Estimation of material properties in the equine metacarpus with use of quantitative computed tomography

The purpose of this study was to investigate the relationships between data obtained from quantitative computed tomography and mechanical properties in the equine metacarpus, as measured in vitro in bone specimens. Three hundred and fifty-five bone specimens from the metacarpi of 10 horses were machined into right cylinders aligned with the long axis of the bone. A computed tomographic scan of the specimens, along with a Cann-Genant K₂HPO₄ calibration standard, was obtained. The specimens then were compressed to failure, and the elastic modulus, yield stress, yield strain, strain energy density at yield, ultimate stress, ultimate strain, and strain energy density at ultimate failure were calculated. The specimens were dried and ashed. Quantitative computed tomography-derived K₂HPO₄ equivalent density proved to be an excellent estimator (r² > 0.9) of elastic modulus, yield stress, ultimate stress, wet density, dry density, and ash density; a moderately good estimator (0.4 < r² < 0.9) of strain energy density at yield and at ultimate failure; and a poor estimator (r² < 0.2) of yield strain and ultimate strain. It was concluded that the relationships between quantitative computed tomography data and mechanical properties of the equine metacarpus were strong enough to justify the use of these data in automated finite element modeling.