Adhesive capsulitis (frozen shoulder) is a common cause of shoulder pain and disability. Previous studies have reported that intra-articular corticosteroid injections are of benefit compared with placebo up to 6 weeks. It has been suggested that the structures primarily involved in adhesive capsulitis are the capsule and the rotator interval. Systematic reviews have concluded that there is limited evidence of the treatment effectiveness of intra-articular corticosteroid injections and that high-quality primary research is required. The aim of this study was to compare ultrasound-guided intra-articular corticosteroid injection and combined intra-articular and rotator interval injection in a double-blind, sham-controlled randomized clinical trial. The main outcome measure was the group difference in change in shoulder pain (0-10) at 6 weeks. One hundred twenty-two patients were randomized (42 to intra-articular injection, 40 to combined intra-articular/interval injection, and 40 to sham injection). For both corticosteroid injection groups, there was a significant difference compared with sham injection at week 6. The mean group difference (adjusted for gender, age, dominant arm, and duration) in change in shoulder pain for the intra-articular vs sham injection was -1.7 (95% confidence interval, -2.7 to -0.6, P = 0.002) and -2.1 (95% confidence interval, -3.2 to -1.1, P = 0.0001) for the combined injection vs sham injection. The significant group differences were maintained at week 12 but not at week 26. Similar results were found for the secondary outcome measures (night pain, Shoulder Pain and Disability Index). Differences between the corticosteroid groups were not significant at any time.
Trial registration: ClinicalTrials.gov NCT00840229.