Increased Inferior Capsular Thickness on Magnetic Resonance Imaging Is Associated With Adhesive Capsulitis of the Hip.

Purpose: To investigate magnetic resonance imaging (MRI) findings associated with adhesive capsulitis of the hip and identify differences in capsular thickness between patients with the diagnosis and controls matched by age, sex, and body mass index (BMI). Methods: Consecutive patients with the diagnosis of adhesive capsulitis of the hip were identified and included for retrospective chart review and compared with an equal number of age, sex, and BMI-matched controls. Patients were excluded if they had prior hip surgery or did not have an MRI or magnetic resonance arthrography (MRA) obtained at our institution to allow for calibrated measurement. Quantitative data were collected on capsular thickness in 4 locations (anterior, posterior, superior, inferior) and MRA filling ratios. Nonquantitative data were collected regarding the presence or absence of labral tears. Results: Fourteen patients were included along with 14 controls. Patients with adhesive capsulitis have significantly thicker inferior capsules compared with controls (3.43 vs 2.50 mm; Conclusions: Adhesive capsulitis of the hip is associated with thicker inferior joint capsules compared to age, sex, and BMI-matched controls. No differences were found in the thickness of anterior, posterior, or superior joint capsules. Level of Evidence: Level III, retrospective diagnostic case-control.