The thickness of the calcified layer of articular cartilage

The thickness of both the articular cartilage and its calcified zone were measured at 25 carefully selected points in 8 human femoral heads, and the ratio of one to the other was found to be remarkably constant for each bone. The thickness of the calcified zone therefore shows the same distribution pattern as that of the total cartilage and, since the latter is dependent upon the distribution of the load, the thickness of the calcified region also appears to be related to mechanical stress. The volume of the calcified zone, however, expressed as a percentage of the total cartilage, varied considerably from one bone to another within the range from 3.23 to 8.8%. Too few specimens were examined to allow correlation with age or sex to be either refuted or confirmed

The thickness of the calcified layer in different joints of a single individual

The thickness of the articular cartilage and its calcified zone were both measured at specially chosen places in several limb joints from five subjects. The volume of the calcified zone expressed as a percentage of the total cartilage was not only constant for one joint, but also in all the joints of a single individual. Nevertheless, the variation between subjects ranges from 6.9 to 8.6%. In two cases both sides of the body were investigated. As was the case in an earlier investigation on the femoral head, the bilateral distribution of the thickness was the same. Since the thickness of the total cartilage varies with the local distribution of loading in the joint, it follows that the thickness of the calcified layer also depends upon mechanical factors. Five subjects is too few to allow correlation with age or sex to be either refuted or confirmed. There is some evidence in the existing literature that the thickness of the calcified zone may be altered by diseas