FEMORAL REMODELING AFTER SUBTROCHANTERIC OSTEOTOMY FOR DEVELOPMENTAL DYSPLASIA OF THE HIP

Children who present late with hip dislocation may require femoral ost eotomy after reduction, to correct valgus and anteversion deformity of the femoral neck. After these procedures proximal femoral growth is u npredictable. We have studied proximal femoral growth in 40 children w ho had been treated by femoral osteotomy. Preoperatively, the mean fem oral neck-shaft angle was 5 degrees greater on the affected side than on the contralateral side. Postoperatively, it was 28 degrees less. Th ere was progressive recorrection; after five years the angle was not s ignificantly different from that on the contralateral side. In our ser ies 70% of the capital epiphyses became abnormally shaped, taking the appearance of a 'jockey's cap'. All the growth plates became angulated but this corrected with time. Correction of the neck-shaft angle prob ably results from the more normal mechanical environment provided by r eduction. The abnormal radiographic appearance of the epiphysis and gr owth plate is probably due to the rotation produced by the osteotomy.