前路腰椎间融合后路关节突螺钉固定术螺钉应力的有限元研究  

Screw stress feature of different facet fixations of anterior lumbar interbody fusion (ALIF) based on a three- dimensional finite element method

作　　者：敖俊[1] 靳安民[1] 方国芳[1] 冯伟[1] 张辉[1] 于博[1] 薛忠林[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》2008年第4期429-432,共4页Chinese Journal of Clinical Anatomy

基　　金：广东省科技厅重大专项基金课题(2006A36001003-08)

摘　　要：目的:建立L4,5节段的三维有限元模型,比较研究前路腰4/5椎间双枚椎间融合器(cage)融合加后路两种关节突螺钉内固定(TLFS和TFPS)后的应力特点。方法:选择一名青年自愿者的正常腰椎,进行螺旋CT层厚0.625mm的连续水平扫描,将所得的数据以Dicom格式转入计算机,借助Mimics11.1软件,建立L4-5节段的几何模型。将几何模型转入Simpleware2.1软件,同时将螺钉和cage以STL格式转入Simpleware软件进行匹配,模拟前路椎间双枚cage融合加后路TLFS固定、前路椎间双枚cage融合加后路TFPS固定等两种临床术式,从而建立TLFS和TFPS有限元模型,导入Abaqus6.51进行分析,在L4椎体上表面施加500N压力模拟轴向压缩、再施加10Nm的力矩模拟腰椎前屈、后伸、侧屈和旋转等各种生理载荷,观察不同载荷下螺钉的应力分布,并由此对两种关节突螺钉应力的特点进行比较。结果:两种关节突螺钉在关节突关节部应力集中明显;在每种螺钉中,其关节突关节部应力值均在轴向压缩载荷下最小,在侧屈时最大;两种关节突螺钉的关节突部应力在各种生理载荷下比较,TLFS均明显大于TFPS(P<0.01)。结论:在前路椎间融合的前提下,从减少螺钉疲劳断裂可能性角度,应首选TFPS辅助固定。两种关节突螺钉辅助固定术后均需有效外固定以减少螺钉应力集中可能引起的螺钉断裂。Objective： To develop a 3D finite element model of the different facet screws fixation and evaluate the stress of facet screw in anterior lumbar interbody fusion （ALIF）. Methods： The geometrical model was created by Mimics 11.1 based on CT data of L4.5 motion segment from a 32- year- old man. Different facet screws and cages geometrical model were dealt with as the same procedure. Subsequently, the above models were imported into the Simpleware 2.1 in order to establish the 3D finite element models of ALIF with double fusion cages and posterior translaminarfacet screw （TLFS）, transfacetopedicular facet screw （TFPS） fixation respectively. The 3D finite element models were imported into Abaqus 6.51 and analyzed. 500N pressure was loaded on the upper surface of L4, 10 Nm moments was loaded to simulate lumbar axial compression, anteflexion, extension, lateral bending and rotation. The Von mises stress of the facet screws was recorded and input into Spss 16.0 to analyze the difference of different stress distribution of the two fixations. Rosults： It was obviously that the Von mises of the screws concentrated on the facet joint part. The mean Von mises stress of all loadings of TLFS and TFPS fixation, axial compression load was minimal and the lateral bending was maximal. The mean Von mises stress of TLFS fixation of different loading was larger than that of TFPS fixation （P〈0.01）.Conclusions： The TFPS fixation can be considered as a good alternative to TLFS fixation to avoid the breakage risk of the screws. It is necessary to limit patients＇ activities by a waist-brace protection after operation.

关 键 词：关节突固定 脊柱融合术 生物力学 有限元分析 

分 类 号：R318.01[医药卫生—生物医学工程]