Effects of Zoledronic Acid and Vitamin E on Surgical– Induced Osteonecrosis of the Femoral Head in Rabbit

Background: Femoral head osteonecrosis is a progressive disease with disabling outcomes in hip joint if not treated. This study was designed to compare the effects of zoledronic acid plus vitamin E versus zoledronic acid alone in surgical induced femoral head osteonecrosis in rabbits. Methods: 26 Japanese white adult normal male rabbits at 28-32 weeks old were undertaken surgical femoral dislocation to devastate the femoral neck vessels; the femoral neck vessels were ligated and the hip was relocated. Next, the first 10 rabbits received zoledronic acid injections at 1st and the 4th weeks; the second group (10 rabbits) received zoledronic acid injections at 1st and the 4th week along with daily oral vitamin E for 12 weeks; and the third group was considered as non-treated control group. Radiographic and postmortem pathological assessments including the Ficat classification, epiphyseal quotient (EQ), new bone formation, and residual necrotic bone (RNB) were performed and compared after week 12. Results: A significant difference was found between the combination therapy group and the control group in Ficat classification at 12th weeks (P=0.048), but, the difference between monotherapy and combination therapy groups at 12th weeks was nonsignificant (P=0.37). Also, both treated groups had significant difference with the control group for RNB (P=0.015). There were no significant differences between the three groups for Ficat classification at the 6th week (P=0.65); EQ at 6th (P=0.59) and 12th week (P=0.64); and NBF (P=0.55). Conclusion: Although zoledronic acid therapy along with vitamin E could improve some radiologic and pathological indices related to femoral head osteonecrosis, vitamin E showed a relative impact. Level of evidence: I