STUDY OF DIACETYLRHEIN IN AN EXPERIMENTAL RABBIT MODEL OF POSTCONTUSION OSTEOARTHRITIS

The ''chondroprotective'' activity of a drug must be tested not only i n vitro but also in vivo. Because this would require several years in humans, animal models of osteoarthritis are used. A closed contusion o f the patella caused by the impact of a 1-kg weight dropped from a hei ght of one meter results in osteoarthritis. Twenty-three adult New Zea land rabbits were sacrificed 49 days after the contusion. Cartilages o f both condyles and the patella were studied on 6-mu hematoxylin-eosin -stained serial sections. The morphologic osteoarthritis score (sum of gross and microscopic scores) was determined. Mean score was the mean value of scores for both condyles and the patella, whereas total scor e was the sum of scores at the three sites. The 23 rabbits were divide d into four groups: controls (n=6), controls + diacerhein (n=5), contu sion (n=6), and contusion + diacerhein (n=6). Diacetylrhein was given orally (3.5 mg/kg/d) throughout the 49-day interval between contusion and sacrifice. Mean and total scores showed no significant differences between the control, diacerhein, and diacerhein + contusion groups. S cores were significantly lower in the control group as compared with t he contusion group (p<0.03) and in the diacerhein + contusion group as compared with the contusion group (p<0.05). Diacetytrhein given in as prophylactic treatment under the experimental conditions used prevent ed contusion-induced cartilage destruction and exhibited a ''chondropr otective'' effect.