Sulphate Metabolism of Articular Cartilage after Surgical Interference with the Joint.

In human osteo-arthritis there is a loss of matrix ground substance in the fibrillated cartilage (Matthews, 1953; Collins and McElligott, 1960). Studies using radioactive sulphate have indicated that the loss of ground substance is accompanied by a reactive increase in the synthesis of sulphated matrix by all but the more superficial chondrocytes in fibrillated areas (Collins and McElligott, 1960; Collins and Meachim, 1961). In the rabbit, changes in some respects similar to those of human osteo-arthritis have been induced experimentally by light scarification of the femoral articular surface (Meachim, 1963). This procedure was followed by loss of ground substance in the damaged areas and by a reactive increase in sulphated mucopolysaccharide synthesis, especially by the more superficial chondrocytes near the cuts. The situation differed from that seen in human osteo-arthritis in that the reactive response was more transient and in that the superficial chondrocytes now took part in this response. One obvious objection to experiments involving scarification is the absence of a history of direct trauma to the cartilage in most cases ofhuman osteoarthritis. In the studies now reported an experimental situation has been found in which a local alteration in sulphate metabolism of a cartilage has followed operative procedures not directly injuring it, namely, interference with the opposing articular surface or the insertion into the joint cavity of a piece of cartilage or plastic.