Study on the surface shape and contours of the femoral head and acetabulum of the human joint.

(1) The degree of change and degeneration of the surface of articular cartilage were classified into 6 stages and a distribution chart indicating 6 stages of classification was prepared for each case. (2) The construction of the superficial fine fibrous net-work of the cartilage of the weight-bearing area is different from that of the non-weight-bearing area. (3) The construction of the fiber underneath the surface of the acetabular cartilage is different from that of the surface of femoral head cartilage underneath. (4) When only weight-bearing part was compared, the degeneration at the upper anterior side was least for both femoral head and acetabulum and was most at the slightly posterior part of the upper outer side. (5) The fine fiber of superficial layer of the femoral head and acetabular cartilage were peeling from the periphery toward the center, but no difference of surface roughness was observed by way of measurement directions. (6) Surface roughness of the cartilage increases in proportion to the degree of degeneration and change. (7) The surface roughness of the acetabulum is about twice as large as that of the femoral head cartilage, this being due to the difference in the degree of degeneration. (8) There are 4 kinds of undulations at the surface of the femoral head cartilage. (9) Both femoral head and acetabulum have less waviness of large size at the part bearing large weight. (10) The contour of the femoral head as a whole is slightly ellipsoidal, whose longitudinal axis extends in a craniocaudal direction but the weight-bearing part is nearly circular. (11) The general contour of the acetabulum indicates an ellipsoidal shape with its craniocaudal longitudinal axis slightly inclined forward or backward. The contour of the slightly postero-upper part which is considered to be the maximum weight-bearing part is slightly flat ellipsoidal.