Objective: To explore the anti-injury effect of Zhuanggu Yihao Fang on osteoarthritis (OA). Method: The OA rat model was induced by sustained releasing agent (4% Papain and poloxamer).0.05 mL of the sustained releasing agent (4% Papain and poloxamer) was injected into both knee joint compartments of male SD rats to injury cartilage for a period of 2 h at 50 ℃. Besides normal group

the rats with osteoarthritis were randomly divided into 6 groups:model group (isovolumic distilled water)

glucosamine group (0.03 g·kg-1)

Zhuanggu Guanjie pill(1.10 g·kg-1) group and Zhuanggu Yihao Fang (2.20

1.10

0.55 g·kg-1) groups. The rats with osteoarthritis received daily oral treatments of drugs for 8 weeks. The normal group and the model group received daily oral treatments of isovolumic distilled water for 8 weeks. The contents of matrix metalloproteinases-3(MMP-3) and tissue inhibitar of metalloproteinases-1(TIMP-1) in synovial fluid were detected by enzyme-linked immunosorbent assay (ELISA). The changes in cartilages were evaluated by histopathology and morphometry. Result: MMP-3/TIMP-1 level in normal group was 0.062±0.011

compared with the normal group

MMP-3/TIMP-1 level in the model group was significantly increased to 0.092±0.010(P<0.05).After 8 weeks' treatment

the MMP-3/TIMP-1 level in Zhuanggu Yihao Fang (2.20

1.10

0.55 g·kg-1) groups was 0.060±0.016

0.060±0.028

0.057±0.027

respectively. Compared with the model group

Zhuanggu Yihao Fang (2.20

1.10

0.55 g·kg-1)treatments significantly reduced the MMP-3/TIMP-1 level (P<0.05

P<0.01). Compared with the normal group

the area of cartilage necrosis in the model group was significantly increased to (37 734±11 504) μm2 (P<0.01)

Zhuanggu Yihao Fang (2.20

1.10 g·kg-1)treatments significantly reduced the areas of cartilage necrosis in OA rats

which was (26 601±6 506)

(27 061±10 425) μm2

respectively (P<0.05). Conclusion: Zhuanggu Yihao Fang can protect the cartilage from injury and attenuate the progression of OA.