Geometric variables and bone mineral density as potential predictors for mechanical properties of the radius of Greyhounds

Abstract

Abstract Objective To determine cross-sectional geometry and bone mineral density of the Greyhound radius and correlate these values with torsional failure load and torsional stiffness in an ex vivo model. Design 3 regions, proximal, middle, and distal portions of the diaphysis, were studied. 5 levels of cross section were evaluated geometrically within each region. Specimens 10 paired radiuses from skeletally mature Greyhounds. Procedure Cortical area and area moment of inertia were measured from plain radiographic views and from digitized computed tomographic images. Bone mineral density was measured, using dual-energy x-ray absorptiometry. Torsional stiffness and torsional failure load were then determined mechanically. Results Minimum area moment of inertia and area moment of inertia estimated from plain radiographic views were significantly different in different regions of interest (P < 0.05). Significant bivariate correlations (P < 0.05) between torsional mechanical parameters and bone properties of the radius were identified for the distal portion of the diaphysis in particular. When independent variables for the distal portion were analyzed, estimate of area moment of inertia was entered into the model for torsional failure load as a predictor and minimum area moment of inertia was entered into the model for torsional stiffness as a predictor. Bone mineral density of the distal portion of the diaphysis was not a significant predictor. Conclusion If accurate noninvasive predictors of bone failure load can be identified, further study of fracture risk should be possible. (Am J Vet Res 1996;57:1094–1097)