腰椎“U”形弹性内固定器的研制及力学评价  

Design and Finite Element Analysis of A "U" Shape Dynamic Fixation System for Lumbar Spine

作　　者：于博[1] 靳安民[1] 方国芳[1] 冯伟[1] 王宇[1] 薛剑[1] 

机构地区：[1]南方医科大学珠江医院骨科,广东省广州市510282

出　　处：《中国骨与关节损伤杂志》2009年第8期698-701,共4页Chinese Journal of Bone and Joint Injury

基　　金：广东省科技计划项目(2007B031003010);2006年广东省重大科技专项(2006A36001003-08);广东省医学科研基金(WSTJJ2007102344010519780525258019)

摘　　要：目的介绍腰椎"U"形弹性内固定器的研制,并利用有限元方法对其生物力学特性进行评价。方法采用镍钛合金设计一种腰椎弹性内固定器。选择1名成年男性志愿者,以L4、5节段为研究对象,采用螺旋CT对其进行层厚1.0 mm的连续水平扫描,借助Mimics 11.11软件,建立L4、5节段三维非线性有限元模型。同时根据椎弓根螺钉、连接棒的几何尺寸及力学参数分别添加螺钉和连接棒模型,建立腰椎"U"形弹性内固定的三维有限元模型,分别施加垂直压缩、前屈、后伸、侧屈及旋转等各种生理载荷,对不同载荷下模型各部分的应力进行观察和分析。结果弹性内固定系统各部分于垂直压缩时所受应力远小于其他状态(P<0.001);不同载荷下应力主要分布在"U"形弹性棒上,螺钉各部受力较为均匀。结论腰椎"U"形弹性内固定器设计独特,能减少术后应力遮挡及椎弓根螺钉应力集中,有望成为较好地进行腰椎弹性内固定的一种装置。Objective To introduce the design and evaluate the biomechanical properties of a U shape dynamic fixation system for lumbar spine with finite element method. Methods The L4.5 motion segment data were obtained from CT scans （at 1.0 mm width increments） of the lumbar spine of an adult man. After these images were processed, a three- dimensional finite element model of the L4,5 was established by Mimics 11.11. Meanwhile, the three-dimensional finite element model of the vertebral pedicle screw and U rod were established by Mimicsl 1.11. According to the above mentioned, the L4,5 model was combined with the model of the vertebral pedicle screw and U rod, and the three- dimensional finite element model of the L4,5 U shape dynamic fixation was established. Loads used in this study were axial compressive, flexion, extension, lateral bending, and rotation forces. The distribution of von mises stress of the fixation segment were analyzed and compared. Results In the same shearing load of 500 N, the stress of the U shape dynamic fixation system was lower at axial compressive than flexion, extension, lateral bending, and rotation forces （P〈0.001）. The stress of the U shape dynamic fixation system for lumbar mainly concentrated on the U shape elastic rod, and the stress distribution of the vertebral pedicle screw was comparatively uniform. Conclusion The U shape dynamic fixation system has a unique design, which can reduce the stress block and stress concentration of the vertebral pedicle serew, may be a better fixation instrument for the lumbar degenerative disease.

关 键 词：弹性内固定 形状记忆合金 有限元分析 生物力学 

分 类 号：R683[医药卫生—骨科学] R318.01[医药卫生—外科学]