Yukimasa Nishimura

Idiopathic necrosis of the femoral epiphyseal nucleus in rats.

To study the cause of osteonecrosis of the femoral head in spontaneously hypertensive rats, the site and mechanism of the occlusion of the blood vessels feeding the femoral head were investigated histologically and microangiographically. Tracing the blood vessels using serial sections revealed that the lateral epiphyseal vessels disappeared immediately before entry into the ossific nucleus. As the reparative process advanced, the blood vessels from the lateral side of the head entered the ossific nucleus again. To investigate the relationship between osteonecrosis and mechanical stress on the femoral head, some treatments to reduce mechanical stress were applied, and the frequency of the femoral head lesions, such as osteonecrosis, disturbed ossification, and abnormality of the growth plate, was compared among the groups of treatments for stress relief. The incidence of femoral head lesions was found to be directly proportional to the mechanical stress working on the area, as was evident from a decrease in the incidence of osteonecrosis as a result of reduction of mechanical stress. Thus, the obstruction of the vessels in the lateral part of the femoral head might result from the breakdown of cartilage caused by the mechanical stress on the femoral head.

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.

Septic Arthritis of the Knee Joint Followed by Common Cold in an Infant

We treated a comparatively rare case of septic arthritis of the knee joint followed by common cold in an infant, caused by β-lactamase-negative ampicillin-resistant H. influenzae (BLNAR). The patient was 9 months of age. Knee joint arthritis symptoms appeared following common cold and middle ear infection. We detected H. influenzae from the fluid of the knee joint, and from the effusion of the middle ear and throat. The results of bacteriological tests indicated BLNAR. It was treated by surgical drainage and antibiotics injection. BLNAR is rapidly increasing in recent years. BLNAR can therefore be suspected when infantile septic arthritis especially following common cold. In this case, it is very important to detect the joint fluid by bacteriological tests and carefully select the antibiotics to use without residual disability.