Measurement of Capsular Thickness in Magnetic Resonance Arthrography in Idiopathic Adhesive Capsulitis of Hip

PURPOSE The clinical suspicion of idiopathic adhesive capsulitis of the hip (IACH) involves restricted range of motion and normal hip radiographs. The purpose of this study was to delineate the characteristic findings observed on magnetic resonance arthrography (MRA) by identifying the anatomical structures involved and their significance on clinical presentation of restricted range of motion. MATERIALS AND METHODS We retrospectively evaluated MRA's of 46 hips (44 patients) who suffered hip pain from September 2006 to August 2012 in our hospital. Of those, 10 cases (8 patients) with clinical suspicion of IACH were compared to 20 normal hip cases (control group). To identify anatomical evidence of adhesive capsulitis in the MRA's of the IACH group, capsular thickness was measured superiorly, inferiorly, anteriorly and posteriorly, and compared to that of the randomly selected control group. RESULTS Comparison of the MRA findings of the control group to that of the IACH group showed that there was a statistically significant increase in the mean thickness of the joint capsule superiorly and posteriorly (P<0.01), while comparison of examination findings revealed a statistically significant decrease in the mean range of motion (flexion 122.5°±5.5°/abduction 28.0°±2.8°/adduction 26.5°±2.4°/external rotation 30.5°±3.8°/internal rotation 25.5°±2.4°) in the IACH group. CONCLUSION A change in the capsular thickness on MRA is a common finding in IACH patients with the increase more evident in the posterior and superior capsules than the anterior and inferior capsules.