Comparison of the prophylactic use of ibandronate and its use in early-stage osteonecrosis in rats with steroid-induced osteonecrosis of the femoral head.

Objectives: The aim of this study was to investigate the effects of ibandronate before and after the onset of osteonecrosis in rats with steroid-induced osteonecrosis of the femoral head.

Materials and methods: A total of 24 female Sprague-Dawley rats were used in this study. Three groups were formed with eight rats in each group. The first group was the prophylactic group that received ibandronate treatment before and after the onset of osteonecrosis (Group PT). The second group received ibandronate treatment three weeks after the development of osteonecrosis (Group TAO). The third group was the control group in which osteonecrosis was created, but only normal saline (NS) was given. At the end of the study, all rats were sacrificed, and their right femoral heads were removed, fixed with formalin, and sent for micro-computed tomography. Hematoxylin-eosin (H&E) and immunohistochemical examinations of the right femoral head sections were performed.

Results: In the PT group, the trabecular thickness was significantly higher compared to those of the TAO and control groups (p<0.05). The trabecular thickness did not significantly differ between the TAO and control groups. The trabecular bone pattern factor was significantly higher in the PT group compared to the control and TAO groups (p<0.05); however, it showed no significant difference between the TAO and control groups. The incidence of type 2 osteonecrosis in the PT and TAO groups was significantly lower than that in the control group (p<0.05). The incidence of tissue-non-specific alkaline phosphatase (TNAPase) immunoreactivity of osteoblast positivity was significantly higher in the PT and TAO groups compared to the control group (p<0.05), whereas the incidence of TRAPase immunoreactivity of osteoclastic positivity was significantly lower in the PT and TAO groups compared to the control group (p<0.05).

Conclusion: Intravenous administration of ibandronate before the onset of the disease was more effective in the treatment of osteonecrosis in rats with steroid-induced osteonecrosis of the femoral head.