Necrosis of the femoral head in growing rats. Occlusion of lateral epiphyseal vessels.

The cause of the vascular occlusion in necrosis of the femoral head of growing, spontaneously hypertensive rats was investigated histologically using serial sections. The lateral epiphyseal vessels, which supply the proximal femoral epiphysis, disappeared immediately before entry into the femoral heads. In fresh osteonecrosis the pathway of the vessels between the margin of the articular cartilage and the growth plate was replaced with granulation or scar tissue. We conclude that the vascular occlusion occurs in the layer of the epiphyseal cartilage where the lateral epiphyseal vessels penetrate, and that the abnormalities of the epiphyseal cartilage might play a part in the occurrence of osteonecrosis.