Tissue viscoelasticity is related to tissue composition but may not fully predict the apparent-level viscoelasticity in human trabecular bone - An experimental and finite element study
Tissue viscoelasticity is related to tissue composition but may not fully predict the apparent-level viscoelasticity in human trabecular bone - An experimental and finite element study
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DOI：
10.1016/j.jbiomech.2017.10.002
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发表时间：
2017-12-08
影响因子：
2.4
通讯作者：
Toyras, J.
中科院分区：
文献类型：
--
作者：
Ojanen, X.;Tanska, P.;Toyras, J.
动态载荷下，松质骨是粘弹性的。然而，目前还不清楚组织粘弹性如何在表观水平上控制粘弹性。在这项研究中，粘弹性的圆柱形人骨小梁样本（n =11，男性，年龄18-78岁）从11个股骨近端的特点是使用动态和应力松弛测试在表观水平和蠕变纳米压痕在组织水平。此外，使用扫描声学显微镜（SAM）测定骨组织弹性。分别使用拉曼显微光谱和高效液相色谱法（HPLC）评估组织组成和胶原交联。材料参数的值从有限元（FE）模型通过优化组织水平的蠕变和表观水平的应力松弛实验纳米压痕和无侧限压缩测试值，分别获得，利用二阶Prony系列描绘粘弹性。FE模拟表明，组织水平的平衡弹性模量（E-eq）随着结晶度的增加而增加（r = 0.730，p = 0.011），而在表观水平上，它随着羟赖氨酰吡啶啉含量的增加而增加（r= 0.718，p = 0.019）。此外，归一化剪切模量g（7）（r = 0.780，p = 0.005）在组织水平上随着胶原比率（酰胺III/CH 2）的增加而降低，但在表观水平上随着胶原比率的增加而增加（r = 0.696，p = 0.025）。在组织和表观水平上测量或模拟的粘弹性参数之间没有显着的关系，也没有与SAM确定的组织弹性相关的参数。然而，只有g（2）和松弛时间r从模拟粘弹性值之间的组织和表观水平有统计学差异（p
Trabecular bone is viscoelastic under dynamic loading. However, it is unclear how tissue viscoelasticity controls viscoelasticity at the apparent-level. In this study, viscoelasticity of cylindrical human trabecular bone samples (n =11, male, age 18-78 years) from 11 proximal femurs were characterized using dynamic and stress-relaxation testing at the apparent-level and with creep nanoindentation at the tissue-level. In addition, bone tissue elasticity was determined using scanning acoustic microscope (SAM). Tissue composition and collagen crosslinks were assessed using Raman micro-spectroscopy and high performance liquid chromatography (HPLC), respectively. Values of material parameters were obtained from finite element (FE) models by optimizing tissue-level creep and apparent-level stress-relaxation to experimental nanoindentation and unconfined compression testing values, respectively, utilizing the second order Prony series to depict viscoelasticity. FE simulations showed that tissue-level equilibrium elastic modulus (E-eq) increased with increasing crystallinity (r = 0.730, p =.011) while at the apparent-level it increased with increasing hydroxylysyl pyridinoline content (r= 0.718, p =.019). In addition, the normalized shear modulus,g(7) (r = 0.780, p =.005) decreased with increasing collagen ratio (amide III/CH2) at the tissue level, but increased (r = 0.696, p =.025) with increasing collagen ratio at the apparent-level. No significant relations were found between the measured or simulated viscoelastic parameters at the tissue-and apparent-levels nor were the parameters related to tissue elasticity determined with SAM. However, only g(2) and relaxation time r from simulated viscoelastic values were statistically different between tissue-and apparent-levels (p