Role of microstructure in the aging-related deterioration of the toughness of human cortical bone
Role of microstructure in the aging-related deterioration of the toughness of human cortical bone
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DOI：
10.1016/j.msec.2005.08.021
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发表时间：
2006-09-01
期刊：
影响因子：
--
通讯作者：
Ritchie, R. O.
中科院分区：
文献类型：
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作者：
Nalla, R. K.;Kruzic, J. J.;Ritchie, R. O.
随着年龄的增长，骨骼的骨折特性恶化，加上预期寿命的延长，是导致老年人骨折发生率增加的原因；因此，了解这些断裂特性如何随着年龄的增长而退化是至关重要的。在这项研究中，进行了离体骨折实验，以定量评估年龄对人类皮质骨近端和远端方向的影响，即沿骨纵向的影响。由于皮质骨表现出随着裂纹扩展而增加的抗裂纹增长能力，因此韧性是根据阻力曲线（r曲线）行为来评估的，测量了来自广泛年龄组（34-99岁）的骨骼。采用该方法测定了裂纹萌生韧度和裂纹扩展韧度，并发现裂纹萌生韧度随时效而降低；在40 ~ 100年的60年间，合金的起生韧性降低了约40%，而在相同的年龄范围内，合金的生长韧性被有效消除。裂纹扩展韧性的降低被认为主要与外部增韧程度的退化有关，特别是与裂纹发生后的裂纹桥接有关。使用光学显微镜、x射线断层扫描、纳米压痕和拉曼光谱对老化过程中伴随的微/纳米结构变化进行了检查，证明了这一观察结果。Elsevier B.V.出版
The aging-related deterioration of the fracture properties of bone, coupled with higher life expectancy, is responsible for increasing incidence of bone fracture in the elderly; consequently, an understanding of how these fracture properties degrade with age is essential. In this study, ex vivo fracture experiments have been performed to quantitatively assess the effect of age on human cortical bone in the proximaldistal orientation, i.e., longitudinally along the osteons. Because cortical bone exhibits rising crack-growth resistance with crack extension, the toughness is evaluated in terms of resistance-curve (R-curve) behavior, measured for bone taken from wide range of age groups (34-99 years). Using this approach, both the crack-initiation and crack-growth toughness are determined and are found to deteriorate with age; the initiation toughness decreases some 40% over six decades from 40 to 100 years, while the growth toughness is effectively eliminated over the same age range. The reduction in crack-growth toughness is considered to be associated primarily with a degradation in the degree of extrinsic toughening, in particular, involving crack bridging in the wake of the crack. An examination of the micro-/nano-structural changes accompanying the process of aging, using optical microscopy, X-ray tomography, nanoindentation and Raman spectroscopy, is shown to support such observations. Published by Elsevier B.V.