Introduction Hip growth continues on till adolescence with the fusion of the different ossification centers. Does this growth exist in hip dysplasia ? What is the role of surgery at adolescence ? Is an additional varus osteotomy indicated with a pelvic osteotomy ? Material and methods Clinical and radiological criteria of adolescent hip dysplasia were studied in a series of 18 patients (mean age 12 years). The 28 hips were divided into 4 groups depending on the treatment : non operated hips (group 1, N = 8), hips operated on only by pelvic osteotomy (group 2, N = 8), hips operated on by combined pelvic and femoral osteotomies (group 3, N = 9), and hips operated on only by femoral osteotomy (group 4, N = 3). Tonnis's clinical criteria were used. The acetabular index of the weight bearing zone, the center-edge angle of Wiberg, the acetabular angle of Idelberger and Frank, the neck-shaft angle, the head coverage index were measured and compared between the 4 groups (average follow-up was 46 months). Results We noted continuation of growth of the acetabulum at adolescence with a correction of moderate hip dysplasia when the head was covered (group 1), the acetabular index of the weight-bearing zone decreased from 20,1 degrees to 11,1 degrees; the center-edge angle of Wiberg increased from 15,25 degrees to 23 degrees. The comparison of groups 2 and 3 showed that an additional femoral osteotomy does not change significantly the radiologic results. Discussion Does surgery benefit at adolescence from the growth which exists during this period ? The clinical results and the evolution of arthrosis following a Chiari pelvic osteotomy are better when the operation is performed early. Conclusion A pelvic osteotomy is indicated in symptomatic hips, when the congruity is abnormal, with deficient head coverage, as well as moderate dysplasia when the evolution of the acetabular parameters are not satisfactory. A femoral osteotomy in addition to a pelvic osteotomy does not seem justified.
