终板切除对终板-钛网界面应力分布影响的三维有限元分析

Three-dimensional finite element analysis of the mechanical changes of meshcage-endplate interface following endplate resection.

目的采用三维有限元法比较终板切除与否对颈椎椎体次全切除减压终板-钛网界面应力分布的影响。方法在正常人C4~C7三维有限元模型基础上,模拟颈椎（C5）椎体次全切除减压手术,建立颈椎前路减压、终板保留与不保留两种手术模型。利用Ansys9.0软件的建模功能建立12mm直径钛网（无垫片）、颈椎前路钢板以及螺钉模型,分别加载到颈椎前路减压手术模型上,建立终板保留与不保留钛网植骨前路钢板固定手术两种模型。对模型施加80N预载荷及1.8Nm力矩,使其产生轴向压缩、前屈和后伸运动,选取终板-钛网界面上下各7个接触点,分别记录各个点的von Mises应力及应变,比较终板保留与不保留对终板-钛网界面应力分布的影响。结果在各种工况下,保留终板钛网植骨C4下终板-钛网界面和C6上终板-钛网界面7个接触点的应力大于不保留终板钛网植骨C4下终板-钛网界面和C6上终板-钛网界面相应接触点的应力。应变情况正好相反,不保留终板钛网植骨C4下终板-钛网界面和C6上终板-钛网界面7个接触点的应变大于保留终板钛网植骨C4下终板-钛网界面和C6上终板-钛网界面相应接触点的应变。结论在颈椎前路椎体次全切除减压、钛网植骨融合手术中,保留终板钛网植骨能够降低终板-钛网界面的应变,降低钛网下沉的发生率。

Objective To evaluate the mechanical changes of meshcage-endplate interface in anterior cervical corpectomy and fusion by three-dimentional finite element analysis.Methods Three-dimentional finite element model was established for normal cervical 4-7 segments and then one model of preserving endplate and another model of without preserving endplate were made in anterior cervical corpectomy and fusion using titanium meshcage and plate.Mechanical changes were analized by Ansys 9.0 software after the two model were exerted 80 N pre-loads and 1.8 Nm moments of force to produce axial compression,anteflexion and backextension.Von Mises stress and the strain on the 7 contact points of superior and inferior meshcage-endplate interface were compared in the model of preserving endplate with the model of without preserving endplate.Results The stress of superior and inferior meshcage-endplate interface in the model of preserving endplate were bigger than that in the model of without preserving endplate.But the strain is contrary.The strain of superior and inferior meshcage-endplate interface in the model of preserving endplate were smaller than that in the model of without preserving endplate.Conclusion Preserving endplate could decrease the strain of meshcage-endplate interface and increase the resistance to meshcage subsidence in anterior cervical corpectomy and fusion