Experimental study on mechanism of steroid-induced avascular necrosis of femoral head

The authors adopted an animal model to observe the pathogenic mechanism of steroid-induced avascular necrosis of the femoral head. Sixty-four white rabbits were divided into two groups: hydrocortisone acetate (8 mg/kg) was hypodermically given to 48 experimental animals and 0.32 mg/kg of normal saline to 16 rabbits for control. Two groups of animals were fed and kept in the same condition. The results showed that application of the steroid drug could produce fat degeneration and necrosis of osteocytes and fat embolism in the small blood vessels of the femoral head. The abnormal hypertrophied fat cells in the bone marrow compressed small veins in the femoral head resulting in blood stasis of the capillaries, thus growth and regeneration of the capillary were inhibited.