Correlations between MRI findings and outcome of capsular distension in adhesive capsulitis of the shoulder

[Purpose] The aim of this study was to investigate the association between magnetic resonance imaging (MRI) findings in patients with adhesive shoulder capsulitis and the therapeutic effect of capsular distension. [Subjects and Methods] We retrospectively reviewed the medical records of 57 patients who underwent capsular distension therapy after a diagnosis of adhesive capsulitis with clinical and MRI scans. Axillary joint capsular thickness by MRI was graded as I (≤3.6 mm), II (3.7-4.2 mm), and III (≥4.3 mm). Subcoracoid fat obliteration of the rotator interval was graded subjectively as absent, partial, and complete. [Results] Capsular thickness and fat replacement were correlated with passive range of motion (PROM) and pain score on a visual analog scale (VAS) by analysis of variance with a Bonferroni correction before treatment and by analysis of covariance with a Bonferroni correction after treatment. Visual analog scale (VAS) for patients with all grades decreased significantly after treatment and passive range of motion (PROM) for patients with all grades improved. No difference was detected between grades. [Conclusion] Although MRI is useful to evaluate adhesive capsulitis, MRI findings of shoulder did not predict the prognosis after capsular distension treatment.