[Decreased acetabular anteversion and femur neck antetorsion cause pain and arthrosis. 2: Etiology, diagnosis and therapy].

ETIOLOGY: Differences in the anteversion of the acetabulum and the femur must be attributed to the different rotational postures of the fetus as investigations and experiments have shown. After delivery there is a spontaneous improvement, but in perhaps 15% of the joints, diminished or increased acetabular or femoral anteversion will persist during later life. The results of the investigation of Part 1 are compared with the literature. So far no correlations between AA/FA and different clinical consequences have been reported. The deformity of diminished AA and FA is found as a singular entity, also as one of the causes of slipped capital femoral epiphysis. It is frequently combined with coxa vara, also with deep acetabula and occasionally with developmental hip dysplasia and children with PFFD.

DIAGNOSIS: A hint for diagnosis is the limited range of internal rotation and an excess of external rotation of the hip besides some changes in the projection of femur and acetabulum. A CT in prone position with a summation of tomographic slices of the femoral neck and other details are necessary to measure AA and FA correctly.

THERAPY: Therapy is indicated when pain occurs and osteoarthritis is developing. Decreased femoral anteversion is corrected by rotational osteotomies. Significant differences of acetabular anteversion are treated by rotation of the acetabulum after triple pelvic osteotomy. The normal value of acetabular and femoral anteversion to be achieved is 15 to 20 degrees.