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

Abstract Background Adhesive capsulitis (AC) 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 AC. Design This retrospective study enrolled AC patients aged >35 years who received intra-articular corticosteroid injections. The response was determined based on patients' pain and range-of-motion (ROM) three months after the injection. Demographic data, medical comorbidities, and radiographic parameters (critical shoulder angle [CSA] and acromial index [AI]) were compared between the effective and noneffective groups. Receiver operating-characteristic (ROC) curves and logistic regression were used to identify the predictors of injection effectiveness. Results This study included 325 patients with primary AC, who were divided into responder (189 patients, 58.2%) and non-responder (136 patients, 41.8%) groups. The ROC curve revealed that the AI score indicated favorable discrimination for predicting a poor response to injections, whereas the CSA score did not. Logistic regression revealed that the pain period, diabetes mellitus, and AI are predictors of non-responders to injections. Conclusion Long pain duration, the presence of diabetes mellitus, and an AI score of >0.711 were predictors of non-response to corticosteroid injections for primary AC patients.