Abstract
Introduction
Bisphosphonates are among the most commonly prescribed drugs in Osteoporotic Patients. Their mode of action is anti-resorptive. Since remodeling is a key step in fracture healing, there has been concern regarding the effect of bisphosphonates on fracture healing.
Objectives
To assess the effect of alendronate on fracture healing in the rabbit ulna osteotomy model.
Materials and methods
16 New Zealand white rabbits were divided into 2 equal groups. Bilateral ulnar osteotomies were performed in the first week. Group 1 was the control group and group 2 was gavaged with alendronate solution (human equivalent dose). 2 rabbits were euthanised at 3 and 6 weeks and the remaining 4 rabbits were euthanised at 8 weeks.
Fracture healing was assessed radiologically, with mechanical testing using the Instron 4302 materials testing machine and histologically, in that order.
Results
The fractures healed satisfactorily in all the control group animals. However, in the alendronate treated group, there was an abundance of woven bone and little lamellar bone in the callus. However there was no significant difference in mechanical testing. In addition we did not find any evidence of Osteonecrosis in the Bisphosphonate treated group.
Conclusion
Bone remodelling in the alendronate treated group is slower but a larger amount of bone callus is formed around the fracture, thus giving the fracture callus a higher ultimate load to failure at an earlier stage.
