The relation between cartilage damage and osteophyte size in a murine model for osteoarthritis in the knee.

The aim of this study was to investigate the relationship between location and size of osteophytes and cartilage loss in an instability-induced experimental model for osteoarthritis. Osteoarthritis was induced in murine knee joints by injection of highly purified bacterial collagenase, causing joint instability. The size of the osteophytes and the cartilage loss were measured at different locations in the joint using image analysis on histological sections of total kees. Cartilage damage did not occur without osteophytes. Osteophytes were located on both medial and lateral sides, independent of the location of cartilage damage, but the size of the osteophytes was related to the amount of cartilage damage on the corresponding side. Cartilage loss on the lateral tibial plateau correlated well with the size of lateral osteophytes, in particular with the osteophyte at the margin of the lateral tibial plateau. Cartilage loss on the medial tibial plateau appeared to have a good correlation with the size of medial osteophytes, which was most pronounced for the osteophyte on the medial margin of the tibial plateau. This side-specific correlation between cartilage damage and osteophyte formation suggests compartmentalization of the osteoarthritic process.