Abstract: Objective To observe the changes in parameters of coagulation-fibrinolysis systems in rabbits with steroid-induced avascular osteonecrosis of femoral head(SANFH) and to investigate the pathogenesis of SANFH.Methods Experimental animal and grouping:Male adult New Zealand white rabbits,ranging in weight from 2.5 to 3.5 kg,were obtained from experimental center of Capital Medical University and randomly divided into seven groups including Group N(normal group);Groups M24 h,M48 h,M1,M2,M4,M6(model groups).Eight rabbits for each group.Animal models of steroid-induced avascular osteonecrosis of the femoral head were established according to Yamamoto T et al's method.Animals in model group received lipopolysaccharide(LPS) 20 μg/kg intravenously 2 times at an interval of 24 hours,methylprednisolone 20 mg/kg injected were intramuscularly into the gluteus medius 3 times at intervals of 24 hours after the second injection of LPS.The plasma levels of antithrombin-Ⅲ(AT-Ⅲ),thrombomodulin(TM),tissue-type plasminogen activator(tPA) and plasminogen activator inhibitor-1(PAI-1) were measured in each group.Results 1) Coagulation system:AT-Ⅲ:Compare with the normal group,the plasma levels of AT-Ⅲ in the model group were significantly higher at 24 hours after the first injection of LPS(P<0.05),then began to decrease at 48 hours,most obviously at 1 week(P<0.05);TM:Compare with the normal group,the plasma levels of TM in the model group began to increase at 24 hours after the first injection of LPS(P<0.01),most obviously at 1 week(P<0.01).2) Fibrinolysis system:tPA:The plasma levels of tPA in the model group were significantly lower than those in the normal group from 24 hours to 2 weeks after the first injection of LPS(P<0.01);PAI-1:The plasma levels of PAI-1 in the model group were significantly higher than those in the model group from 24 hours to 2 weeks after the first injection of LPS(P<0.01).Conclusion Marked dysfunction of coagulation-fibrinolysis systems has been found in the model animals,which may be one of the pathogeneses of SANFH.

Key words: steroid, avascular necrosis of the femoral head, coagulation, fibrinolysis