〔Abstract〕 Objective To explore the pathological characteristics of myogenic contracture and its possible mechanism in rabbit model of knee extension contracture. Methods According to the immobilization time, thirty New Zealand white rabbits were randomly divided into 5 groups(n=6): control group(I-0, without any treatment), 1-week immobilization group(I-1, with left knee joint complete extending immobilization for 1 week), 2-week immobilization group(I-2, with left knee joint complete extending immobilization for 2 weeks), 4-week immobilization group(I-4, with left knee joint complete extending immobilization for 4 weeks) and 8-week immobilization group(I-8, with left knee joint complete extending immobilization for 8 weeks). At the end of each immobilization time point, the rabbits were killed, and then the myogenic contracture and arthrogenic contracture were analyzed by detecting the angle of knee joint contracture after immobilization. The cross-sectional area of rectus femoris muscle fiber was analyzed by Masson staining. The protein expression levels of hypoxia inducible factor-1α(HIF-1α) and transforming growth factor-β1(TGF-β1) were analyzed by Western blot. Results During the 8 weeks, the angle of myogenic contracture in the immobilization group increased with the immobilization time within 4 weeks, but there was no significant difference between I-4 group and I-8 group after 4 weeks. Masson staining results showed that the cross-sectional area of rectus femoris decreased continuously within 4 weeks of immobilization, while the proportion of collagen fiber deposition increased continuously within 4 weeks after immobilization. However, there was no significant difference in the reduction of cross-sectional area of rectus femoris and the increase of collagen fiber deposition between I-8 group and I-4 group after 4 weeks of immobilization. The expression level of HIF-1α protein increased continuously within 4 weeks after immobilization, but there was no significant difference in the expression level of HIF-1α protein between I-4 group and I-8 group after 4 weeks immobilization; the expression of TGF-β1 protein increased significantly within 2 weeks, but there was no significant difference between the each group after 2 weeks immobilization. Conclusion The muscle fibrosis and atrophy are mainly pathological features of myogenic contracture in rabbit model of knee extension contracture, which is time-dependent change, and the mechanism may be related to the high expression of HIF-1α and TGF-β1.