[An experimental study on osteocyte apoptosis in steroid-induced early osteonecrosis of femoral head].

Objective: To explore the significance of osteocyte apoptosis in steroid-induced osteonecrosis of the femoral head.

Methods: Sixty New Zealand rabbits were divided into experimental group and control group (n=30). The experimental group was given 10 ml/kg of horse serum intravenously 2 times at 2 weeks intervals and an intraperitoneal injection of 45 ml/kg x d of methylprednisolone acetate for 3 days; the control group was given equal isotonic Na chloride. Osteocyte apoptosis was observe by means of TUNEL.

Results: The number of apoptosis in the experimental group (112.33% per hundred +/- 26.12% per hundred) was significantly higher than that in the control (47.01% per hundred +/- 22.95% per hundred) (P < 0.01) in the 4th week. With time, osteocytes apoptosis progressively increased. In the 6th and 8th weeks, the percentage of empty osteocyte lacunae in the experimental group (17.23% +/- 3.44%, 28.56% +/- 3.45%) was significantly higher than that in the control group (11.29% +/- 2.89%, 11.26% +/- 2.75%, P < 0.05). The transmission electron microscope showed that the characteristics of osteocyte apoptosis included intact nuclear membrane,c omdensed chromatin and increased electron dense.

Conclusion: Osteocytes apoptosis may play a key role in the process of steroid-induced early osteonecrosis of the femoral head.