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

Objective: Pietrogrande and Mastonmarino reported one case that the avasular necrosis of the femoral head caused by the glucocorticoid in 1957.Thereafter,reports about the steroid- induced femoral head necrosis(SIFHN) gradually increased and received an increasing attention. In recent years,the Increasing incidence rate of hormone-induced necrosis of femoral head, SIFHN become one of common clinical diseases.Because the pathogenic mechanism of SIFHN is not clear,there is not an effective approach for treatment, inducing the disease worse. About one half of the patients involved double sides of the femoral head.In the late stage, patients are treated with artificial total hip joint replacement. It is a focus that periodic using of the prophylactic to the high risk group using hormone must be implemented e leading to reducing sickness rate.It is important to adopt flexible treatment methods to the patients of ANFH resulting in checking the progress of disease.This experiment is to build a model of rabbits'SIFHN by administing dexamethasone sodium phosphate(DEX).Discussing whether the alendronate sodium(AS) can intervening the course of resulting in SIFHN and the possible mechanism. Methods: The 64 Zelanian rabbits, 12~18 weeks old,2.5±0.6kg,randomly divided into 4 groups. Blank control group (Group A): n=16,Just used as the control. Pure hormone group (GroupB): n=16, purely administering DEX. Experimental group(Group C) divided into two groups: Experimental group1(Group C1): n=16, AS 5mg/d p.o. Experimental group2(Group C2): n=16, after using DEX two weeks, take AS 5mg/d p.o. Every rabbit of each group was fed by standard forage and fodder.DEX of 2.5mg/kg/d, was injeceted to the rabbits except Group A for 12 weeks. Simultaneity,the Penicillin-natrium80,0000u was injected to everyone,twice a week,avoiding being infected.Every following 4, 6, 8, 12weeks, four rabbits of each group were selected to examined with the triglyceride,and double hip joints were taken an X-ray photograph before they were executed.Every group,2 femoral heads were taken to studied by the light microscope after stained with Hematoxylin,eosin(HE) and the rest of the 6 femoral heads takes the analysis of pressure overload.All experiment datas were showed by mean±std( x±s)and were calculated by spss12.0 software, single factor analysis of variance was adopted in inter-group comparison, and nonparametric test was done in heterogeneity of variance (α=0.05).Results:①During the experiment the blood lipids in group B was significantly higher than group A(P<0.05).The blood lipids in group C was also significantly higher than group A(P<0.05). The difference between the group B,C1 and C2 were not significant.②After using the DEX 4 weeks in group B, X-ray features of bilateral femoral head are osteoporotic,thin bony cortex,blurred bone trabecula. It could be appeared that the cartilage surface are some degree of subsidence in 12th week. the bone trabecula was disordered.After 4 weeks,group C2 presented osteoporosis at different degree and small points or small pieces of lucency shadows.Hardened layer,cartilage surface and the change of joint space were not founded in 8th week.In 12th week,the degree of osteoporosis was more serious,but it was not appeared that the surface of articular cartilage was subsidence.The change of x-ray manifestations of the group C1 in the 4th week was not obvious.In the 12th week, the bone trabecula was blurred and there was not subsidence of the articular cartilage.③Light microscope observation,during the experiment, bone cell necrosis in group B presented karyopyknosis,karyolysis, karyorrhexis.The percentage of empty osteocyte lacuna elevated.Stimultaneously, subchondral bone is humble and continuity fragments. Bone marrow were degeneration,dissolution and necrosis with stenosis of vessels. There were thrombosis and fat emboliin the vessels. In group C1, cartilage of femoral head became thinning out and the trabecula was sparse and thin. There was no change in vacuoles of cartilage lacuna. Subchondral bone was continuous with small osteonecrosis. The degree of empty osteocyte lacuna and the trabecula in the group C2 was between the group B and the group C1.④The pressure overload experiment, the maximum pressure of femoral head in the group B were lower than in the group A.The maximum pressure of femoral head in the group C1 were higher than in the group B, but lower than in the group A.The difference has significant meaning,(P<0.05).The difference between group C1 and C2 has not significant meaning(P>0.05).Conclusion: The DEX resulted in building the model of rabbits'SIFHN as the Group B.And the Diphosphonate can intervene the couse of SIFHN effectively.The mechanism of action is mightly related with effecting the activity of osteoclast,reducing bone resorption and the osteoporosis,which would reduce the incidence rate of SIFHN and check the progress of the disease.