Localized regressive articular cartilage changes in the hip joint of the rabbit following an induced synovitis.

A talcum induced synovitis in the hip joint of the rabbit, which is known to cause articular cartilage hyperplasia followed by femoral head protrusion and joint incongruency, has in the present experiment also been shown to lead to localized regressive articular cartilage changes. The articular cartilage of the hip joints in 40 rabbits was examined histologically, at intervals, following induction of such a talcum synovitis. Regressive changes in the form of loss of surface chondrocytes and glycosaminoglycans sometimes accompanied by fibrillation, were found in the area of the femoral head articular cartilage which had become flattened following the head protrusion. Chondrocyte cloning facilitated subsequent cartilage repair. The biomechanical disturbance in the joint following the induced synovitis is felt to have caused the regressive changes. The experiment is considered to have some significance in connection with Legg-Calvé-Perthes' Syndrome (L.C.P.S.) in children.