What is the most predictive magnetic resonance imaging finding of rotator cuff tear concomitant with shoulder stiffness?

BACKGROUND: Common magnetic resonance imaging (MRI) findings in adhesive capsulitis are not often evident in rotator cuff tear concomitant with shoulder stiffness. This study aimed to determine the most predictive MRI finding of rotator cuff tear with shoulder stiffness to differentiate from that without stiffness. MATERIALS AND METHODS: The data of patients who underwent arthroscopic rotator cuff repair between January 2014 and October 2019 were retrospectively reviewed. Stiffness was defined as forward flexion <120°, external rotation at side <30°, and internal rotation at back <L3 in the active range of motion. Propensity score matching (1-to-1) was performed between the stiff and control groups by sex, age, and tear size, and 76 patients per group were matched. Anterior capsular thickness, maximal humeral/glenoid capsular thickness in the axillary recess, coracohumeral ligament thickness, the presence of hyperintensity in the anterior capsule and humeral/glenoid capsule in the axillary recess, and hyperintensity and obliteration of the subcoracoid fat triangle were evaluated. RESULTS: Anterior capsular thickness, glenoid capsular thickness in the axillary recess, and anterior and axillary capsular hyperintensities were significantly more dominant in the stiff group (all P < .05) than in the control group. Anterior capsular thickness and anterior capsular abnormal hyperintensity could be used to differentiate between the stiff and control groups (P < .05). Anterior capsular thickness showed high diagnostic performance with an area under the receiver operating characteristic curve of 0.993. The cut-off value for stiffness was 3.07 mm (sensitivity, 96.1%; specificity, 100%). CONCLUSION: Anterior capsular thickening and abnormal hyperintensity were the most predictive MRI findings for stiffness in patients with rotator cuff tear and stiffness to differentiate from patients with rotator cuff tear without stiffness.