Wilcox R K, Allen D J, Hall R M, Limb D, Barton D C, Dickson R A
School of Mechanical Engineering, University of Leeds, LS2 9JT Leeds, UK.
Eur Spine J. 2004 Oct;13(6):481-8. doi: 10.1007/s00586-003-0625-9. Epub 2004 Jan 9.
Spinal burst fractures account for about 15% of spinal injuries and, because of their predominance in the younger population, there are large associated social and healthcare costs. Although several experimental studies have investigated the burst fracture process, little work has been undertaken using computational methods. The aim of this study was to develop a finite element model of the fracture process and, in combination with experimental data, gain a better understanding of the fracture event and mechanism of injury. Experimental tests were undertaken to simulate the burst fracture process in a bovine spine model. After impact, each specimen was dissected and the severity of fracture assessed. Two of the specimens tested at the highest impact rate were also dynamically filmed during the impact. A finite element model, based on CT data of an experimental specimen, was constructed and appropriate high strain rate material properties assigned to each component. Dynamic validation was undertaken by comparison with high-speed video data of an experimental impact. The model was used to determine the mechanism of fracture and the postfracture impact of the bony fragment onto the spinal cord. The dissection of the experimental specimens showed burst fractures of increasing severity with increasing impact energy. The finite element model demonstrated that a high tensile strain region was generated in the posterior of the vertebral body due to the interaction of the articular processes. The region of highest strain corresponded well with the experimental specimens. A second simulation was used to analyse the fragment projection into the spinal canal following fracture. The results showed that the posterior longitudinal ligament became stretched and at higher energies the spinal cord and the dura mater were compressed by the fragment. These structures deformed to a maximum level before forcing the fragment back towards the vertebral body. The final position of the fragment did not therefore represent the maximum dynamic canal occlusion.
脊柱爆裂骨折约占脊柱损伤的15%，由于其在年轻人群中较为常见，因此会产生巨大的社会和医疗成本。尽管有几项实验研究对爆裂骨折过程进行了调查，但使用计算方法开展的工作却很少。本研究的目的是建立骨折过程的有限元模型，并结合实验数据，更好地了解骨折事件和损伤机制。进行了实验测试以模拟牛脊柱模型中的爆裂骨折过程。撞击后，对每个标本进行解剖并评估骨折的严重程度。在最高撞击速率下测试的两个标本在撞击过程中也进行了动态拍摄。基于一个实验标本的CT数据构建了有限元模型，并为每个组件分配了合适的高应变率材料属性。通过与实验撞击的高速视频数据进行比较来进行动态验证。该模型用于确定骨折机制以及骨折后骨碎片对脊髓的撞击。实验标本的解剖显示，随着撞击能量的增加，爆裂骨折的严重程度也在增加。有限元模型表明，由于关节突的相互作用，在椎体后部产生了一个高拉伸应变区域。最高应变区域与实验标本吻合良好。第二次模拟用于分析骨折后碎片向椎管内的投射。结果表明，后纵韧带被拉伸，在较高能量下，脊髓和硬脑膜被碎片挤压。这些结构在迫使碎片回到椎体之前变形到最大程度。因此，碎片的最终位置并不代表最大动态椎管阻塞。
