Abstract：
This study addresses three primary objectives related to lumbar intervertebral disc (IVD) biomechanics under ramping quasi-static loading conditions. First, we explore the conditions justifying the simplification of axisymmetric elastic fiber families into single fiber bundles through discretized strain energy functions. Simulations reveal that a concentration factor exceeding 10 allows for a consistent deviation below 10% between simplified and non-simplified responses. Second, we investigate the impact of elastic fibers on the physiological stiffness in IVDs, revealing minimal influence on biological motions but significant effects on degeneration. Lastly, we examine the initiation and progression of annulus fibrosus (AF) damage. Our findings confirm the validity of simplifying elastic fiber families and underscore the necessity of considering elastic fiber damage in biomechanical studies of AF tissues. Elastic fibers contribute to increased biaxial stretch stiffness, and their damage significantly affects the loading capacity of the inner AF. Additionally, degeneration significantly alters the susceptibility to damage in the AF, with specific regions exhibiting higher vulnerability. Damage tends to extend circumferentially and radially, emphasizing the regional variations in collagen and elastic fiber properties. This study offers useful insights for refining biomechanical models, paving the way for a more comprehensive understanding of IVD responses and potential clinical implications.
摘要：
这项研究解决了在倾斜准静态载荷条件下与腰椎间盘（IVD）生物力学相关的三个主要目标。首先,我们通过离散的应变能函数探索了将轴对称弹性纤维族简化为单纤维束的条件。模拟表明，超过10的集中系数允许简化和非简化响应之间的一致偏差低于10％。第二,我们研究了弹性纤维对IVD生理刚度的影响，对生物运动的影响最小，但对退化的影响显著。最后,我们检查了纤维环（AF）损伤的发生和进展。我们的发现证实了简化弹性纤维家族的有效性，并强调了在AF组织的生物力学研究中考虑弹性纤维损伤的必要性。弹性纤维有助于增加双轴拉伸刚度，并且它们的损伤显著影响内部AF的负载能力。此外,变性显著改变了AF对损伤的敏感性，特定地区表现出更高的脆弱性。损伤倾向于沿圆周和径向延伸,强调胶原蛋白和弹性纤维特性的区域差异。这项研究为完善生物力学模型提供了有用的见解，为更全面地了解IVD反应和潜在的临床意义铺平了道路。
