Relationship between bone strength and dual-energy X-ray absorptiometry measurements in pigs

Computed tomography and a 3-point bending test were performed on the metacarpal bones of adult production pigs to test the hypothesis that bone strength is strongly correlated with areal bone mineral density (BMD) in this population. The aim of the study was to subject material from adult production pigs grouped by BMD to 3-point bending, to test this hypothesis and determine any correlations. In all, 168 individual computed tomography scans and mechanical tests were performed on the collected material. For evaluation purposes, the material was divided into the categories low, medium, and high BMD (<1, 1 to 1.4, and >1.4 g/cm(2), respectively). The results showed a difference in the maximum load, in the stress at maximum load, and stiffness among each BMD group (P < 0.001) and in elastic modulus between the low BMD group and the 2 other groups (P < 0.001). A correlation between both intrinsic and extrinsic measures of bone strength and BMD was thus demonstrated. The projected change in each of the variables reported, for a 0.1 g/cm(2) alteration in BMD (within the BMD range evaluated in this study), is as follows: maximum load, 708 N; stress at maximum load, 50 N/mm(2); stiffness, 391.6 N/mm; and elastic modulus, 108 N/mm(2) (P < 0.001). The results confirm the relationship between BMD and bone strength and indicate that BMD screening can be used in fracture risk assessments in production pigs.