the injection. Overall, the results of the study revealed that both GH and SA injections significantly improved ROM and clinical scores after 13 weeks, with GH injections leading to an earlier gain in ROM and certain clinical scores within the first 7 weeks.