Three-dimensional finite element analysis on the support and protection of spine protector for thoracic-lumbar vertebra

doi:10.3969/j.issn.2095-4344.2014.40.024

Abstract

Abstract:

BACKGROUND: Human spine protector can protect human thoracic-lumbar vertebra segments against injury, and the design and development of a novel dynamic protector needs the verification of various experimental means.

OBJECTIVE: Using the three-dimensional finite element method, we evaluate the effect of spine protector and the biomechanical reaction of thoracic-lumbar vertebra under the axial loading.

METHODS: The thoracic-lumbar vertebra were cut from the whole spine three-dimensional finite element model. Then the thoracic-lumbar vertebra models carrying spine protector were taken as experimental group, while the models without the protector served as control group. All the specimens were evaluated, constrained, loaded and figured out by its properties. The results of equivalent stress and strain distribution were obtained from the data.

RESULTS AND CONCLUSION: In both groups, the stress was distributed at axial and posterior column of L₂ when the load was applied in axial direction. According to the data obtained from the experiment, both the experimental group and the control group had achieved the maximum stress at 16 ms, 3.919 Mpa and 5.727 MPa, respectively. The statistical analysis result showed that the stress varied significantly at T₁₂ and L₂ in two groups (both P < 0.05). However, the stress distribution at T₁₁ and L₁ showed no significant difference between the two groups (both P > 0.05). Experimental findings indicate that, spine protector can significantly reduce the vertical stress of the thoracic-lumbar vertebra when falling on the ground, and share the vertical load, which is protective to thoracic-lumbar vertebra.

中国组织工程研究杂志出版内容重点：人工关节；骨植入物；脊柱；骨折；内固定；数字化骨科；组织工程

全文链接：

Key words: thoracic vertebra, lumbar vertebra, finite element analysis, biomechanics

CLC Number:

R318

He Jian-ying, Deng Liang, Li Chen, Wu Xiao-hui, Shu Yong, Dong Xie-ping. Three-dimensional finite element analysis on the support and protection of spine protector for thoracic-lumbar vertebra[J]. Chinese Journal of Tissue Engineering Research, 2014, 18(40): 6536-6541.

Figures/Tables 4

2.1 胸腰椎模型各节段等效应力变化规律及对比分析在整个实验过程中，实验组和对照组胸腰椎各椎体所受应力均随时间增加而增大，在一定时间达到峰值以后逐渐下降。4个椎体的平均承受应力降幅如表2所示分别达11.1%，42.5%，13.5%，31.5%。根据图4发现实验组各椎体受力曲线较对照组更均匀平缓。采集目标单元的最高等效应力数据显示，对照组T11，T12，L1，L2所受应力峰值分别为3.62，4.72，3.72，5.73 MPa；而实验组胸腰椎所受应力峰值分别为3.22，2.71，3.22，3.92 MPa。除T11椎体以外，其余3个椎体的等效应力峰值均出现在实验过程的16 ms。将对照组各椎体受力平均值与实验组各椎体受力平均值求差值，作平均值差值曲线，根据平均值差值曲线图分析，T11椎体平均值差值接近0，即脊柱保护支具对T11椎体保护作用不大。而T12，L1，L2椎体平均值差值随时间增加而保护作用逐渐增大，在15-20 ms区间内，T12，L1，L2椎体的平均值差值最大值分别为2.31，0.80，1.80 MPa。脊柱保护支具的使用对胸腰段椎体所受力总体上有减小作用。 2.2 垂直载荷作用下两组胸腰段模型等效应力具体分布特点及变化规律通过Abaqus软件动态截取整个仿真过程两组模型的应力分布模型图，发现在实验前半阶段(0-10 ms)无论实验组模型还是对照组模型未出现明显的应力增亮区域。从11 ms开始应力逐步随时间推移集中于本实验前设定的4个研究目标单元中的B区、C区和D区内，直至16 ms实验组模型与对照组模型达到应力峰值见图5，而后两组模型应力增亮区逐渐降低。根据图6发现，脊柱胸腰段所受应力主要集中于椎体后缘、关节突关节、椎弓根及椎板处。其中无论实验组还是对照组模型L2椎体应力峰值最大。在实验整个过程中，根据两组模型图发现，同一时间节点比较，对照组模型应力增亮区均高于实验组模型应力增亮区，说明佩戴脊柱保护器能有效降低胸腰段应力。 2.3 统计分析结果使用SPSS 15.0分别对T11，T12，L1，L2实验组与对照组的目的区域收集的等效应力平均值进行配对样本t 检验，其中T12节段P=0.022，L2节段P=0.012， P均< 0.05，故在95%的置信水平下，配戴脊柱保护器差异有显著性意义。而T11节段P=0.936，L1节段P=0.305，P > 0.05，故在95%的置信水平下，配戴脊柱保护器的差异不明显，差异无显著性意义(表3，4)。"

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