Dose-Related Effects of Steroid on the Experimental Arthritis in Rabbits

ABSTRACT

OBJECTIVE: To investigate dose-related effects of repeated intraarticular steroid injection on the experimental arthritis. METHOD: Twenty-four adult male rabbits received Zymosan A into their right knee joint for experimental arthritis. After a week, they were injected with 2 mg (group I; n=9), 10 mg (group II; n=7) or 20 mg (group III; n=8) triamcinolone acetonide into their right knee weekly interval for 4 weeks. We measured weekly changes of the weight and the mediolateral diameter of both knees for the calculation of edema index. 99mTechnetium pertechnate (99mTc) uptake measurement were performed before the first steroid injection and a week after the final steroid injection. All rabbits were sacrificed and histologic examinations of their proximal tibia were performed. RESULTS: A progressive weight loss and changes of edema index were evident for all rabbits (p0.05). In the histological findings, fibrillation-frayings and fissures of the surface were similar in all rabbits, but loss of nuclear stains and cyst formations were increased prominently in group III than group I (p<0.05). CONCLUSION: Low-dose repeated steroid intraarticular injections are safe and effective treatment in arthritis though no definite evidence of chondroprotection, and high-dose steroid injections accelerate degeneration of the arthritic cartilage.