经椎间孔腰椎间融合三维有限元分析

Three-Dimensional Finite Element Analysis of Transforaminal Lumbar Interbody Fusion

利用有限元法研究经椎间孔腰椎间融合术(TLIF)中融合器的植入位置角度对椎弓根螺钉固定腰椎运动学和生物力学特性的影响规律.基于健康成年男性腰椎CT影像重建三维模型,再利用有限元软件Hypermesh建立了腰椎L4-L5节段正常有限元模型以及按不同角度(30°,45°,60°)植入融合器的椎弓根螺钉单/双边固定的融合模型,比较分析了各模型在前屈、后伸、侧弯和轴向旋转生理活动下的腰椎活动范围、融合器与椎间盘上下终板接触界面以及融合器自身应力分布等生物力学特性.结果表明,在相同的生理活动下,融合模型活动范围值均较正常模型大幅降低.融合器和接触界面上应力分布随着生理活动和融合器植入角度不同存在差异.综合考虑生物力学性能和融合节段的稳定性,融合器斜向45°植入配合单边椎弓根螺钉固定为相对较好TLIF术.

By using the finite element method,this paper investigated the effect of cage insertion on the kinematic and biomechanical behavior of low lumbar spine segment with various transforaminal lumbar interbody fusion（TLIF）surgical operations.Based on CT images of a healthy male adult,a three-dimensional（3D）model of lumbar vertebras L4-L5 segments was reconstruction and meshed by using Hypermesh.Biomechanical analysis of intact and TLIF operated L4-L5 segment models under various physiological loading conditions including flexion,extension,lateral bending and axial rotation was implemented with commercial CAE software ABAQUS.Sugical operations with unilateral and bilateral pedicle screw fixations plus one cage interbody fusion with different implanted angles（30°,45°,60°）were investigated.ROMs and stress distributions in cages and cage-endplate interfaces were obtained and compared.The simulation results show that under the same loading condition,the ROMs in fusion models are significantly lower thanthe coresponeding normal ones.The stress distributions in cage and cage-endplate contact surface significantly change with the variation of cage implant angle.In conclusion,for lowering peak stresses in cage with contact interface and stabilizing the fused lumbar segments,unilateral pedical screws fixation plus one cage with a 45°implant angle is possibly the best choice in TLIF treatment.