An Experimental Study of Pathogenesis of Steroid-induced Avascular Necrosis of Femoral Head

Abstract：Objective: To explore the pathogenesis of avascular necrosis of femoral head( ANFH )and search an effective method for clinical practice. Methods: Twenty-four Japanese rab-bits were divided into 2 groups of models and controls. ANFH models were produced by intramuscular injection of large dosage of steroid to rabbits for 8 weeks. From the 4th, 8th and 12th week after pro-duction of models, 2 rabbits of each group were sacrificed to observe the structure of femoral headthrough light microscope and scanning electron microscope. The contents of Nitric Oxide (NO), tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) in plasma of the 4 rabbits in each group were estimated at the same time. Results: Compared with control group, the rabbits of model group exhibited many differences: such as osteoporosis of femoral head, the presence of morebone lacuna and fat cell tkrough light microscope observing; the broken and sunk bone trabecula, the loosen and broken collagen fibers on the surface of bone matrix through scanning electron microscope ob-serving. Compared with control group, the Concentration of NO and t-PA in plasma of the model rab-bits decreased obviously, but the Concentration of the PAI increased obviously. Conclusion: The steroid-induced ANFH might be related to the lower level of NO and the descent of fibrinolytic activity.