腰椎弹性内固定与刚性内固定的应力对比研究  

Biomechanic comparision between the"U"shape lumbar dynamic fixation system and traditional fixation system

作　　者：于博[1] 靳安民[1] 方国芳[1] 闵少雄[1] 刘成龙[1] 田京[1] 敖俊[1] 

机构地区：[1]南方医科大学珠江医院骨科,广州510282

出　　处：《中国临床解剖学杂志》2009年第4期469-473,共5页Chinese Journal of Clinical Anatomy

基　　金：广东省重大科技专项(2006A36001003-08);广东省科技计划项目(2007B031003010);广东省医学科研基金(WSTJJ20071023440105197805258019);卫生部卫生行业科研专项项目(200802017)

摘　　要：目的:通过有限元的方法评价自行研制的腰椎"U"型弹性内固定器的力学特性,并与传统的刚性内固定器进行比较。方法:选择一名成年患者腰椎标本,以L4～5节段为研究对象,采用64排螺旋CT对其进行层厚1.0mm的连续水平扫描,将所得图像进行轮廓提取和阈值分割后,借助三维重建软件Mimics11.1、Simpleware和有限元软件Abaqus6.51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,力学参数,分别建立两种不同内固定器的有限元模型。然后分别施加压缩、前屈、后伸、侧屈及旋转等各种生理载荷,观察各模型不同载荷下螺钉、连接棒的应力分布。结果:两种内固定器的椎弓根螺钉前、中部的应力差异无统计学意义(P>0.05);刚性固定的椎弓根螺钉与棒连接处是应立集中的部位,该部位的应力远大于弹性固定器,而弹性内固定应力集中的部位均匀的分布于整个U型连接棒上,两模型固定节段螺钉及棒的最大有效应力均出现于前屈时。结论:在加载相同的纵向载荷条件下,刚性内固定器应力主要集中在螺钉与棒交界处,容易易发生螺钉断裂,U型弹性内固定器的应力均匀分布在U型连接棒上,可以减少断钉的现象发生。Objeotive： To compare biomechanical features between the new “U” shape lumbar dynamic fixation system and traditional rigid fixation system. Methods： Finite element analysis of the two fixation systems were performed on the basis of a three-dimensional model reconstructed from the images of CT scanning of an adult cadaveric lumbar with the interval of 1 mm. The stress and displacement of every nodule and element in the course of deformation of the internal fixation were tested and analyzed. Results： In the same shearing load of 500 N, The force of the dynamic fixation system concentrated on the “U” shape elastic zone, however, the force of the rigid fixation system concentrated on the posterior 1/3 of the lower screw. Conclusions： This study demonstrates the new “U” shape lumbar dynamic fixation system has a totally different biomechanical properties comparing to that of traditional rigid fixation system. This dynamic fixation system may be a choice to replace the rigid fixation system for the treatment of the lumbar degenerative disease.

关 键 词：有限元分析 弹性固定 刚性固定 记忆合金 

分 类 号：R322[医药卫生—人体解剖和组织胚胎学] R68[医药卫生—基础医学]