Treatment of Osteoarthritis of the Hip by Corrective Osteotomy of the Greater Trochanter

Abstract

The spacial relationship of the greater trochanter to the center of rotation of the hip, or the center of the femoral head, has a profound influence on the forces acting about the hip joint. Under normal anatomic and functional conditions the tip of the greater trochanter is level with the center of the femoral head. The length of the femoral neck, which acts as a lever arm to transmit forces about the hip, varies with body size and habitus. As a general rule, however, the distance from the tip of the trochanter to the center of rotation of the hip, which corresponds roughly to the length of the lever arm of the pelvitrochanteric muscles, is equal to the diameter of the femoral head (Fig. 1). In the horizontal plane, because of the physiological anteversion of the neck, the greater trochanter is 15° posterior to the center of the femoral head. On X-rays the tip of the greater trochanter appears to lie about 20° posterior to the midline of the femoral neck. Because the center of insertion of the pelvitrochanteric muscle mass on the greater trochanter is approximately in line with the femoral neck axis, in biomechanical terms the line of action of these muscles in the horizontal plane corresponds roughly to the ante-version of the femoral neck.