经椎间孔腰椎椎间融合术植骨融合前后应力分布差异的有限元分析  

Finite element analysis of stress distribution before and after segment fusion in transforaminal lumbar interbody fusion model

作　　者：李杰[1] 王洪岗[1] 尚进[1] 周跃[1] 

机构地区：[1]第三军医大学新桥医院骨科,重庆400037

出　　处：《第三军医大学学报》2015年第14期1449-1454,共6页Journal of Third Military Medical University

基　　金：重庆市科技攻关重大项目(CSTC2012GG_YYJSB10012);国家科技支撑计划(2012BAI14B02)~~

摘　　要：目的建立人正常L3~S1节段三维有限元模型,分析腰椎经椎间孔椎间融合术椎间植入物融合前后固定节段的生物力学特性。方法基于人正常L3~S1节段的CT扫描数据,应用逆向工程软件建立人正常L3~S1三维有限元模型（INT）,并构建L4~L5节段经椎间孔腰椎椎间融合术（transforaminal lumbar interbody fusion,TLIF）模型,进一步建立未融合未固定模型（M1）、未融合椎弓根螺钉固定模型（M2）、椎弓根螺钉固定融合模型（M3）、融合后去固定模型（M4）。在L3上表面施加500 N预载荷,再施加7.5 N·m的力矩模拟腰椎前屈、后伸、侧屈及旋转,观察不同工况下L4~L5节段角位移、椎弓根螺钉及融合器应力分布情况。结果 M1模型L4~L5节段ROM值较INT增加,其中左旋状态最明显。M2、M3和M4模型的ROM值接近并且较INT明显减少。M3模型中内固定应力峰值较M2模型明显降低,M1椎间植入物应力峰值显著高于其他模型而M2、M3和M4模型的应力峰值相近。结论成功构建人正常L3~S1节段三维有限元模型。双侧椎弓根钉-棒内固定可以有效控制节段稳定性并减少椎间植入物承受载荷,植骨融合后其承受的应力峰值将会减少。融合后去除后路内固定对节段生物力学获益有限,考虑到二次手术的创伤和费用,建议保留内植物。Objective To build a normal L3- S1 segment finite element model,and analyze the biomechanical difference before and after segment fusion in transforaminal lumbar interbody fusion（ TLIF）model. Methods The normal L3-S1 segment CT data were used to rebuild the intact finite element（ INT）model by software. The TLIF model was rebuild by right side facetectomy and discectomy,and a cage was inserted into the disc. Based on the TLIF model,an unfused model without fixation（ M1）,an unfused model with bilateral pedicle screw fixation（ M2）,a fused model with bilateral pedicle screw fixation（ M3）,and a fused model without fixation（ M4） were built. A 500 N preload with 7. 5 N·m moment was applied to the surface of L3 segment to induce the flexion-extension,left-right lateral bending and left-right axial rotation.The L4- L5 segment range of motion（ ROM） and the stress distribution of the pedicle screw-rod system and interbody fusion cage were observed. Results ROM was increased in the M1 model compared with the INT model,obviously in left axial rotation. ROM was similar to each other in the M2,M3 and M4 models,and was decreased compared with the INT model. The peak Von Mises stress of the pedicle screw-rod system in the M3 model was decreased compared with the M2 model. The peak Von Mises stress of the interbody infusion cage was similar in the M2,M3 and M4 models,but was obviously less than that in the M1 model.Conclusion A normal L3- S1 segment finite element model is successfully established. Pedicle screw-rod system instrumentation can effectively control the stability of the index segment and reduce the load applied to the interbody fusion cage. The peak Von Mises stress of posterior instrumentation is decreased after fusion. It is unnecessary to remove posterior instrumentation after fusion considering the limited biomechanical benefit and the surgery cost.

关 键 词：经椎间孔腰椎椎间融合术 生物力学 应力分布 有限元分析 

分 类 号：R318.01[医药卫生—生物医学工程] R319[医药卫生—基础医学]