HISTOMORPHOMETRIC AND BIOCHEMICAL EFFECT OF VARIOUS HYALURONANS ON EARLY OSTEOARTHRITIS

Objective. To evaluate, histomorphometrically and biochemically, diffe rent protective effects of clinically used hyaluronans (HA). Methods. An experimental osteoarthritis (OA) model was applied to 132 mature NZ W rabbits by resecting the unilateral anterior cruciate ligament (ACL) . The other knee, where ACL remained intact, served as the control. We used native HA with different molecular weights, HA-50 (MW 5-7.3 x 10 (5)), HA-80 (MW 8 x 10(5)), HA-360 (MW 3.6 x 10(6)), and crosslinked H A (HA-CL). HA were injected into the joint once a week for 5 weeks (HA -50, HA-80, HA-360) or 3 weeks (HA-CL) beginning 4 weeks after ACL tra nsection. Histomorphometric and biochemical assessment was performed 9 weeks post-transection for both the HA treated and nontreated groups. Results. In gross morphological observation, cartilage degeneration w as suppressed in IIA treated groups, and this effect was superior in t he groups receiving either HA-sO or HA-CL. Histomorphometric and bioch emical analyses of the articular cartilage revealed similar results: t he HA80 and HA-CL groups showed no significant differences between the ACL transection and the control knees by histomorphometric variables, while the nontreated groups revealed significant degeneration. These evaluations were done in unblinded fashion. Biochemical analyses, incl uding DNA synthesis in the synovium, also showed that articular cartil age and synovium in the HA-80 and HA-CL groups did not present signifi cant changes compared to controls. Conclusion, In quantitative evaluat ion of this short term study using the OA model, native HA-80 and HA-C L presented a superior cartilage protective effect compared to the oth er native HA.