Butler S L, Kohles S S, Thielke R J, Chen C, Vanderby R
University of Wisconsin-Milwaukee, Wisconsin.
Med Biol Eng Comput. 1997 Nov;35(6):742-6. doi: 10.1007/BF02510987.
The purpose of this study is to describe interstitial fluid flow in axisymmetric soft connective tissue (ligaments or tendons) when they are loaded in tension. Soft hydrated tissue was modelled as a porous medium (using Darcy's Law), and the finite element method was used to solve the resulting equations governing fluid flow. A commercially available computer program (FiDAP) was used to create an axisymmetric model of a biomechanically tested rat ligament. The unknown variables at element nodes were pressure and velocity of the interstitial fluid (Newtonian and incompressible). The effect of variations in fluid viscosity and permeability of the solid matrix was parametrically explored. A transient loading state mimicking a rat ligament mechanical experiment was used in all simulations. The magnitude and distribution of pressure, stream lines, shear (stress) rate, vorticity and velocity showed regular patterns consistent with extension flow. Parametric changes of permeability and viscosity strongly affected fluid flow behaviour. When the radial permeability was 1000 times less than the axial permeability, shear rate and vorticity increased (approximately 5-fold). These effects (especially shear stress and pressure) suggested a strong interaction with the solid matrix. Computed levels of fluid flow suggested a possible load transduction mechanism for cells in the tissue.
本研究的目的是描述轴对称软结缔组织（韧带或肌腱）在承受拉伸载荷时的组织液流动情况。将水合软组织建模为多孔介质（采用达西定律），并使用有限元方法求解由此产生的控制流体流动的方程。使用商业计算机程序（FiDAP）创建了一个经过生物力学测试的大鼠韧带的轴对称模型。单元节点处的未知变量是组织液的压力和速度（牛顿流体且不可压缩）。参数化地探究了流体粘度和固体基质渗透率变化的影响。在所有模拟中均使用了模拟大鼠韧带力学实验的瞬态加载状态。压力、流线、剪切（应力）率、涡度和速度的大小及分布呈现出与拉伸流动一致的规律模式。渗透率和粘度的参数变化强烈影响流体流动行为。当径向渗透率比轴向渗透率小1000倍时，剪切率和涡度增加（约5倍）。这些效应（尤其是剪切应力和压力）表明与固体基质存在强烈相互作用。计算得到的流体流动水平表明组织中的细胞可能存在一种载荷传递机制。
