Objective To observe the histological changes of cartilage in weight-bearing and non weight-bearing areas of the femoral condyle in patients with knee osteoarthritis,and to explore the pathological process of cartilage degeneration in knee osteoarthritis.Methods From August 2021 to September 2022,56 patients with primary osteoarthritis of the knee and varus deformity who were treated with total knee arthroplasty in the People's Hospital of Ningxia Hui Autonomous Region were selected as research objects.The femoral condyles were collected as clinical specimens,the articular cartilage with severe wear of the femoral condyle was used as the weight bearing area (observation group),and the articular cartilage with less wear of the femoral condyle was used as the non weight bearing area (control group),HE staining and safranine O staining were performed to observe the histopathological morphology of observation group and control group under microscope.The ultrastructural characteristics of the surface of observation group and control group were observed and compared by scanning electron microscopy.Results Macroscopic observation showed that in the observation group,the cartilage surface of the femoral condyle was obviously defective,rough and uneven,with some osteophytes formed at the edges,and cancellous bone sclerosis was visible in the subchondral bone.In the control group,the cartilage surface of the femoral condyle was smooth and flat,with clear and uniform color,and no osteophytes formed at the edges.HE staining showed that the number of chondrocytes in the observation group decreased significantly,the arrangement was irregular,the cell proliferation was abnormal,and the cells appeared in clusters.In the control group,the articular cartilage matrix was stained evenly,the number of chondrocytes was normal,the shape was complete and full,and the nucleus and cytoplasm were clearly visible.Safranine O staining showed that the morphology of chondrocytes in the observation group was significantly changed,the cartilage layer was fibrotic,and the cartilage matrix was lightly stained.The size and morphology of chondrocytes in the control group were normal,and the arrangement was relatively neat.The cartilage matrix was evenly stained,and the tide line was normal;Scanning electron microscope observation:In the observation group,the surface structure of articular cartilage was not clear,a large number of pores of different sizes were visible,collagen fibers were not shaped,and normal chondrocytes were rare;In the control group,the surface of articular cartilage was relatively flat,collagen fibers were in bundles and orderly arranged,and normal chondrocytes were visible.Conclusion The normal physiological function of chondrocytes requires a stable level of chondrocyte matrix metabolism.KOA patients have degenerative changes of knee joint cartilage due to changes in cartilage matrix caused by a variety of reasons.