Joint distraction in treatment of osteoarthritis - (II): effects on cartilage in a canine model

Objective: From a clinical point of view, joint distraction as a treatment for osteoarthritis (OA) of hip and ankle has been demonstrated to be very p romising. Pain, joint mobility and functional ability, the most important f actors for a patient with severe OA, all improved. Although radiographic jo int space enlargement in a significant number of patients suggested cartila ge repair, actual cartilage repair remains difficult to evaluate. Therefore the present study was initiated to evaluate the actual effects of joint di straction on cartilage. Methods: For this purpose a canine model for OA, anterior cruciate ligament transection (ACLT) was used. Sixteen weeks after ACLT articulating Ilizaro v joint distraction of the knee was carried out. Absence of mechanical cont act between articular surfaces and presence of intra-articular intermittent fluid pressure, characteristics of Ilizarov joint distraction, were confir med. Twenty-five weeks after ACLT joint tissue of the dogs was analyzed. Results: Biochemical analysis showed that after joint distraction the abnor mal cartilage proteoglycan (PG) metabolism, characteristic for OA, had chan ged to a level found in control joints. Moreover, a mild degree of inflamma tion, present after ACLT, was reduced upon joint distraction. PG-content an d histological cartilage degeneration had not (yet) improved within the tim e of treatment. Discussion: Results suggest that the promising clinical results of Ilizarov joint distraction in patients with OA are accompanied by changes in cartil age metabolism. A change in proteoglycan turnover, indicating normalization of overall chondrocyte function, might in the long term, with normal joint use, lead to actual repair of cartilage. (C) 2000 OsteoArthritis Research Society International.