Determining the biomechanical quality of normal and osteoporotic bones in rat femora through biomechanical test and finite element analysis

Objectives: This study aimed to determine the biome¬chanical quality of cortical bone in normal and osteo- porotic rat femora with the use of biomechanical analy¬sis and finite element analysis. Methods: Fourteen young adult female Sprague-Dawley rats weighing 225-250 g were randomized into two groups equal in number. One group underwent bilateral ovariecto- my under ketamine anesthesia. Fourteen weeks after ovariectomy, bone mineral density was measured by dual energy X-ray absorptiometry in two groups and the rats were sacrificed under high-dose ketamine anesthesia for removal of all the femora. The right femora were subjected to biomechanical tension tests. In the left femora, cortical bone sections were visualized by computed tomography and finite element analysis was performed on computer- gener¬ated three dimensional images using the ANYSIS 9.0 soft¬ware. Deformation, stress, and strain values obtained by the two analyses were compared. Results: Compared to the control group, bone mineral density decreased by 29%, and decreases in deformation, stress, and strain values were 39%, 51%, and 64%, respec¬tively, in the ovariectomized rats (p<0.05). No significant differences were found between the results of b i o m e c h a n- ical measurements and finite element analysis (p>0.05). Conclusion: Our data suggest that finite element analysis can be used in vivo to determine biomechanical quality of the bone in osteoporotic patients.