Bone replaces articular cartilage in the rat knee joint after prolonged immobilization

Bony replacement characterizes articular cartilage degeneration of knees immobilized for 32 weeks in the anterior, non-weight bearing region of the tibia. Replacement of cartilage by bone may have been mediated by chondral vascularization, suggesting irreversible changes. These findings stress the importance of weight-bearing and joint motion to maintain cartilage structure.