126 patients with idiopathic adhesive capsulitis were randomized to site of corticosteroid injection: subacromial, intra-articular, or combined subacromial and intra-articular injection. The purpose of this study was to determine if subacromial (SA) corticosteroid injections were noninferior to intra-articular (IA) injections and if there was an additive effect of combined SA and IA injections. The outcome measures evaluated were pain (visual analog scale) and shoulder function (American Shoulder and Elbow Surgeon score, subjective shoulder value and the range of motion). The results of this trial indicated that SA injection was inferior to the IA and IA+SA combined injections over the 12-week follow-up period and that there may be an additive benefit of a combined injection for internal rotation.