Anterior capsular abnormality: another important MRI finding for the diagnosis of adhesive capsulitis of the shoulder

Objective To evaluate the usefulness of anterior capsular abnormality, thickening, and abnormal signal intensity on MRI for the diagnosis of adhesive capsulitis of the shoulder. Materials and methods This retrospective study included 29 patients with adhesive capsulitis and 20 controls. Clinical criteria with significant restricted passive motion was used for the diagnosis of adhesive capsulitis. The anterior capsular thickness and signal intensity were evaluated on the thickest portion of anterior glenohumeral joint capsule, located deep to the subscapularis muscle. In addition, the previously known MR findings of adhesive capsulitis, such as humeral and glenoid capsular thickness in axillary recess, maximal axillary capsular thickness, and coracohumeral ligament thickness, were measured. The presence of humeral and glenoid capsular abnormal hyperintensity in axillary recess, abnormal hyperintensity, and obliteration of the subcoracoid fat triangle were also evaluated. Results All MRI findings significantly differed between adhesive capsulitis and controls. Among MR findings, multivariable analysis showed that anterior capsular thickness, maximal axillary capsular thickness, and anterior capsular abnormal hyperintensity were variables that could differentiate adhesive capsulitis from the control group, with odds ratios of 7.97, 17.75, and 12.41, respectively (p < 0.05). In ROC analysis, the anterior capsular thickness showed high diagnostic performances with an AUC of 0.897. The cut-off value of anterior capsular thickness at 3.5 mm showed excellent diagnostic accuracy, with sensitivity of 68.97% and specificity of 100%. Conclusions Anterior capsular abnormality, thickening, and abnormal hyperintensity can be used for the diagnosis of adhesive capsulitis of shoulder, in addition to previously known abnormal MRI findings.