ObjectiveTo establish rabbit knee joint cartilage injury models to evaluate effects of the type Ⅱ collagen sponge in repair of the articular cartilage.MethodsThe type Ⅱ collagen sponge was prepared according to previous method and the pore size of the sponges was measured based on the collagen autofluorescence characteristics.The type Ⅱ collagen sponge was transplanted into the injury lesions of the animal model for experimental study.The regeneration of the cartilage defects was observed by using MRI, histologic HE staining, Safranin O, sirius red polarized light staining, areas determination of the newly grown cartilage and immunohistochemistry of type Ⅱ collagen.ResultsAutofluorescent images of confocal microscope layer scanning showed that the pore size was (93.26 + 38.40) μm in diameter, suitable for chondrocyte growth.Comparison between MRI and H&E staining results showed quicker effusion absorption in the treatment groups than that in the control group, while the level of inflammatory response in the treatment group was lower than that in the control group.The sporadic cartilage signals first appeared at the 6th week.The newly formed cartilage with the expression of glycosaminoglycan and type Ⅱ collagen matrix was confirmed by Safranin O staining and immunohistochemical analysis.The sirius red polarized light staining showed that areas of the newly formed cartilage were significantly larger in the treatment group than that in the control group (P ＜ 0.01).Conclusion The type Ⅱ collagen sponge developed from purification can effectively repair the damaged cartilage tissues of the rabbit knee joints, as has been verified either by MRI or histology.