Development of residual strains in human vertebral trabecular bone after prolonged static and cyclic loading at low load levels
Development of residual strains in human vertebral trabecular bone after prolonged static and cyclic loading at low load levels
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DOI：
10.1016/j.jbiomech.2005.05.017
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发表时间：
2006-01-01
影响因子：
2.4
通讯作者：
Keaveny, Tony M.
中科院分区：
文献类型：
--
作者：
Yamamoto, Ei;Crawford, R. Paul;Keaveny, Tony M.
骨小梁中不可逆残余应变的发展可能是年龄相关性非创伤性椎体骨折发生的机制。为了研究这一概念，在低载荷水平下对尸体椎体松质骨的圆柱形核心进行静态和循环载荷测试。施加的应力相当于750或1500微应变的弹性应变。在测试期间测量蠕变应变，该测试持续125，000秒（约35小时），并且在完全卸载后再持续125，000秒。重点放在残余应变的发展，定义为在卸载阶段结束时剩余的应变。结果表明，相当大的残余应变确实发展，并为静态和循环加载相似。无论施加的载荷水平和加载模式如何，卸载阶段后剩余的残余应变在大小上与最初施加的弹性应变相似。将观察到的残余应变外推到完全恢复表明，完全恢复所需的时间比施加载荷的持续时间长20倍以上。这些结果表明，人体脊椎骨小梁在低应力水平下不会以线性粘弹性方式蠕变，并且无论加载模式如何，蠕变机制都主导残余应变。总之，这些发现支持了非创伤性椎骨骨折可能与长期蠕变效应相关的概念，因为骨小梁没有足够的时间从长期静态或循环载荷累积的蠕变变形中机械恢复。(c)2005爱思唯尔有限公司保留所有权利。
Development of irreversible residual strains in trabecular bone may be a mechanism by which age-related non-traumatic vertebral fractures occur. To investigate this concept, static and cyclic loading tests were conducted at low loading levels for cylindrical cores of cadaveric vertebral trabecular bone. Stresses were applied equivalent to elastic strains of either 750 or 1500 microstrain. Creep strains were measured during the tests, which lasted for 125,000 seconds (about 35 h), and for an additional 125,000 seconds after complete unloading. Emphasis was placed on the residual strains that developed, defined as the strain remaining at the end of the unloading phase. The results indicated that appreciable residual strains did develop, and were similar for static and cyclic loading. Irrespective of the applied load levels and loading modes, the residual strains that remained after the unloading phase were similar in magnitude to the originally applied elastic strain. Extrapolation of the observed residual strains to full recovery indicated that the time that would be required for full recovery was over 20 times longer than the duration of the applied loads. These results indicate that human vertebral trabecular bone does not creep in a linear viscoelastic fashion at low stress levels, and that creep mechanisms dominate the residual strains regardless of the loading mode. Taken together, these findings support the concept that non-traumatic vertebral fractures may be related to long-term creep effects because the trabecular bone does not have sufficient time to recover mechanically from creep deformations accumulated by prolonged static or cyclic loading. (c) 2005 Elsevier Ltd. All rights reserved.