Hip joint congruence: experimental studies.

Three-dimensional imaging of hip joint preparations was carried out by means of computed tomography (CT). On the assumption that the head of the femur and acetabulum are incongruent, a special experimental design was used to quantify the extent and direction of the gliding movement of the head and socket. A series of CT images in the supine and prone positions was made from hip preparations, and the cartilage was visualized by injecting a contrast medium. In all the preparations dorsal movement was noted in the supine position, and ventral movement in the prone position. Cryomicrotome slices of the hip preparations were used to verify the results of our CT scans and the measurements correlated with the anatomical examinations. Thus, there is a certain amount of play in the hip joint-it is not an ideal ball-and-socket joint. This knowledge is important for the planing and success of hip adjustment surgery.