Pincer morphology is not associated with hip osteoarthritis unless hip pain is present

Abstract

ObjectiveTo assess the relationship between pincer morphology and radiographic hip osteoarthritis (RHOA) over 2‐,5‐,8‐ and 10‐years follow‐up, and to study the interaction between pincer morphology and pain.MethodsIndividuals from the prospective CHECK cohort were drawn. Anteroposterior pelvic and false profile radiographs were obtained. Hips free of definite RHOA (Kellgren and Lawrence (KL) 0 or 1) at baseline were included. Pincer morphology: lateral or anterior center edge angle, or both ≥40° at baseline. Incident RHOA: KL ≥2 or total hip replacement at follow‐up. Multivariable logistic regression with generalized estimating equations estimated the associations at follow‐up. Associations were expressed as unadjusted (OR) and adjusted odds ratios (aOR) with 95% confidence intervals (95% CI). An interaction term was added to investigate whether pincer morphology had a different effect on symptomatic hips.ResultsIncident RHOA developed in 69 hips (5%) at 2 years, 178 hips (14%) at 5 years, 279 hips (24%) at 8 years, and in 495 hips (42%) at 10 years follow‐up. No significant associations were found between pincer morphology and incident RHOA (aOR's 0.35 (95% CI 0.06‐2.15) ‐1.50 (95% CI 0.94‐2.38)). Significant interactions between pain and anterior pincer morphology in predicting incident RHOA were found at 5‐ 8‐ and 10 years follow‐up (ORs 1.97 (1.03‐3.78) ‐ 3.41 (1.35‐8.61)).ConclusionNo associations were found between radiographic pincer morphology and incident RHOA at any follow‐up moment. Anteriorly located pincer morphology with hip pain however was significantly associated with incident RHOA. This highlights the importance of studying symptoms and hip morphology simultaneously.