An Experimental Pathological Study Of The Early Influences Of Knee Joint Instability On Articular Cartilage Of Rabbits's Knee

Objective:To compare the content of collagen,proteoglycan and the apoptosis of chondrocytes on two model groups of knee joint instability, investigation the characteristics of histopathological early changes in articular cartilages in rabbits with knee joint instability.Methods:Sixty mature New Zealand white rabbits were the subjects of this study,and randomly divided into A group,B group and C group with 20 rabbits in each group.Rabbits in the A group underwent anterior cruciate ligament transecion only;transection of the medial collateral ligament and commplete medial meniscectomy of knee were performed in the B group;the C group were normal group.The specimens were collected on week 1,week 2,week 3,week 4,week 5 after operation,the rabbits were killed with aeroembolism.The medial femur condyles were resected in the sagittal plane,fixed in 10%buffered Formaldehyde and decalcified with 10%EDTA for 5 weeks at 4℃.Thereafter,they were embedded in paraffin, and serial sections(5μm) were cut in the sagittal plane.The sections were stained with hematoxylin and eosin(HE),Safranin O—Fast Green and elastica-Van Gieson staining for histological examination.Each sample was evaluated the cartilages histological characteristics according to the method of Mankin and Cartilage collagen fiber content in the average optical density measurement.For each of the groups,mean±SD values were determined in SPSS12.0.Group t-test for independent-samples was used to check for between different groups.Results:The changes in apoptotic chondrocytes were performed on knee joint instability model of different stages.Differences of Mankin score between two model's group and the normal group were significant,there were differences in the Mankin score between the group A in the 2,3,4,5 week or B any week and C(P＜0.05),especially the fifth week in the B group.In elastica-van Gieson staining,cartilage collagen fiber content in the average optical density measurement.There were differences in the Mankin score between the group A in the 3,4,5 week or B 2,3,4,5 week and C(P＜0.05).Conclusion:(1)In early knee joint instability,the articular cartilages degenerated extent is related to the chondrocytes apoptosis index.(2)The initial damage of the instability knee joint cartilage starts at the matrix of cartilage,the collagen network disrupts,and then proteoglycan is lost.The microenvironment of chondmeytes consists of changes with degradation of matrix.The chondrocytes become degenerated and necrosis presents from superficial to deep layer,and then affects the matrix again.(3)In order to avoid the negative influence on the knee by injury,we should treat the instability factor of knee joint in early stage.