Hierarchies of damage induced loss of mechanical properties in calcified bone after in vivo fatigue loading of rat ulnae.

摘要: During fatigue loading of whole bone, damage to bone tissue accumulates, coalesces and leads fractures. Whether affects material properties similarly at the nanoscale (less than 1 μm), microscale mm), scale has not been fully evaluated. Therefore, in this study, we examine scale-dependent loss calcified rat ulnae, after forearms using forearm compression model. In vivo was conducted on right until a displacement end-point reached. The non-fatigued left served as contralateral controls. Subsequently, three-point bending tests failure excised ulnae demonstrated 41% 49% reduction stiffness ultimate strength compared control respectively. Depth-sensing microindentation an average decrease properties, such elastic modulus hardness, 28% 29% Nanoindentation measured hardness were reduced by 26% damaged relative controls, increased indentation is mainly attributed presence macrocrack located medial compressive region site peak strains. similar magnitude changes nanoindentation that may originate even smaller scale, inferred from 10% differences connectivity osteocyte canaliculi bone.