Keenan Kathryn E, Pal Saikat, Lindsey Derek P, Besier Thor F, Beaupre Gary S
Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
J Appl Biomech. 2013 Jun;29(3):292-302. doi: 10.1123/jab.29.3.292. Epub 2012 Oct 1.
Cartilage material properties provide important insights into joint health, and cartilage material models are used in whole-joint finite element models. Although the biphasic model representing experimental creep indentation tests is commonly used to characterize cartilage, cartilage short-term response to loading is generally not characterized using the biphasic model. The purpose of this study was to determine the short-term and equilibrium material properties of human patella cartilage using a viscoelastic model representation of creep indentation tests. We performed 24 experimental creep indentation tests from 14 human patellar specimens ranging in age from 20 to 90 years (median age 61 years). We used a finite element model to reproduce the experimental tests and determined cartilage material properties from viscoelastic and biphasic representations of cartilage. The viscoelastic model consistently provided excellent representation of the short-term and equilibrium creep displacements. We determined initial elastic modulus, equilibrium elastic modulus, and equilibrium Poisson's ratio using the viscoelastic model. The viscoelastic model can represent the short-term and equilibrium response of cartilage and may easily be implemented in whole-joint finite element models.
软骨材料特性为关节健康提供了重要见解，软骨材料模型被用于全关节有限元模型中。尽管代表实验性蠕变压痕试验的双相模型常用于表征软骨，但软骨对负荷的短期反应通常不用双相模型来表征。本研究的目的是使用蠕变压痕试验的粘弹性模型表示法来确定人髌骨软骨的短期和平衡材料特性。我们对14个年龄在20至90岁（中位年龄61岁）的人髌骨标本进行了24次实验性蠕变压痕试验。我们使用有限元模型来重现实验测试，并从软骨的粘弹性和双相表示法中确定软骨材料特性。粘弹性模型始终能很好地表示短期和平衡蠕变位移。我们使用粘弹性模型确定了初始弹性模量、平衡弹性模量和平衡泊松比。粘弹性模型可以表示软骨的短期和平衡反应，并且可以很容易地应用于全关节有限元模型中。
