title: Stiff and strong compressive properties are associated with brittle post-yield behavior in equine compact bone material.
abstract: Our hypothesis was that post-yield mechanical behavior of compact bone material in compression, defined as the stress, strain, or energy absorbed between 0.2% strain-offset and the point of maximum stress, is correlated with material density, modulus, strength, histomorphometric evidence of remodeling, and post-failure gross specimen morphology. Post-yield behavior of compact bone material from the third metacarpal bone of 10 horses, ages 5 months to 20 years, was investigated using single-load compression-to-failure. The post-yield stress, strain, and absorbed energy were compared with the compressive elastic modulus, yield stress, ash density. post-failure macroscopic appearance of the specimen, and histologic evidence of remodeling. High values of elastic modulus, yield stress, and ash density were associated with low values of post-yield mechanical properties (stress, strain, and absorbed energy). Macroscopic post-failure morphology was associated with post-yield mechanical behavior, in that specimens displaying fractures were associated with lower post-yield mechanical properties, and that those without evidence of frank fracture were associated with higher post-yield mechanical properties. Microscopic evidence of remodeling activity was associated with high post-yield mechanical properties, but not with gross post-failure morphology. There was an abrupt change from relatively high values to extremely low values of post-yield mechanical properties at intermediate levels of ash density. This feature may serve as a functional tipper limit to the maximization of bone material stiffness and strength.
authors.affiliation: Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis 95616-8732, USA. les@bjc.hfh.edu
authors.forename: C M
authors.initials: CM
authors.lastname: Les
authors.forename: S M
authors.initials: SM
authors.lastname: Stover
authors.forename: J H
authors.initials: JH
authors.lastname: Keyak
authors.forename: K T
authors.initials: KT
authors.lastname: Taylor
authors.forename: A J
authors.initials: AJ
authors.lastname: Kaneps
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density; D016723:Bone Remodeling; D019245:Compressive Strength; D004548:Elasticity; D050723:Fractures, Bone / Q000503:physiopathology; D006736:Horses; D008663:Metacarpus / Q000293:injuries / Q000473:pathology / Q000502:physiology* / Q000503:physiopathology; D008903:Minerals / Q000378:metabolism; D013314:Stress, Mechanical
chemical_list: D008903:Minerals; C028705:bone ash