Predictive Factors of Intra-articular Corticosteroid Injections With Ultrasound-Guided Posterior Capsule Approach for Patients With Primary Adhesive Capsulitis

Background: Adhesive capsulitis affects the shoulder joint, causing pain and limiting motion. In clinical practice, the effectiveness of injections varies, and the factors influencing their success remain unclear. This study investigates the predictors of effective corticosteroid injections in patients with primary adhesive capsulitis. Design: This retrospective study enrolled adhesive capsulitis patients older than 35 yrs who received intra-articular corticosteroid injections. The response was determined based on patients’ pain and range of motion 3 mos after the injection. Demographic data, medical comorbidities, and radiographic parameters (critical shoulder angle and acromial index) were compared between the effective and noneffective groups. Receiver operating characteristic curves and logistic regression were used to identify the predictors of injection effectiveness. Results: This study included 325 patients with primary adhesive capsulitis, who were divided into responder (189 patients, 58.2%) and nonresponder (136 patients, 41.8%) groups. The receiver operating characteristic curve revealed that the acromial index score indicated favorable discrimination for predicting a poor response to injections, whereas the critical shoulder angle score did not. Logistic regression revealed that the pain period, diabetes mellitus, and acromial index are predictors of nonresponders to injections. Conclusions: Long pain duration, the presence of diabetes mellitus, and an acromial index score greater than 0.711 were predictors of nonresponse to corticosteroid injections for primary adhesive capsulitis patients.