Effects of weight bearing on the tidemark and osteochondral junction of articular cartilage - Histomorphometric analyses of 7 normal femoral heads

To study the effect of weight bearing on the tidemark and osteochondral jun ction, we compared the morphology of these two boundaries in weight-bearing and less weight-bearing regions of normal human femoral heads. We measured the irregularities of the boundaries in the two regions using an X-Y digit izer connected to a computer in histological whole sections of femoral head s in 7 subjects without joint diseases. The irregularity of the tidemark was small, showing no difference between t he two regions. However, the irregularity of the osteochondral junction in the weight-bearing region was greater than in the less weight-bearing regio n, which was confirmed by three-dimensional reconstructed images. Our findi ngs suggest that mechanical stresses greatly influence the morphology of th e osteochondral junction compared to the influence of such stresses on the tidemark, and that the marked irregularity of the osteochondral junction in the weight-bearing region is a reactive phenomenon against mechanical frag ility due to simple contact between calcified cartilage and subchondral bon e without fibrous connections.