Neck metaphyseal angle guidance in proximal femoral varus osteotomy.

An angle within the femoral arch is defined, and its line is described in selecting the osteotomy site and the position of the fixation device in performing a femoral varus osteotomy. This neck metaphyseal angle was measured with varying degrees of rotation on seven pediatric femurs; it was also studied on 283 randomly selected hip radiographs. The angle varied 25-40 degrees in 90% of the patients and was not age related. The angle is stable within 5 degrees as long as the landmarks, base of the great trochanter, and medial metaphysis of the femoral neck are definable (0-30 degrees of rotation).