THE EFFECT OF REMOVAL OF THE MEDIAL COLLATERAL LIGAMENT ON SUBCHONDRAL BONE AND CARTILAGE IN THE GROWING RAT KNEE-JOINT

The growing knee joint in immature rats was chosen as a model to study quantitatively bone apposition and thickness of articular cartilage a fter surgical removal of the medial collateral ligament. In 32 rats, s ubchondral bone apposition was assessed by measuring double tetracycli n labelling, and the thickness of calcified and uncalcified articular cartilage was measured by image analysis. The results indicate that th ere was a significant increase in subchondral bone growth after remova l of the medial collateral ligament, but no change in thickness of the calcified and uncalcified zones of the articular cartilage in the med ial knee compartment, Further, despite an obvious increase in valgus l axity on manual examination, there were no signs of articular cartilag e degeneration in any animal. The study shows that traumatic injury to ligaments and joint instability during the growing period may influen ce the development of subchondral bone in the knee joint.