Recent advances in animal models for evaluating chondroprotective drugs.

While a variety of animal models have been described to evaluate the effects of antiarthritic and chondroprotective drugs on cartilage metabolism, most cannot be said to truly reproduce the temporal changes that occur in human osteoarthritis (OA). Total meniscectomy is a common orthopedic procedure in humans and frequently leads to OA in later years. We investigated the effects of unilateral medial meniscectomy in sheep knee joints subjected to moderate regular exercise. Morphological and biochemical studies of joint cartilage after 6 months revealed slowly progressive changes similar to those seen in early OA, characterized by cartilage fibrillation, chondrocyte hypertrophy, matrix proliferation and marginal osteophyte formation. The proteoglycans synthesized contained more chondroitin-4-sulphate than chondroitin-6-sulfate.