[Avascular necrosis of the hip in radiologic images during treatment using the Freyka pillow for congenital hip dislocation].

Radiological picture of 823 hips in 636 children treated with the use of Freyka pillow between 1972 and 1976 was assessed. Avascular necrosis of the proximal end of the femur was found in 113 cases. The older the child was at the beginning of treatment the highest were the chances for developing avascular necrosis, but more serious changes were found in younger children. In the hips with greater initial dislocation changes were more frequent. A comparison between hips treated with Freyka pillow and those treated with different methods as to frequency of avascular necrosis was difficult due to the lack of uniformity in criteria for both diagnosis and assessment of the results.