Department of Orthopaedic Surgery, University Hospitals Case Medical Center, Cleveland, OH, US.
J Biomech. 2011 Jul 7;44(10):1995-8. doi: 10.1016/j.jbiomech.2011.04.039. Epub 2011 May 18.
Cortical bone specimens were damaged using repeated blocks of tensile creep loading until a near-terminal amount of creep damage was generated (corresponding to a reduction in elastic modulus of 15%). One group of cortical bone specimens was submitted to the near-terminal damage protocol and subsequently underwent fatigue loading in tension with a maximum strain of 2000 με (Damage Fatigue, n=5). A second group was submitted to cyclic fatigue loading but was not pre-damaged (Control Fatigue, n=5). All but one specimen (a damaged specimen) reached run-out (10 million cycles, 7.7 days). No significant differences in microscopic cracks or other tissue damage were observed between the two groups or between either group and additional, completely unloaded specimens. Our results suggest that damage in cortical bone allograft that is not obvious or associated with a stress riser may not substantially affect its fatigue life under physiologic loading.
皮质骨标本经过反复的拉伸蠕变加载，直至产生接近终末的蠕变损伤（对应弹性模量降低 15%）。一组皮质骨标本采用接近终末损伤方案，随后进行最大应变为 2000 με 的拉伸疲劳加载（损伤疲劳，n=5）。第二组进行循环疲劳加载，但未预先损伤（对照疲劳，n=5）。除一个标本（损伤标本）外，所有标本均达到运行结束（1000 万次循环，7.7 天）。两组之间或任何一组与完全卸载的额外标本之间，均未观察到微观裂纹或其他组织损伤的显著差异。我们的结果表明，皮质骨同种异体移植物中的损伤如果不明显或不与应力集中器相关，则在生理负荷下可能不会显著影响其疲劳寿命。
