目的　建立T6～8椎体病灶清除植骨+后路经肋椎单元固定系统三维有限元模型，分析系统所受应力对其进行改进。  方法　获得1例男性（身高172 cm，体质量71 kg，39岁）T7椎体结核病患进行螺旋CT扫描，将所得数据导入计算机，通过Mimics13.0软件和Ansys11.0有限元软件建立T6～8后路病灶清除植骨+经肋椎单元固定系统三维有限元模型，并在在椎体上表面施加500 N压力和10Nm的力矩模拟腰椎前屈、后伸、侧屈3种生理载荷，观察不同载荷下固定器械的应力分布，并对其进行比较。  结果　在前屈和后伸运动状态下，螺钉尾部是应力最为集中的部位，上位螺钉大于下位螺钉，对于纵连棒，上端总是大于下端，且下端应力为零；侧弯位，螺钉尾部应力均较前屈和后伸位减小；纵连棒上下端应力相当。同一部位三种运动状态下比较，螺钉尾部总是后伸位大于前屈位，侧弯位最小；纵连棒E,F点，总是前屈大于后伸，侧弯最小；侧弯位纵连棒末端最小。  结论　T6～8运动节段后路椎间植骨经肋椎单元内固定的病人在做前屈和后伸运动时上位螺钉尾部及纵连棒的上端最容易发生疲劳性断裂。

Objective　To develop a 3-D finite element(FE) model of bone graft with vertebral debridement and posterior vertebral unit fixed system through ribs of T6~8.　Methods　Spiral CT data of one male patient (172 cm, 71 kg, 39-year-old) with T7 vertebraltuberculosis were imported into computer to develop a 3-D FE model of bone graft with vertebral debridement and posterior vertebral unit fixed system by ribs of T6~8 by Mimics13.0 and Ansys11.0 finite element software. 500N pressure and 10Nm torque to the vertebral surface by 3 kinds of physiological load which simulating flexion, extension and lateral bending were exerted. The stress distribution of fixation devices under different loads was compared.　Results　At the positions of anteflexion and extension, the stress mainly concentrated to screw tail, and stress of the upper screw was greater than the lower screw, stress of the top was always greater than the bottom. At lateral bending position, stress of screw tail was less than that at flexion and extension. Stress was identical at the top and bottom of the vertical rods. For 3 different dynamics at the same points, stress of the extension was greater than anteflexion, stress of the anteflexion was greater than lateral bending at screw tail. Stress of anteflexion was greater than extension, and stress of the extension was greater than lateral bending at E and F points of vertical rods. Stress of vertical rod bottom at lateral bending was the least.　Conclusions　It prones to fatigue fracture at upper screw tail and the top of vertical rods by bone graft with vertebral debridement and posterior vertebral unit fixed system by ribs of T6~8 at the positions of anteflexion and extension.