Anterior capsular morphologic changes in osteonecrosis of the femoral head linked to impaired quality of life and range of motion

Pathoanatomical alterations in the anterior capsule of patients with osteonecrosis of the femoral head (ONFH) have not yet been identified. This study aimed to evaluate differences in the thickness and morphology of the anterior capsule and to explore further associations between them and quality of life. A total of 83 hips from 46 patients with ONFH were consecutively recruited, while 22 hips from 11 age- and sex-matched volunteers were collected as controls from January 2024 to September 2024. Participants were separated into 4 stages according to the Association Research Circulation Osseous classification. The thickness and morphology of the anterior capsule were assessed on the axial plane and coronal and axial planes by magnetic resonance imaging. Correlated analysis was subsequently performed between pathoanatomical alterations and quality of life scores, including the Short-Form-12-item Health Survey Version 2 (SF12) and the Oxford Hip Score (OHS), and range of motion (ROM). The anterior capsule thickness was significantly greater in stages III and IV patients than in stages I and II patients and controls (P < .001). Morphological alterations, including edema and delamination, were significant different at various stages (P < .001). The correlation between thickness and SF12, OHS, and ROM revealed moderate negative and morphological alterations showed similar outcomes. Patients with advanced-stage ONFH have thicker and more predominantly morphologically altered anterior capsules than patients in the initial stages. The thickness and morphological alterations both had a moderate negative correlation with SF12, OHS, and ROM.