Passive role of articular chondrocytes in the pathogenesis of acute meniscectomy-induced cartilage degeneration.

The importance of viable articular chondrocytes and enzymes or factors from surgically traumatized synovium in the pathogenesis of acute meniscectomy-induced cartilage degeneration was examined in guinea pigs (nine groups of five animals each). Iodoacetate injected intra-articularly was used to kill articular chondrocytes of guinea pigs prior to meniscectomy to determine if they were active participants in the acute lesion induction. Lesions of similar severity to those occurring in animals with viable chondrocytes at the time of surgery were observed, suggesting that the chondrocytes were not actively involved in the pathogenesis in this group. In an additional group of guinea pigs in which chondrocytes were killed by iodoacetate, the medial collateral ligament was transected to determine if acute degenerative changes could be induced in acellular cartilage exposed to a surgical manipulation that does not by itself induce lesions but does expose cartilage to enzymes/factors from traumatized synovium. Transecting the medial collateral ligament and entering the joint space without induction of instability via meniscectomy did not result in histologic evidence of cartilage damage. This suggests that synovial trauma and mild inflammation were insufficient to induce matrix degeneration in the absence of abnormal load bearing. In further support of this, guinea pigs subjected to unilateral sciatic neurectomy at the time of meniscectomy were protected against development of acute cartilage degeneration. Results of this study suggest that articular cartilage devoid of viable chondrocytes at the time of meniscectomy responds acutely in much the same way as intact cartilage subjected to this procedure.