Warfarin reduces the incidence of osteonecrosis of the femoral head in spontaneously hypertensive rats.

In this study, we investigated the effects of warfarin potassium on the incidence of the femoral head osteonecrosis in spontaneously hypertensive rats (SHR). Twenty-four SHRs were divided into two equal groups, one given normal water (water group) and another provided with water containing warfarin (warfarin group). We compared the two groups histologically and observed the incidence of osteonecrosis. We also studied 17 Wistar Kyoto rats (WKY) to compare with SHR. Coagulation time, platelet count, and protein C activity were measured. Immunohistochemistry was also performed using endothelial nitric oxide synthetase (eNOS) antibody to investigate the function of endothelial cells. The incidence of osteonecrosis was significantly less in the warfarin group (10.5%) than in the water group (52.6%). Coagulation time was significantly longer in the warfarin group than the water group. Platelet count and protein C activity were not statistically different between the warfarin group and the water group. Results of immunohistochemistry revealed that endothelial cells in the femoral head were positive for eNOS in WKY but not in SHR. Our results indicated that warfarin reduced the incidence of femoral head necrosis in SHR.