Shoulder Muscle Adiposity Can Predict the Efficacy of Corticosteroid Injections in Treating Adhesive Capsulitis After Rotator Cuff Repair Surgery.

Abstract

Shoulder stiffness is a common complication after rotator cuff repair (RCR) that may progress to adhesive capsulitis, impeding functional recovery. Although corticosteroid injections are frequently used, treatment response varies substantially across patients. This study investigated whether preoperative fatty infiltration into shoulder musculature predicts corticosteroid injection efficacy in managing post-RCR adhesive capsulitis. This retrospective cohort study included patients who developed adhesive capsulitis after primary RCR and subsequently received intra-articular corticosteroid injection between August 2013 and July 2022. Patients were stratified into effective and ineffective treatment groups by pain scores and range of motion at 8 weeks. Preoperative MRI assessed fatty infiltration using the Goutallier fatty degeneration index (GFDI). Receiver operating characteristic curve and binary logistic regression analyses identified key predictors. The noneffective group exhibited significantly higher mean rotator cuff GFDI values than the effective group (2.1±0.7 vs. 1.5±0.3; P<0.001). GFDI ≥1.875 was the only significant independent predictor of treatment failure (OR: 6.020; P=0.049). Preoperative fatty infiltration (GFDI ≥1.875) predicted six-fold increased risk of corticosteroid injection failure, helping clinicians identify high-risk patients for earlier alternative treatments.