An Animal Experimental Study Of Intervening The Steroid-induced Femoral Head Necrosis (SIFHN) By Pravastatin

Object : To build a model of rabbits' Steroid-induced Femoral Head Necrosis (SIFHN) by administing Dexamethasone(DEX). Discussing whether the Provastatine can intervening the course of resulting in SIFHN and the possible mechanism. Methods: The Japanese rabbits, 12-18 weeks old ,2.50.6kg, randomly divided into 4 groups, Group A(n=8): Just used as the control. Group B(purely administering DEX n=12).Group C(n=12): Pravastatin 5mg/d p.o. Group D(n=12): Pravastatin 10mg·d-1 p.o. Every rabbit of group A B C was fed by standard forage and fodder. DEX of 2.5mg·kg-1·d-1 was injeceted to the rabbits except Group A for 12 weeks. Simultaneity, the Penicillin-natrium 80,0000u and streptomycin 1.0g was injected to everyone ,twice a week, avoiding being infected. Every following 6,8,10,12 weeks, 3 rabbits of every group were selected to examined with serum cholesterol and triglyceride, hemorrhelogical factor, PT, tissue plasminogen( t-PA) and double hipcoxa joints were taken an X-ray photograph before they were executed . The specimens of double femoral heads were taken to studied by the light microscope after stained with Hematoxylin and eosin(HE), Transmission Electron Microscope(TEM) and analyse of apoptosis. Result: Comparing with the Group B, the serum cholesterol and triglyceride, hemorrhelogical factor levels of the Group C and D had lowered obviously, PT and t-PA are higher since 6 weeks (P<0.05),X-ray didn't show the phenomenons of the irregular radiolucent cystic area and ossificational cirrhosis that was found clearly in the subchondral region of the acetabulum and femoral head. Light microscopy exhibit the density of trabecular bone did not change more than Group A. The rate of the empty lacuna and the bone marrow stromal cell transforming to the lipocyte had decreased obviously . There is seldom fat embolus and lipid droplets appearing in the vessels of the osteocytes. Under the TEM, organelle and nucleus of osteocytes were found rarely degenerative, necrotic and swallowing the lipid droplets. The analyse of apoptosis present the AI(Apoptosis Index) was lower than Group B(P<005) .The effect of Pravastatin intervening the course of SIFHN did not show markedly difference between the Group C and D. Conclusion: The Dexamethasone resulted in building the model of rabbits' SIFHN as the Group B. and the Pravastatin can intervene the couse of SIFHN effectively .The mechanism of action is mightly related with lowering the level of serum lipid and hemorrhelogical factor, releasing the osteoporosis, which would reduce the obstructive possibility of blood supply and the rate of fracture that happened below the subchondral region of femoral head.