Our study evaluated the reliability of the Crowe and Hartofilakidis classification systems for developmental dysplasia of the hip in adults. The anteroposterior radiographs of the pelvis of 145 patients with 209 osteoarthritic hips were examined twice by three experienced hip surgeons from three European countries and the abnormal hips were rated using both classifications. The inter- and intra-observer agreement was calculated.

Interobserver reliability was evaluated using weighted and unweighted kappa coefficients and for the Crowe classification, among the three pairs there was a minimum kappa coefficient with linear weighting of 0.90 for observers A and C and a maximum kappa coefficient of 0.92 for observers B and C. For the Hartofilakidis classification, the minimum kappa value was 0.85 for observers A and B, and the maximum value was 0.93 for observers B and C. With regard to intra-observer reliability, the kappa coefficients with linear weighting between the two evaluations of the same observer ranged between 0.86 and 0.95 for the Crowe classification and between 0.80 and 0.93 for the Hartofilakidis classification.

The reliability of both systems was substantial to almost perfect both for serial measurements by individual readers and between different readers, although the information offered was dissimilar.

We have assessed the long-term results of 292 cemented total hip replacements which were performed for developmental dysplasia of the hip in 206 patients. The mean age of the patients at operation was 42.6 years (15.9 to 79.5) and most (202) were women. The severity of dysplasia was graded according to both the Crowe and the Hartofilakidis classifications. A 22.25-mm Charnley head was always used and the acetabular components were inserted with cement into the true acetabulum. Bone grafting of the acetabulum, using the patient’s own femoral head, was performed on 48 occasions.

At a mean follow-up of 15.7 years (2.2 to 31.2) the overall survival of the acetabular component was 78%. The main cause of revision was aseptic loosening (88.3%). The rate of survival at 20 years based on the Hartofilakidis classification was 76% in the dysplastic, 55% in the low-dislocation and 12% in the high-dislocation groups and on the Crowe classification, 72.7% for group I, 70.7% for group II, 36.7% for group III and 15.6% for group IV. There was no statistical correlation between bone grafting of the acetabulum and survival of the acetabular component. This study has shown a higher rate of failure of the acetabular component with increasing severity of hip dysplasia.