[The treatment of hip dysplasia or dislocation with Fettweis' immobilization cast].

To verify the success of the cast immobilisation in a squatting position in the treatment of dysplasia and dislocation of the hip 41 children were reviewed whereby lapses up to 13 years had to be considered. In 9 hips the cast immobilisation leaded to an unsatisfactory result so that the joints had to be revised operatively. In the remaining 48 hips 31 (65%) were cured, 15 (31%) showed a light, 2 (4%) a grave remaining dysplasia. One hip joint showed an ischemic necrosis of the femoral head which corresponds to a rate of necrosis of 2.1%. As the concerned patient was treated with spreader pants in spite of the high grade of luxation of her hip it more likely that this avascular necrosis is caused by the preceding treatment and not by the cast immobilisation itself. Factors with negative effects on the result or bad prognostic signs respectively, were poor initial findings and reluxation during cast immobilization. The start of therapy had no noticeable influence on the result. On the other hand this factor was very important for the permanence of treatment. In hips with remaining dysplasia very often a clinical hypermobility was found. A positive Trendelenburg-sign was seen in the hip with defect-healed avascular necrosis of the femoral head and furthermore in 2 other hips with evident remaining dysplasia of the acetabulum. In comparison to other methods, the cast immobilisation according to Fettweis shows a low rate of avascular necrosis of the femoral head and a forced supplementary development of the dysplastic acetabulum. Because of its wide range of indication and its small rate of complications the Fettweis plaster cast is a very reliable method for the treatment of dysplasia and dislocation of the hip in infancy and early childhood.