Mapping the depth dependence of shear properties in articular cartilage
Mapping the depth dependence of shear properties in articular cartilage
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DOI：
10.1016/j.jbiomech.2008.05.021
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发表时间：
2008-08-07
影响因子：
2.4
通讯作者：
Cohen, Itai
中科院分区：
文献类型：
--
作者：
Buckley, Mark R.;Gleghorn, Jason P.;Cohen, Itai
确定关节软骨剪切特性的深度依赖性对于理解该组织的结构-功能关系至关重要。在这里，我们使用一种结合剪切测试、共聚焦成像和力测量的新技术测量了牛关节软骨剪切模量G的空间变化。我们发现，G在单个样本中变化高达两个数量级，在表面区域下方的关节表面以下区域显示出全球最小值50-250 μ m，并且在深度bbb1000 μ m（“高原地区”）大致恒定。高原应变gamma（plateau）近似为0.75%，总压缩应变epsilon近似为5%，G（min）和G（plateau）分别近似为70和650k Pa。此外，我们发现剪切模量剖面强烈依赖于施加的剪切应变和轴向应变。G的最大变化发生在组织高度非线性的全局最小值处，在剪切应变增加下变硬，在压缩应变增加下变弱。我们的结果可以通过一个简单的思维模型来解释，该模型描述了观察到的胶原纤维局部屈曲的非线性行为，并表明压缩可以通过降低单个胶原纤维的有效应变来降低关节软骨对剪切引起的损伤的脆弱性。(c) 2008 Elsevier Ltd.版权所有。
Determining the depth dependence of the shear properties of articular cartilage is essential for understanding the structure-function relation in this tissue. Here, we measured spatial variations in the shear modulus G of bovine articular cartilage using a novel technique that combines shear testing, confocal imaging and force measurement. We found that G varied by up to two orders of magnitude across a single sample, exhibited a global minimum 50-250 mu m below the articular surface in a region just below the superficial zone and was roughly constant at depths > 1000 mu m (the "plateau region"). For plateau strains gamma(plateau)approximate to 0.75% and overall compressive strains epsilon approximate to 5%, G(min) and G(plateau) were approximate to 70 and approximate to 650k Pa, respectively. In addition, we found that the shear modulus profile depended strongly on the applied shear and axial strains. The greatest change in G occurred at the global minimum where the tissue was highly nonlinear, stiffening under increased shear strain, and weakening under increased compressive strain. Our results can be explained through a simple thought model describing the observed nonlinear behavior in terms of localized buckling of collagen fibers and suggest that compression may decrease the vulnerability of articular cartilage to shear-induced damage by lowering the effective strain on individual collagen fibrils. (c) 2008 Elsevier Ltd. All rights reserved.