Rotator Interval vs Posterior Approach Ultrasound-guided Corticosteroid Injections in Primary Frozen Shoulder: A Meta-analysis of Randomized Controlled Trials

Objective To compare the efficacy of rotator interval (RI) vs posterior approach (PA) ultrasound (US) guided corticosteroid injections into the glenohumeral (GH) joint in primary frozen shoulder (PFS). Data Sources A systematic literature search for all relevant studies on Medline, Scopus, Embase, Web of Science, and Cochrane Central, up to January 2023 was conducted. Study Selection Randomized controlled trials that directly compared the US-guided corticosteroid injection into the RI and GH joint using PA in patients clinically and radiographically diagnosed with PFS. Data Extraction The primary outcome was pain, and the secondary outcomes were function, and range of motion (ROM). Two authors independently assessed the risk of bias using the Cochrane risk-of-bias tool version 2. A random-effects model and generic inverse variance method were performed. Effect sizes were estimated using mean difference (MD) and standardized mean difference (SMD). Data Synthesis A total of 5 clinical trials involving 323 subjects were included for the meta-analysis. US-guided corticosteroid injections into the RI revealed significant pain relief (MD 1.33 [95% confidence interval (CI) 0.20 to 2.46]; P=.02) and significant functional improvement (SMD 1.31 [95% CI 0.11 to 2.51]; P=.03) compared with the PA after 12 weeks. Conclusion The results suggest the injection of corticosteroid into RI space is more effective than PA after 12 weeks in improving both pain and functional scores in patients with PFS.