The width of the weight-bearing surface (WBS) of the acetabulum and its obliquity; height, width, opening angle and alpha angle of the gothic arch; diameter of femoral head; the angle between the center of the femoral head and the most lateral point of the acetabulum (CE angle); neck-shaft angle (CCD angle); offset; angle of aperture, surface area, and volume of the spherical sector; radius and height of the spherical bowl; and distance from teardrop were assessed to study mechanically normal and frankly osteoarthritis hips. There appears to be a direct correlation between primary alterations of the above variables and development of osteoarthritis of the hip.