Magnier Carole, Boiron Olivier, Wendling-Mansuy Sylvie, Chabrand Patrick, Deplano Valérie
Institute of Movement Sciences CNRS UMR 6233, Interdisciplinary Group of Osteoarticular Biomechanics, Aix-Marseilles University, Marseilles, France.
J Biomech. 2009 Jan 19;42(2):100-8. doi: 10.1016/j.jbiomech.2008.10.034. Epub 2008 Dec 24.
A 2-D finite element model for the intervertebral disc in which quadriphasic theory is coupled to the transport of solutes involved in cellular nutrition was developed for investigating the main factors contributing to disc degeneration. Degeneration is generally considered to result from chronic disc cell nutrition insufficiency, which prevents the cells from renewing the extracellular matrix and thus leads to the loss of proteoglycans. Hence, the osmotic power of the disc is decreased, causing osmomechanical impairments. Cellular metabolism depends strongly on the oxygen, lactate and glucose concentrations and on pH in the disc. To study the diffusion of these solutes in a mechanically or osmotically loaded disc, the osmomechanical and diffusive effects have to be coupled. The intervertebral disc is modeled here using a plane strain formulation at the equilibrium state under physiological conditions after a long rest period (called unloaded state). The correlations between solute distribution and various properties of healthy and degenerated discs are investigated. The numerical simulation shows that solute distribution in the disc depends very little on the elastic modulus or the proteoglycan concentration but greatly on the porosity, diffusion coefficient and endplate diffusion area. This coupled model therefore opens new perspectives for investigating intervertebral disc degeneration mechanisms.
为了研究导致椎间盘退变的主要因素，建立了一个二维椎间盘有限元模型，该模型将四相理论与细胞营养中溶质的运输相结合。退变通常被认为是由慢性椎间盘细胞营养不足引起的，这会阻止细胞更新细胞外基质，从而导致蛋白聚糖的流失。因此，椎间盘的渗透力降低，导致渗透力学损伤。细胞代谢在很大程度上取决于椎间盘中的氧气、乳酸和葡萄糖浓度以及pH值。为了研究这些溶质在机械或渗透压加载的椎间盘中的扩散，必须将渗透力学和扩散效应耦合起来。在此，使用平面应变公式对长时间休息后处于生理条件下平衡状态的椎间盘进行建模（称为未加载状态）。研究了溶质分布与健康和退变椎间盘各种特性之间的相关性。数值模拟表明，椎间盘中的溶质分布对弹性模量或蛋白聚糖浓度的依赖性很小，但对孔隙率、扩散系数和终板扩散面积的依赖性很大。因此，这个耦合模型为研究椎间盘退变机制开辟了新的视角。
