The thickness of the cartilage in the hip joint.

The pattern of distribution of cartilage thickness in corresponding femoral heads and acetabula was ascertained in ten hip joints. The differences between individual acetabula and their corresponding heads were small enough for it to be admissible to calculate an average distribution pattern for head and socket. Comparison of these patterns showed that: (a) The maximum thickness is found at points in the ventrocranial area of the acetabulum and ventrolateral area of the head. (b) From these points the cartilage thickness decreases concentrically. (c) In the 'natural position' of the hip joint the points of maximum thickness of head and acetabular cartilage do not correspond. In relation to the line of the hip joint 'force resultant', the area with the thickest cartilage on the head is slightly shifted towards its medial side, and on the socket slightly to the lateral side. It is not possible fully to explain these results on the basis of existing conceptions about the functional stressing of the hip joint.