Computed Tomography Arthrography Findings of Idiopathic Adhesive Capsulitis of the Hip: An Analog of Adhesive Capsulitis of the Shoulder

OBJECTIVE: To identify useful imaging findings for the diagnosis of idiopathic adhesive capsulitis of the hip (ACH) on computed tomography arthrography (CTA). MATERIALS AND METHODS: Twenty-eight consecutive patients (29 hips; 7 males; mean age, 45.7 years; age range, 17–67 years) with ACH from October 2009 to March 2017 and 29 age- and sex-matched control patients from 2014 to 2016 were enrolled. All CTA images were evaluated by 2 radiologists independently for joint distensibility (anterior-posterior [AP] and superior-inferior [SI] joint cavity filling ratios), the presence of contrast filling around the ligamentum teres, and extracapsular contrast leakage. Fisher's exact test, Mann-Whitney U test, analysis of variance, and receiver operating characteristic curves were used for statistical analysis. P value less than 0.05 was considered to indicate statistical significance. RESULTS: The anterior joint cavity was significantly more obliterated in the ACH group (mean size, 3.7–4.0 mm) than in the control group (mean size, 4.8–5.0 mm; p < 0.05). The AP filling ratio was also significantly lower in the ACH group (0.6 vs. 1.1; p < 0.05) and decreased more as the ACH stage increased (mean anterior joint cavity size: 1.15 mm in stage 3 vs. 4.68 mm in stage 1; p < 0.05). Extracapsular contrast leakage was more common in the ACH group (27–28 vs. 20–21; p = 0.041 and 0.025, respectively). CONCLUSION: On CTA, the anterior joint cavity may have earlier and more marked obliteration than joint cavities on other sides, and may be accompanied by extracapsular contrast leakage in ACH. These CTA findings may be helpful in the diagnosis of ACH.