Sonography in diagnosis of adhesive capsulitis of the shoulder: a case-control study.

Abstract

Adhesive capsulitis (AC) of the shoulder has been a diagnosis of exclusion on sonography due to lack of specific diagnostic criteria. This study prospectively assesses the efficacy of sonography using multiple static and dynamic parameters for diagnosis of AC. Shoulder sonography was performed independently by two musculoskeletal radiologists on 90 subjects (60 symptomatic and 30 controls). All symptomatic subjects were subjected to an MRI. Based on clinical and MRI diagnosis, three groups were made: AC (n=30), painful shoulders (PS) (n=30), and control group (CL) (n=30). The sonographic parameters studied were: coracohumeral ligament (CHL) thickness, increased soft tissue in rotator interval (static parameters) and restriction of abduction and external rotation on dynamic scanning. These were compared within the three groups and the accuracy of each parameter in isolation and in combination for diagnosis of AC was calculated. Sonographic visualisation of CHL (96.7%) and its mean thickness (1.2mm) were highest in the AC group (p<0.01). A cut-off value of 0.7mm was found to be accurate (sensitivity 93.1%, specificity 94.4%) for diagnosing AC. Increased soft tissue in the rotator interval was seen in the AC group and had a high sensitivity of 86.2% and specificity of 92.8%. On dynamic scanning, restriction of external rotation was specific (sensitivity 86.2%, specificity 92.8%), whereas restriction in abduction was non-specific (specificity 6.7%). Inter-observer agreement was substantial for CHL visualisation (kappa 0.66). Overall, sonography, using multiple parameters, revealed a high sensitivity and specificity (100 and 87%, respectively) for diagnosis of AC of the shoulder. Sonography revealed a high accuracy for diagnosing AC of the shoulder and in differentiating it from other causes of painful shoulder. It, thus, has the potential to be adopted as a preferred imaging modality.