Bone mineral density and computer tomographic measurements in correlation with failure strength of equine metacarpal bones

Abstract

Information regarding bone mineral density and fracture characteristics of the equine metacarpus are lacking. The aim of this study was to characterize the relationship between mechanical properties of the equine metacarpal bone and its biomechanical and morphometric properties. Third metacarpal bones were extracted from horses euthanized unrelated to musculoskeletal conditions. In total, bone specimens from 26 front limbs of 13 horses (7.8 ± 5.8 years old) including Lipizzaner (n = 5), Hungarian Warmblood (n = 2), Holsteiner (n = 2), Thoroughbred (n = 1), Hungarian Sporthorse (n = 1), Friesian (n = 1), and Shagya Arabian (n = 1) were collected. The horses included 7 mares, 4 stallions and 2 geldings. Assessment of the bone mineral density of the whole bone across four specific regions of interest was performed using dual-energy X-ray absorptiometry. The bones were scanned using a computer tomographic scanner to measure cross-sectional morphometric properties such as bone mineral density and cross-sectional dimensions including cortical area and cortical width. Mechanical properties (breaking force, bending strength, elastic modulus) were determined by a 3-point bending test. Significant positive linear correlations were found between the breaking force and bone mineral density of the entire third metacarpal bones (P < 0.001, r = 0.72), the medial cortex region of interest (P < 0.001, r = 0.68) and the transverse region of interest (P < 0.001, r = 0.61). The correlation between the breaking force and bone mineral density of the equine third metacarpal bone found in this study warrants in vivo investigations.