Measurement of soft tissue elasticity in vitro-common methods and applications

Abstract

弹性是软组织一个很重要的力学参数, 可用于生物力学系统的建模、分析和病灶的诊断及治疗手段有效性的评估。根据弹性力学和材料力学基本知识,可用标准测试例如压缩、拉伸、扭转和弯曲等来测量 组织的弹性特征。这些测试的优点是边界条件简单,很容易直接获得组织的本征弹性参数例如杨氏模量、剪切模量或者泊松比。但是因为测试需要准备形状规则的样 本,所以这些方法仅适用于离体组织的测量。结合适当的粘弹性模型,这些标准测试还可以用于测试组织的非线性粘弹性参数。因为可以方便测得组织很重要的基本 弹性特征,这些离体组织样本测试方法还是被大量用于实际测量当中。这期我们将对离体组织样本的常用弹性测量方法作一些介绍,并分析这些测量方法及相关力学 模型的优点和缺点,最后以软骨的离体样本测试为例说明这些弹性测试方法在生物医学相关领域的应用。 Elasticity is an important characteristic of soft tissue which can be used for establishment of tissue mechanical model,simulation and analysis of biomechanical systems,diagnosis of diseases,and evaluation of new treatment efficacy.From the fundamental knowledge of elastic mechanics and material mechanics,the elasticity of soft tissue can be measured using standard testing methods such as compression,tension,torsion and bending.The advantages of these tests are simple boundary conditions so that intrinsic elastic properties such as Young’s modulus,shear modulus or Poisson’s ratio can be easily measured.However,because of the requirement of preparation of samples with a regular shape,these tests can be only applied for soft tissue assessment in vitro.With the incorporation of viscoelastic models,these tests can also be used to measure the nonlinear elastic and viscous parameters of soft tissues.Because of easy operation,these tests have been widely used to measure the elastic properties of soft tissues in practice.In this paper,we introduce some common techniques for the measurement of soft tissues elasticity in vitro and discuss the advantages and disadvantages of these techniques and corresponding biomechanical models.Finally we use the mechanical test of articular cartilage in vitro as an example to explain the applications of these methods in fields of biomedical engineering.