Corticosteroid Dose and Efficacy in Shoulder Impingement Syndrome: A Systematic Review and Meta-Analysis.

To evaluate whether corticosteroid dose affects pain and functional outcomes in shoulder impingement syndrome (SIS) treated with subacromial injection. Systematic review and meta-analysis. Six databases (CINAHL, EMBASE, Ovid MEDLINE, Ovid HealthSTAR, PubMed, Web of Science) were searched from inception to July 2025. Outcomes were pooled using random-effects meta-analysis with meta-regression to assess association between dose and treatment effect. Twenty-three studies comprising 739 patients were included. Seven studies used triamcinolone-equivalent doses below 40 mg, while 16 used doses of 40 mg or more. The pooled improvement in pain was 3.00 points on the VAS (95% CI: 2.60-3.40). No significant association was found between corticosteroid dose and pain improvement (=0.003, P=0.814), with pooled VAS improvements of 2.85 (95% CI: 2.50-3.20) and 3.06 (95% CI: 2.54-3.58) for the low and high dose groups, respectively. For functional outcomes, the overall pooled SMD was 1.876 (95% CI: 1.370-2.383), with no dose-response relationship (=0.008, P=0.609). Subacromial corticosteroid injection produced clinically meaningful reductions in pain and improvement in function across the doses studied. These findings suggest a therapeutic ceiling effect, where lower doses may achieve comparable benefit; head-to-head trials are needed to confirm equivalence and establish optimal dosing guidelines.