[Dysostotic changes and the prognosis of Perthes' disease after operation (author's transl)].

Goff and Mau for the first time demonstrated dysostotic changes in children with Perthes' disease. Their effect on the course of the disease has not so far been determined. It was examined on 41 patients following varus-osteotomy. Follow-up after 2--6 years showed late radiologic results, measured against the total quotient (Heyman and Herndon) depended essentially on this dysostotic component. The worst results are seen in children with high-grade skeletal retardation. Final results are further influenced by age, stage of the disease at the time of surgery and pre-operative status. Age plays a part in that results are better the younger the child. There are obvious parallels between results of radiologic and histologic examination at the time of operation and the weightbearing capacity. Dysostotic changes prolong the course of Perthers's disease and cause long-term lack of firmness of the femoral head. The influence of these facts on the still controversial indication for surgery is discussed. Our findings suggest that protection against weightbearing should be prolonged after operation according to the dysostotic changes.