Abstract: Objective: To study the articular cartilage injury in rabbits with knee osteoarthritis and the effects of calcitonin. Methods: 36 rabbits were randomly divided into three groups: normal group (group A), model group (group B) and CT treatment group (group C).There were 12 rabbits in each group. The rabbits in group B and C were made into knee osteoarthritis by Hulth’s method. The rabbits in group A weren’t dealed by special process, except for incision of skin and articular cavity. The rabbits in group C were interfered by hypodermic injection CT everyday (5∪/kg). The other rabbits were interfered by normal saline. The pathomorphism and changes of TNF-α, NO，collagen Ⅱ and MMP-1 were observed. Results: The scores of JP and Mankin in group B were significantly higher than those in group A, articular cartilage injury was more serious, meanwhile, the content of TNF-α、NO in synovial fluid increased (P＜0.05 ), the expression of MMP-1 increased, but the expression of collagen Ⅱ decreased (P＜0.05 ). Compared with group B, the scores of JP and Mankin in group C were significantly decreased, the articular cartilage injury relieved evidently, expression of MMP-1 and the content of TNF-α, NO in synovial fluid decreased significantly (P＜ 0.05 ), but the expression of collagen Ⅱ increased significantly (P＜0.05 ). Conclusion The protection of articular cartilage injury by CT on KOA may relevant to the inhibition of TNF-α and NO.

Key words: Knee Osteoarthritis, TNF-α, NO, Collagen Ⅱ, MMP-1, Calcitonin