[Etiology and pathogenesis of epiphyseal necrosis in childhood as exemplified with the hip].

In many cases the etiology of juvenile necrosis of the femoral head has not been unequivocally explained. Essentially, however, it is due to reduced arterial blood flow, although venous congestion also has to be considered. Epiphyseal necrosis is frequently a result of known underlying diseases. These include, for example, both specific and nonspecific forms of coxitis and rheumatic coxitis, hormonal dysfunctions, metabolic disorders such as mucopolysaccharidosis, blood diseases (e.g. hemophilia, sickle cell anemia), leukosis, and tumors and necrosis following cortisone and cytostatic therapy. The following four factors may directly or indirectly cause arterial vascular damage and thus necrosis: 1) primarily exogenous and 2) primarily endogenous factors, 3) genetic, and 4) skeletal maturation factors. These etiological factors are described in detail and discussed. Epiphyseal deformation occurs in a strict sequence of five phases, which are described. It should be emphasized that while necrotic bone tissue is being gradually resorbed, deposits of new bone matrix are already accumulating on dead trabecula and will subsequently form new bone fibre. In other word, a gradual substitution takes place. Two important clinical facts derive from this. First, epiphyseal crash is not due to the load of the body's weight. Since active resorption takes place, there is no justification for weight-relieving therapy in the basic therapeutic concept for Perthes' disease. Second, in light of our studies, surgical containment therapy appears to be the most suitable form of treatment if performed at the right time, i.e. in the golden period of remodelling, depending on the patient's age, the extent of necrosis and the degree of dislocation. Where stringent criteria are fulfilled we perform a three-dimensional intertrochanteric osteotomy, i.e. an extension-derotation reduction osteotomy.