RESUMO
BACKGROUND:The rabbit model of osteonecrosis of the femoral head (ONFH) has been successfully established by glucocorticoid combined with lipopolysaccharide.OBJECTIVE:To observe the dynamic changes of bone mass in the early steroid-induced ON FH.METHODS:Twenty-four adult New Zealand white rabbits were randomly divided into experimental and control groups (n=12 per group).Rabbits in the experimental group were injected with lipopolysaccharide and glucocorticoid to establish the model of ONFH,while those in the control group given the same volume of normal saline.The changes in the femoral head structure,morphology and distribution of the trabecular bone at 5,1 0,15 and 20 days after modeling were observed through multi-slice spiral CT,micro-CT and hematoxylin-eosin staining;the bone mineral density and rate of empty lacunae were detected.RESULTS AND CONCLUSION:The imaging examinations showed that the rabbit femoral head was intact and smooth in both groups;on days 15 and 20,in the experimental group,the cortical bone became thinner,the trabecular bone became sparse and discontinuous,and the bone mineral density,tissue mineral density and bone volume/total volume were significantly lower than those in the control group (P ＜ 0.01).The histological observation indicated that there were more empty lacunae and adipocytes,as well as less osteocytes and hematopoietic cells in the experimental group;the rate of empty lacunae in the experimental group was significantly higher than that in the control group on days 15 and 20 (P ＜ 0.01).These findings suggest that in the early stage of ONFH,necrotic osteocytes increase in number,accompanied by trabecular micro-fractures,which leads to a decrease in bone mineral density,eventually resulting in bone remodeling disturbance.