Changes in hip joint anatomical shape as a predictor of osteoarthritis

Hip osteoarthritis (HOA) is one of the leading causes of musculoskeletal disability worldwide, yet its etiology remains incompletely understood. Its pathogenesis is multifactorial, involving systemic factors and biomechanical alterations of the hip joint that trigger degenerative changes.

The aim of this study was to identify the most informative radiographic views and the key acetabular and proximal femoral parameters for detecting structural abnormalities of the hip joint that may contribute to the development of HOA.

This observational case-control study included 156 patients older than 55 years who underwent total hip arthroplasty for HOA (osteoarthritis (OA) group) and 61 age-matched controls without clinical HOA, recruited from a single center between 2019 and 2022. Patient demographics, clinical history, and hip-specific functional scores were collected. Standardized anteroposterior (AP), frog-leg lateral (LL), and Dunn 45° radiographs were obtained, and multiple radiographic parameters were measured.

Asymptomatic contralateral hips in patients with OA had significantly more cam-type deformities (higher alpha angles, lower head-neck offset ratios, and a higher prevalence of pistol-grip deformity) than those in the control group (p < 0.001). In contrast, pincer-type features were more common in the control group. Logistic regression analysis identified higher alpha angles, greater femoral neck diameter, and lower head-neck offset ratios as predictors of OA, whereas a larger femoral head diameter was identified as a protective factor (model area under the curve (AUC) = 0.90). Bone quality was superior in the control group, with longer femoral neck axis lengths and higher Singh indices (p < 0.001).

Radiographic markers of cam-type femoroacetabular impingement (FAI) are significantly more prevalent in patients with HOA and may serve as early indicators of disease risk. Dunn and LL views are optimal for detecting these abnormalities. A larger femoral head diameter, as measured on both AP and LL radiographic views, appears to be a protective factor against the development of HOA. Understanding these morphological differences may facilitate earlier diagnosis and support preventive strategies for HOA.