Duan S, Zhu Z Q, Wang K F, Liu C J, Xu S, Xia W W, Liu H Y
Department of Spine Surgery, Peking University People's Hospital, Beijing 100044, China.
Zhonghua Yi Xue Za Zhi. 2018 Mar 20;98(11):837-841. doi: 10.3760/cma.j.issn.0376-2491.2018.11.009.
To establish a three-dimensional (3D) finite element (FE) model of the whole cervical spinal cord (WSCS) and explore the biomechanical behaviors of cervical spinal cord injury related to different bone fragment impact velocities by FE analysis. A 3D FE model of WCSC was established based on the morphologic data of each segment of the human cervical cord. The reconstruction structures, which included the dura mater, the cerebrospinal fluid, the gray and white matter in the C(2) to C(7) cervical vertebrae, were validated.On the validated WCSC model, three kinds of pellets with same mass (7 g) but different impact areas (314, 157 and 78.5 mm(2)) were created to represent the bone fragments.These were positioned in the middle of the spinal cord to impact at various initial velocities.The maximum of von Mises stress and the reduction of the cross-sectional area (CSA) of the spinal cord were measured from each impact. The compression of WCSC (percentage) and the time to reach maximum compression were similar with the results reported in literatures, indicating the validity of the model.Regardless of the impact areas of the pellet, the maximum of von Mises stress and the reduction of CSA of the spinal cord increased with the increased velocity.The maximum of von Mises stress was 5.0-7.0 kPa at a pellet velocity of 1.5 m/s, and the reduction of CSA was 9.3%-12.3%.At a velocity of 3.5 m/s, the maximum of von Mises stress was 42-54 kPa and the reduction of CSA was over 30%.The stress of the spinal cord significantly increased when pellet velocity exceeded 3.5 m/s, and the fastest increase was recorded at 4.5 m/s.The von Mises stress of the spinal cord ranged between 240 and 320 kPa at a velocity of 6.0 m/s, and CSA decreased by more than 50%. The 3D FE model of WSCS could provide more insights on the biomechanical mechanisms of spinal cord injury through various bone fragment impacts in burst fracture.When the impact velocity of the bone fragment exceeds 3.5 m/s, the maximum stress significantly increases and the reduction of CSA of the spinal cord is over 30%, and this could possibly lead to the contusion injury of the spinal cord.
建立全颈脊髓（WSCS）的三维（3D）有限元（FE）模型，并通过有限元分析探讨与不同骨碎片撞击速度相关的颈脊髓损伤的生物力学行为。基于人颈髓各节段的形态学数据建立了WCSC的3D FE模型。对包括硬脑膜、脑脊液、C2至C7颈椎的灰质和白质在内的重建结构进行了验证。在经过验证的WCSC模型上，创建了三种质量相同（7 g）但撞击面积不同（314、157和78.5 mm2）的小球来代表骨碎片。将这些小球置于脊髓中部，以不同的初始速度进行撞击。每次撞击后测量脊髓的最大冯·米塞斯应力和横截面积（CSA）的减小量。WCSC的压缩率（百分比）和达到最大压缩的时间与文献报道的结果相似，表明该模型的有效性。无论小球的撞击面积如何，脊髓的最大冯·米塞斯应力和CSA的减小量均随速度增加而增加。小球速度为1.5 m/s时，最大冯·米塞斯应力为5.0 - 7.0 kPa，CSA减小量为9.3% - 12.3%。速度为3.5 m/s时，最大冯·米塞斯应力为42 - 54 kPa，CSA减小量超过30%。当小球速度超过3.5 m/s时，脊髓应力显著增加，在4.5 m/s时增加最快。速度为6.0 m/s时，脊髓的冯·米塞斯应力在240至320 kPa之间，CSA减小超过50%。WSCS的3D FE模型可以通过爆裂骨折中各种骨碎片撞击为脊髓损伤的生物力学机制提供更多见解。当骨碎片撞击速度超过3.5 m/s时，最大应力显著增加，脊髓CSA减小超过30%，这可能导致脊髓挫伤。
