[Histological study on spontaneous osteoarthritis of the knee in C57 black mouse].

The purpose of this study was to investigate the initial changes and pathological process of osteoarthritis in male C57 black mice (Silberberg), which develop spontaneous osteoarthritic lesions in the knee joints. The initial event in the development of the lesions was the slight loss of glycosaminoglycans in the articular cartilage matrix of the tibia, adjacent to the free margin of the anterior segment of the meniscus at 3 months of age. Microscopy under polarized light revealed irregularity of the tangential layer in the corresponding area at 6 months of age. Horizontal cleft along the tidemark, defect of cartilage and eburnation of subchondral bone later developed. Osteoarthritic changes were observed in all mice aged 18 and 24 months. However, no fibrillation of the cartilage matrix, chondrocyte clustering, osteophyte formation or synovitis was observed, probably because of the small joint and poor reparative ability in the mouse.