Hip dysplasia as risk factor for clinically relevant and radiographic hip osteoarthritis: 10-year results from the CHECK cohort

To investigate hip dysplasia as a risk factor for clinically relevant and incident radiographic hip osteoarthritis.From a prospective cohort (CHECK) of 1002 middle-aged, new consulters for hip and/or knee pain, 468 hips (251 individuals) were selected based on hip pain, available lateral center edge angle (LCEA) and absence of definite radiographic hip OA (Kellgren and Lawrence grade (KL) <2) at baseline, as well as available follow-up measures. Clinically relevant hip OA was defined by an expert diagnosis based on clinical and radiographic data obtained between year 5-10 from baseline. Incident radiographic hip OA was defined by KL grade ≥2 or a total hip replacement at the 10-year follow-up. Associations between hip dysplasia (LCEA ≤20°) and outcomes were expressed in odds ratios (OR) adjusted for age, sex and BMI.At baseline, participants had a mean age of 55.5 years (SD 5.4), 88% were female and, on hip level, the prevalence of hip dysplasia was 3.6% (n = 17). After 10 years, hip dysplasia was associated with an increased risk for clinically relevant hip OA (OR 2.80 (95% CI 1.15, 6.79), but not for incident radiographic hip OA (OR 0.78 (95% CI 0.26, 2.30)).In the long term, baseline hip dysplasia was associated with an increased risk for clinically relevant hip OA, but not for incident radiographic hip OA. With this in mind, we suggest that future research investigating the link between hip dysplasia and OA strive to include a definition for OA that is clinically relevant.