[The role of static-dynamic factors in genesis of femoral head and neck deformation in dysplastic hips. A physical-mathematical interpretation ].

The clinical material for a physical-mathematical analysis of femoral head and neck deformations in subluxated and luxated hips consisted of 1.574 case histories of children operated on in 1954-1988. In that material 21.9 per cent of the children had preoperative growth disorders of the head, and in the half of the cases also the femoral neck was involved. In 10.79 per cent of the children pre- and postoperative trophic disorders were also observed. On the basis of the physical-mathematical analysis of static-dynamic factors of the hip, it has been determined that the disordered shape of the femoral head and neck is most of all the result of defective formation of the roof. The oblique roof changes the static and dynamic forces acting on the femoral head and neck in such a way that large overloading of the growth zones of the medial side occurs and is followed by development of proximal femur deformation.