Mechanical & Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Canada.
Mechanical & Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Canada.
J Mech Behav Biomed Mater. 2024 Mar;151:106412. doi: 10.1016/j.jmbbm.2024.106412. Epub 2024 Jan 18.
Spinal cord injuries (SCIs) can arise from compression loading when a vertebra fractures and bone fragments are pushed into the spinal canal. Experimental studies have demonstrated the importance of both fracture initiation and post-fracture response in the investigation of vertebral fractures and spinal canal occlusion resulting from compression. Finite element models, such as the Global Human Body Models Consortium (GHBMC) model, focused on predicting the initiation location of fractures using element erosion to model hard tissue fracture. However, the element erosion method resulted in a loss of material and structural support during compression, which limited the ability of the model to predict the post-fracture response. The current study aimed to improve the post-fracture response by combining strain-based element erosion with smoothed particle hydrodynamics (SPH) to preserve the volume of the trabecular bone during compression fracture. The proposed implementation was evaluated using a model comprising two functional spinal units (FSUs) (C5-C6-C7) extracted from the GHBMC 50th percentile male model, and loaded under central compression. The original and enhanced models were compared to experimental force-displacement data and measured occlusion of the spinal canal. The enhanced model with SPH improved the shape and magnitude of the force-displacement response to be in good agreement with the experimental data. In contrast to the original model, the enhanced SPH model demonstrated occlusion on the same order of magnitude as reported in the experiments. The SPH implementation improved the post-fracture response by representing the damaged material post-fracture, providing structural support throughout compression loading and material flow leading to occlusion.
脊髓损伤 (SCI) 可由椎骨骨折和骨碎片推入椎管时的压缩载荷引起。实验研究表明，在研究由于压缩导致的椎体骨折和椎管闭塞时，骨折的起始和骨折后的反应都很重要。有限元模型，如全球人体模型联合会 (GHBMC) 模型，专注于使用单元侵蚀来模拟硬组织骨折，从而预测骨折的起始位置。然而，单元侵蚀方法在压缩过程中导致材料和结构支撑的损失，这限制了模型预测骨折后反应的能力。本研究旨在通过将基于应变的单元侵蚀与平滑粒子流体动力学 (SPH) 相结合，在压缩骨折过程中保持小梁骨的体积，从而改善骨折后的反应。使用从 GHBMC 第 50 百分位数男性模型中提取的两个功能脊柱单元 (FSU) (C5-C6-C7) 组成的模型评估了所提出的实现方案，并在中央压缩下进行了加载。将原始模型和增强模型与实验力-位移数据和测量的椎管闭塞进行了比较。具有 SPH 的增强模型改善了力-位移响应的形状和幅度，使其与实验数据非常吻合。与原始模型相比，增强的 SPH 模型表现出与实验中报告的相同量级的闭塞。SPH 的实现通过代表骨折后的受损材料，在整个压缩加载过程中提供结构支撑以及导致闭塞的材料流动，从而改善了骨折后的反应。
