Objective To observe the therapeutical effect of hydropathic and hot compression of activating blood and diffusing impediment decoction(HCTCM) on knee osteoarthritis(KOA) in rabbits and to investigate its possible mechanism. Methods We randomly divided 72 rabbits into 6 groups(n=12) :the blank group, model group, Diclofenac Diethylamine Emulgel(DDE) group, HCTC 42°C group, HCTCM 37°C group, and HCTCM 32°C group. Except the blank group, we adopted the plaster tube fixation to make rabbit KOA models which needed 4 weeks in the other five groups. At the 5 th week, rabbits in the DDE group were treated with DDE on the right side of the knee joint, once a day; the rabbits in the HCTC 42°C group, HCTCM 37°C group, and HCTCM 32°C group were all treated with HCTCM, and the temperature at hydropathic and hot compression was adjusted to 42,37,32 °C, once a day; After 4-week intervention, the rabbits in each group were executed, and we observed the general situation and pathological changes of the right knee joint. The cartilage tissues of the right knee joint of each group were collected to detect expression level of Wnt3a, wnt5a and Wnt7a mRNA by real-time PCR, and the protein expression of β-catenin and glycogen synthase kinase 3β(GSK-3β) by Western blotting. Results Pathological examination in the blank group showed that the general condition of the right knee cartilage and the cartilage tissues were normal, and the model group showed obvious osteoarthritis changes. The joint surface of the HCTC 42°C group was smooth, with mild joint swelling and synovial congestion, meanwhile, there were more chondrocytes, the distribution was relatively uniform, and it could be stained, and the tide line was blurred but had layers.In the DDE group, HCTCM 37°C group, and HCTCM 32°C group, the surface of articular cartilage was uneven, accompanied by swelling and synovial congestion;the number of chondrocytes was small, the distribution was chaotic, there was localized cell accumulation, and the tide line was blurred. The relative expression of Wnt3a, wnt5a, wnt7a mRNA and the relative expression of β-catenin and GSK-3β protein in the cartilage tissues of the knee joint of the blank group, HCTC 42°C group, HCTCM 37 °C, control group, HCTCM 32°C group, and model group increased in turn, and the difference was statistically significant between groups(all P<0.05). Conclusion HCTCM is effective in the treatment of rabbit KOA, with the best treatment effect of 42 °C, and its mechanism may be related to the regulation of Wnt/β-catenin signaling pathway. [ABSTRACT FROM AUTHOR]