A THERAPEUTIC PRINCIPLE OF QUESTIONABLE EFFICACY IN THE TREATMENT OF PERTHES-DISEASE

The reduction of hip joint forces is a generally accepted part of the conservative treatment of Perthes disease. To reach this effect with help of splints (e. g. Thomassplint and the following models) does not seem to be efficient enough even from a clinical point of view. Theoretical considerations of former investigations of other authors point out the insufficient effect of these splints regarding the hip joint force reduction during the weight bearing phase in walking. The effect of these splints during the non-weight bearing phase in walking with regard to the hip joint forces has not been investigated so far. Therefore this paper is dealing with the forces onto the hip joint during the swinging phase of the leg with a splint, shown in a simplified, mechanical model. The results reveal significantly higher hip joint forces if the splint is used compared to the physiological forces during the swinging phase which in a static situation rise up to twice the body weight. These joint loadings are important because they occur during hip flexion and therefore cause pressure on the ventro-cranial part of the head of the femur, a region which unfortunately is often involved in Perthes' disease and therefore especially vulnerable to these forces. From a biomechanical point of view the principle of reducing the hip joint forces with splints has to be abandoned.