Increased femoral anteversion and osteoarthritis of the hip joint.

The anteversion angle (AV-angle) of the femur was measured according to the method of Rippstein in a series of 50 patients with "primary" osteoarthritis of the hip, and in a control group of 30 individuals of the same age without hip disease. The median AV-angle of the hips in osteoarthritic patients was 17.5 degrees, and in the control group 13 degrees. Osteoarthritic patients had a significantly increased AV-angle in relation to the control group (P = 0.0028). The greatest AV-angle in the hips of the control group was 25 degrees. In 18 hips of osteoarthritic patients an AV-angle greater than 25 degrees was found. Osteoarthritis was found in 15 of these hips; there was no osteoarthritis in the remaining 3 hips. Our results lead to the conclusion that increased femoral anteversion is a predisposing factor for hip osteoarthritis. This implies that derotational osteotomy in children can be a prophylactic procedure.