Acetabular dysplasia predicts incident osteoarthritis of the hip: the Rotterdam study

To investigate the association between acetabular dysplasia and the incidence of radiographic osteoarthritis (OA) of the hip in a population-based sample of elderly subjects.

Radiographs of the hip at baseline and at followup (mean followup time 6.6 years) were evaluated in 835 men and women (age >or=55 years) from the Rotterdam Study. Subjects with a baseline Kellgren/Lawrence grade of 0 or 1 in both hips were included in the study. Incident radiographic OA of the hip was defined as a decrease of joint space width of the hip (>or=1.0 mm) at followup. Acetabular dysplasia was assessed using the center-edge angle and the acetabular depth. The association between acetabular dysplasia and incident radiographic hip OA was assessed by calculating odds ratios using multivariate regression analysis.

In this study population with a mean +/- SD age of 65.6 +/- 6.5 years, 9.3% developed incident radiographic hip OA. Subjects with acetabular dysplasia (center-edge angle <25 degrees ) had a 4.3-fold increased risk for incident radiographic OA of the hip (95% confidence interval 2.2-8.7) compared with subjects without acetabular dysplasia. These associations were independent of known determinants of hip OA such as age, sex, and body mass index (BMI), but tended to be enhanced by female sex, heavy mechanical load, and low BMI.

In a study population age >or=55 years, acetabular dysplasia is still a strong independent determinant of incident radiographic hip OA.