EFFECTS OF VALGUS TIBIAL ANGULATION ON CARTILAGE DEGENERATION IN THE RABBIT KNEE

Thirteen adult female rabbits underwent unilateral osteotomy of the pr oximal tibia. In nine animals. 30 degrees of valgus angulation was cre ated; in four animals, osteotomy without angulation was performed. Aft er a 12-week survival period, the knee joints were processed for histo logy by staining with hematoxylin and eosin and safranin O. Additional ly, the chondroitin sulphate epitopes 3-B-3(-) and 7-D-4 were evaluate d immunohistochemically as markers of osteoarthritis. Changes of the a rticular surface of the tibis were visualized by scanning electron mic roscopy. Light microscopic evaluation by the Mankin et al. scoring sys tem revealed mild or moderate damage of the cartilage in the lateral c ompartment of angulated extremities when compared with the control sid e. Immunohistology with the monoclonal 3-B-3 and 7-D-4 antibodies show ed no increased expression of these epitopes in the lateral compartmen ts of the knee. Scanning electron microscopic evaluation of the tibial surfaces revealed slight surface damage localized to the central, wei ght-bearing portion of the lateral tibial plateau of angulated extremi ties. Angulation of 30 degrees led to only mild degenerative changes o f the cartilage. These results indicate that, in the short term, carti lage has considerable capacity to withstand the effects caused by seve re angulation of the limb.