Pharmacological interventions for early-stage frozen shoulder: a systematic review and network meta-analysis

Objectives: To evaluate the efficacy of pharmacological interventions for treating early-stage, pain predominant, adhesive capsulitis, also known as frozen shoulder. Methods: We performed a systematic review in accordance with Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Searches were conducted on MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials on 24 February 2022. Outcomes were shoulder pain, shoulder function and range of movement. Synthesis involved both qualitative analysis for all studies and pairwise meta-analyses followed by a network meta-analysis for randomized controlled trials (RCTs). Results: A total of 3252 articles were found, of which 31 met inclusion criteria, and 22 of these were RCTs. IA injection of CS (8 RCTs, 340 participants) and IA injection of platelet-rich plasma (PRP) (3 RCTs, 177 participants) showed benefit at 12 weeks compared with physical therapy in terms of shoulder pain and function, while oral NSAIDs (2 RCTs, 44 participants) and IA injection of hyaluronate (2 RCTs, 42 participants) did not show a benefit. Only IA PRP showed benefit over physical therapy for shoulder range of movement. Conclusion: These results shows that IA CS and IA PRP injections are beneficial for early-stage frozen shoulder. These findings should be appraised with care considering the risk of bias, heterogeneity and inconsistency of the included studies. We believe that research focused on early interventions for frozen shoulder could improve patient outcomes and lead to cost-savings derived from avoiding long-term disability. Further well-designed studies comparing with standardized physical therapy or placebo are required to improve evidence to guide management.