[A morphological study of degenerative mechanism of articular cartilage by abnormal high stress]

The articular cartilage from the right knee of 87 rats whose left calcaneal tendons had been transected was examined under transmission and scanning electron microscopes, and light microscope. Morphological observation showed a few small focal areas of cartilage surface disruption, pit and collagen fibrillation at 2 weeks after operation. After 1 month, many clusters of chondrocytes could be found, showing hyperactive synthetic and secretary activity. The cartilage degenerated progressively. The initial lesion in high stress side was at the matrix of cartilage, the collagen network was disrupted, then proteoglycan become degraded. The microenvironment of chondrocytes was changed with degradation of matrix. The chondrocytes became degenerative. The degeneration of chondrocytes influence the matrix again. A vicious cycle was thus formed. At the early stage of the degeneration of the cartilage induced by high-stress, som chondrocytes proliferate and have hyperactive synthetic and secretive functional activity. But soon, most of the chondrocytes degenerate. That is because of the chondrocytes have got repaired in response to initial matrix lesion and the normal microenvironment had degraded with aggravation of matrix lesion. These chondrocytes again became degenerative quickly.