Biomechanical changes of lumbar segment after fusion analyzed with three-dimensional nonlinear finite element

doi:10.3969/j.issn.2095-4344.2013.35.009

Abstract

Abstract:

BACKGROUND: MATLAB has capabilities of large numerical calculation, mathematical drawing and simple finite element analysis. It can establish models rapidly and can be able to identify the grayscale with BMP and JPG format, and it can directly transform the identified data into ANSYS finite element software-readable format, thus avoiding personal error produced by the repositioning and secondary treatment in the Autocad software.
OBJECTIVE: To find a simple, convenient and accurate method to construct the model of lumber fusion and to analyze the biomechanics of lumbar motion segment after lumbar fusion.
METHODS: Lamellar CT and Matlab (Matrix Laboratory) scientific computing software combining Ansys finite element software was used to construct the models of lumber fusion. Then the models were loaded to analyze the biomechanical change of the fusion model.
RESULTS AND CONCLUSION: The established models were loaded with axial, bending and stretching loads, and the biomechanical analysis showed that interbody fusion had the best stability among all the fusion models. Combined with joint fusion, the axial displacements of interbody, rear side and rear fusion models were decreased by 5%, 1% and 4% than that of simple interbody fusion, posterolateral fusion and posterior fusion models. Under the stretch-buckling load conditions, the rotation angles were reduced by 23%, 11% and 45%. Stress concentration to the fusion parts showed fusion block could increase the load displacement. The technology of lamellar CT, Matlab software and Ansys finite element software can accelerate the construction of lumber fusion model and make the model more accurate. Facet joint fusion combined with interbody fusion, posterolateral fusion and posterior fusion can get better lumbar stability, and this increased stability is more significant in the rear fusion. Stress distribution of posterior fusion is more reasonable.

Key words: bone and joint implants, basic experiment of spinal cord injury, bone tissue engineering, biomechanics, finite element method, lumbar fusion, facet joint fusion, fusion model, loading, matrix laboratory

CLC Number:

R318

Zhang Yan-hui, Jiang Hong-chun, Li Jing, Zhang Bao-di. Biomechanical changes of lumbar segment after fusion analyzed with three-dimensional nonlinear finite element[J]. Chinese Journal of Tissue Engineering Research, 2013, 17(35): 6273-6280.

Figures/Tables 6

轴向位移：轴向压缩载荷下椎体间融合合并小关节融合的轴向位移最小，而后按照轴向位移从小到大的顺序模型依次是椎体间融合无小关节融合、侧后方融合合并小关节融合、侧后方融合无小关节融合、后方融合合并小关节融合、小关节融合、后方融合无小关节融合和正常模型。合并小关节融合的模型较无小关节融合的同样模型轴向位移小，稳定性好。椎体间融合合并小关节融合、侧后方融合合并小关节融合和后方融合合并小关节融合的稳定性较椎体间融合无小关节融合、侧后方融合无小关节融合和后方融合无小关节融合分别增加5%、1%和4%。这些数据表明小关节融合可以增加稳定性。伴随的屈曲旋转：轴向压缩载荷下，正常模型和椎体间融合模型都很少有屈曲旋转，但在其他模型中，可以看到屈曲旋转。轴向压缩载荷下小关节融合模型的屈曲旋转角度最大，其他模型从大到小依次是后方融合合并小关节融合、侧后方融合合并小关节融合、侧后方融合无小关节融合、和后方融合无小关节融合。屈曲和伸展载荷下的运动：椎体间融合合并小关节融合屈曲和伸展方向的稳定性最好，其他模型稳定性由大到小依次是椎体间融合无小关节融合、侧后方融合合并小关节融合、后方融合合并小关节融合、小关节融合、侧后方融合无小关节融合和正常模型，见图8。后方融合合并小关节融合、小关节融合和侧后方融合无小关节融合的旋转角度几乎相同。与椎体间融合无小关节融合、侧后方融合无小关节融合、后方融合无小关节融合相比，椎体间融合合并小关节融合、侧后方融合合并小关节融合、后方融合合并小关节融合屈曲和伸展方面的稳定性分别增加了23%、11%和45%。以上数据表明小关节融合可增加在屈曲和伸展方面的稳定性，这种稳定性的增加在后方融合模型中最为明显。"

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