Acetabular morphometry for determining hip dysplasia in the Singaporean population.

PURPOSE To assess and evaluate the usefulness of 7 morphological measurements of the acetabulum in establishing the prevalence of acetabular dysplasia in the Singaporean population. METHODS Standardised plain anteroposterior radiographs of 522 hip joints of 261 asymptomatic patients (mean age, 60 years; range, 16-99 years) were evaluated. The 7 morphological measurements were centre-edge angle, acetabular angle, depth-to-width ratio, roof obliquity, extrusion index, lateral subluxation, and peak-to-edge distance. RESULTS 19 (7.3%) patients were acetabular dysplastic (centre-edge angle of <20 degrees). The mean centre-edge angle was 31.2 degrees (range, 5-52 degrees), acetabular angle 39.46 degrees (range, 10-58 degrees), depth-to-width ratio 0.32, roof obliquity 7.86 degrees, extrusion index 0.18, lateral subluxation 9.9 mm, and the peak-to-edge distance 15.65 mm. CONCLUSION Centre-edge angle was the most useful measurement and correlated significantly with acetabular angle, extrusion index, peak-to-edge distance, and roof obliquity. These preliminary results show a relatively higher rate (7.3%) of acetabular dysplasia in the Singaporean population, compared with other similar but larger Asian studies performed in Hong Kong (1.1%) and Korea (1.8%).