Whereas the glenohumeral joint functions mainly in an open kinetic chain position, the hip (coxofemoral) joint functions mainly in a closed-chain position. For this reason, its structure is one of stability for weightbearing. In the standing position, however, the joint is not fully congruent, the anterosuperior portion of the cartilage of the head being exposed. It is only when the joint is taken into a position equivalent to that of the quadruped (90-degree flexion, 5-degree abduction, and 10-degree lateral rotation) that maximum articular contact of the head with the acetabulum occurs.