Abstract:

BACKGROUND: With the widespread use of steroid hormone, the incidence of steroid-induced osteonecrosis remained high, but the pathological mechanism of human femoral head avascular necrosis is unclear.
OBJECTIVE: To establish a model of steroid-induced osteonecrosis of femoral head and to discuss the effects of low dose of steroid in New Zealand white rabbits.
METHODS: Thirty rabbits were randomly divided into two groups. The experimental group rabbits received intramuscular injection of 4 mg/kg methylprednisolone sodium succinate; the control group rabbits were injected with the same amount of physiological saline at the same time. The venous blood reticulocytes were extracted for serological testing before and at 4, 6 and 8 weeks after exsangquinations. At 4, 6 and 8 weeks after steroid administration, histopathology of femoral head was performed and these rabbits were euthanized in batch.
RESULTS AND CONCLUSION: During the experimental process, one rabbit in the experimental group died. A total of 29 rabbits were involved in the analysis of results. During experimental course, the experimental group rabbits exhibited depressed consciousness and reduced activities and decreased weight loss (P < 0.05) after steroid administration. During the 4th week after administration, cells in the marrow cavity expanded and multiplied in number, which could be observed through the use of light microscope, and the percentage of fat cell size was higher compared with the control group (P < 0.05). At the 6th week, bone empty lacunae percentage was increased compared with the control group (P < 0.05). At the 8th week, the bone trabeculae of the experimental group were reduced and disordered, and disconnected, bone trabecular area percentage was decreased compared with the control group (P < 0.05), and there were parts of sequestrum and collapse in the area of cartilage. At the 8th week, total cholesterol level in the experimental group was significantly higher than that in the control group (P  < 0.05). At the 4th week, total triglycerides and low density lipoprotein level in the experimental group was significantly higher than that in the control group (P  < 0.05); high density lipoprotein level was significantly higher than that in the control group (P  < 0 .05). At the 6th week, serum level of alkaline phosphate was significantly increased compared with the control group (P  < 0.05). Osteobecrosis of femoral head can be induced by low dose of steroid in rabbits.