Kazemi M, Li L P
Department of Mechanical and Manufacturing Engineering, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta, Canada T2N 1N4.
Department of Mechanical and Manufacturing Engineering, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta, Canada T2N 1N4.
Med Eng Phys. 2014 Aug;36(8):998-1006. doi: 10.1016/j.medengphy.2014.04.004. Epub 2014 Jun 2.
The elastic response of the knee joint in various loading and pathological conditions has been investigated using anatomically accurate geometry. However, it is still challenging to predict the poromechanical response of the knee in realistic loading conditions. In the present study, a viscoelastic, poromechanical model of the knee joint was developed for soft tissues undergoing large deformation. Cartilages and menisci were modeled as fibril-reinforced porous materials and ligaments were considered as fibril-reinforced hyperelastic solids. Quasi-linear viscoelasticty was formulated for the collagen network of these tissues and nearly incompressible Neo-Hookean hyperelasticity was used for the non-fibrillar matrix. The constitutive model was coded with a user defined FORTRAN subroutine, in order to use ABAQUS for the finite element analysis. Creep and stress relaxation were investigated with large compression of the knee in full extension. The contact pressure distributions were found similar in creep and stress relaxation. However, the load transfer in the joint was completely different in these two loading scenarios. During creep, the contact pressure between cartilages decreased but the pressure between cartilage and meniscus increased with time. This led to a gradual transfer of some loading from the central part of cartilages to menisci. During stress relaxation, however, both contact pressures decreased monotonically.
利用解剖学精确的几何形状，研究了膝关节在各种加载和病理条件下的弹性响应。然而，在实际加载条件下预测膝关节的孔隙力学响应仍然具有挑战性。在本研究中，针对经历大变形的软组织，开发了一种膝关节的粘弹性孔隙力学模型。软骨和半月板被建模为纤维增强多孔材料，韧带被视为纤维增强超弹性固体。针对这些组织的胶原网络制定了准线性粘弹性，并对非纤维状基质使用了近不可压缩的新胡克超弹性。本构模型用用户定义的FORTRAN子程序编码，以便使用ABAQUS进行有限元分析。通过在完全伸展状态下对膝关节进行大压缩来研究蠕变和应力松弛。发现蠕变和应力松弛中的接触压力分布相似。然而，在这两种加载情况下，关节中的载荷传递完全不同。在蠕变过程中，软骨之间的接触压力降低，但软骨与半月板之间的压力随时间增加。这导致一些载荷从软骨中心部分逐渐转移到半月板。然而，在应力松弛过程中，两种接触压力均单调下降。
