Ramo Nicole, Shetye Snehal S, Puttlitz Christian M
School of Biomedical Engineering, Colorado State University, 1376 Campus Delivery, Fort Collins, CO 80523-1376.
Department of Mechanical Engineering, Colorado State University, 1374 Campus Delivery, Fort Collins, CO 80523-1374.
J Eng Sci Med Diagn Ther. 2018 Feb;1(1):0110061-110068. doi: 10.1115/1.4038261. Epub 2017 Nov 21.
As the strongest of the meningeal tissues, the spinal dura mater plays an important role in the overall behavior of the spinal cord-meningeal complex (SCM). It follows that the accumulation of damage affects the dura mater's ability to protect the cord from excessive mechanical loads. Unfortunately, current computational investigations of spinal cord injury (SCI) etiology typically do not include postyield behavior. Therefore, a more detailed description of the material behavior of the spinal dura mater, including characterization of damage accumulation, is required to comprehensively study SCI. Continuum mechanics-based viscoelastic damage theories have been previously applied to other biological tissues; however, the current work is the first to report damage accumulation modeling in a tissue of the SCM complex. Longitudinal (i.e., cranial-to-caudal long-axis) samples of ovine cervical dura mater were tensioned-to-failure at one of three strain rates (quasi-static, 0.05/s, and 0.3/s). The resulting stress-strain data were fit to a hyperelastic continuum damage model to characterize the strain-rate-dependent subfailure and failure behavior. The results show that the damage behavior of the fibrous and matrix components of the dura mater are strain-rate dependent, with distinct behaviors when exposed to strain rates above that experienced during normal voluntary neck motion suggesting the possible existence of a protective mechanism.
作为脑膜组织中最强韧的部分，脊髓硬脊膜在脊髓 - 脑膜复合体（SCM）的整体行为中起着重要作用。由此可见，损伤的累积会影响硬脊膜保护脊髓免受过度机械负荷的能力。不幸的是，目前对脊髓损伤（SCI）病因的计算研究通常不包括屈服后行为。因此，为了全面研究脊髓损伤，需要对脊髓硬脊膜的材料行为进行更详细的描述，包括损伤累积的特征。基于连续介质力学的粘弹性损伤理论此前已应用于其他生物组织；然而，目前的工作是首次报道在SCM复合体组织中的损伤累积建模。对羊颈段硬脊膜的纵向（即头 - 尾长轴）样本在三种应变率（准静态、0.05/s和0.3/s）之一的条件下进行拉伸直至破坏。将得到的应力 - 应变数据拟合到一个超弹性连续损伤模型中，以表征应变率相关的亚破坏和破坏行为。结果表明，硬脊膜纤维和基质成分的损伤行为与应变率有关，当暴露于高于正常自主颈部运动时所经历的应变率时，会表现出不同的行为，这表明可能存在一种保护机制。
