Orthopaedic and Injury Biomechanics Group, Departments of Mechanical Engineering and Orthopaedics, The School of Biomedical Engineering and International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Neuroscience Research Australia, Margarete Ainsworth Building, Barker Street, Randwick, NSW 2031, Australia.
Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue W, Waterloo, ON N2 L 3G1, Canada.
J Biomech Eng. 2021 Jun 1;143(6). doi: 10.1115/1.4050030.
The cervical spine experiences shear forces during everyday activities and injurious events yet there is a paucity of biomechanical data characterizing the cervical spine under shear loading. This study aimed to (1) characterize load transmission paths and kinematics of the subaxial cervical spine under shear loading, and (2) assess a contemporary finite element cervical spine model using this data. Subaxial functional spinal units (FSUs) were subjected to anterior, posterior, and lateral shear forces (200 N) applied with and without superimposed axial compression preload (200 N) while monitoring spine kinematics. Load transmission paths were identified using strain gauges on the anterior vertebral body and lateral masses and a disc pressure sensor. Experimental conditions were simulated with cervical spine finite element model FSUs (GHBMC M50 version 5.0). The mean kinematics, vertebral strains, and disc pressures were compared to experimental results. The shear force-displacement response typically demonstrated a toe region followed by a linear response, with higher stiffness in anterior shear relative to lateral and posterior shear. Compressive axial preload decreased posterior and lateral shear stiffness and increased initial anterior shear stiffness. Load transmission patterns and kinematics suggest the facet joints play a key role in limiting anterior shear while the disc governs motion in posterior shear. The main cervical spine shear responses and trends are faithfully predicted by the GHBMC cervical spine model. These basic cervical spine biomechanics and the computational model can provide insight into mechanisms for facet dislocation in high severity impacts, and tissue distraction in low severity impacts.
颈椎在日常活动和损伤事件中会受到剪切力，但关于颈椎在剪切载荷下的生物力学数据却很少。本研究旨在：(1)描述亚下颈椎在剪切载荷下的载荷传递路径和运动学；(2)使用这些数据评估当代有限元颈椎模型。在下颈椎功能单位 (FSUs) 上施加前向、后向和侧向剪切力 (200N)，同时施加和不施加附加轴向压缩预载 (200N)，监测脊柱运动学。使用前椎体和侧块上的应变计以及椎间盘压力传感器来确定载荷传递路径。使用颈椎有限元模型 FSUs (GHBMC M50 版本 5.0) 模拟实验条件。将平均运动学、椎体应变和椎间盘压力与实验结果进行比较。剪切力-位移响应通常表现为一个初始阶段，随后是线性响应，前向剪切的刚度高于侧向和后向剪切。轴向压缩预载降低了后向和侧向剪切刚度，增加了初始前向剪切刚度。载荷传递模式和运动学表明，关节突关节在限制前向剪切方面起着关键作用，而椎间盘在控制后向剪切运动方面起着主导作用。GHBMC 颈椎模型忠实地预测了主要的颈椎剪切响应和趋势。这些基本的颈椎生物力学和计算模型可以为高严重度冲击中的关节突脱位机制以及低严重度冲击中的组织分离提供深入的了解。
