可视化方法分析椎体成形术前弯状态下的力学形态  

Vertebral mechanics under flexion before vertebroplasty: A visualized analysis

作　　者：孙伟娜[1] 李海云[1] 田新[1] 杨新建[2] 

机构地区：[1]首都医科大学生物医学工程学院,北京市100069 [2]北京神经外科研究所,北京市100050

出　　处：《中国组织工程研究与临床康复》2008年第39期7641-7644,共4页Journal of Clinical Rehabilitative Tissue Engineering Research

基　　金：国家自然科学基金资助项目(30670576);北京市自然科学基金资助项目(3062006)~~

摘　　要：背景:椎体成形术是通过椎弓根向椎体内注入骨水泥以增加椎体的抗压性,预防椎体进一步塌陷和再骨折发生。目的:比较椎体成形术前后,L1～2在前弯力矩作用下的力学特征改变。设计、时间及地点:基于影像特征的椎体成形术的三维有限元分析,于2005-10/2006-06在北京市神经外科研究所完成。对象:1例54岁女性患者,经CT确诊为骨质疏松且伴有L1～2压缩性骨折,患者对实验项目知情同意。实施术前术后的C扫描,获取L1～2节段断层图像各90张,层厚0.75mm。方法:应用图像分割及三维重建算法提取腰椎组织CT图像中的解剖结构特征,建立了L1～2腰椎组织三维几何模型。在几何模型的基础上,分别建立椎体成形术术前和术后L1～2的腰椎段三维有限元模型。主要观察指标:在椎体的上表面分别施加10N·m的前弯力矩,观察有限元模型L1～L2段的应力、应变的分布变化。结果:①前弯力矩下,椎体成形术术后椎体的最大应力应变值较术前无明显变化,但应力应变分布都有了明显的改变,骨水泥附近明显增高。②最大的应力值出现在椎间盘上表面,与其相邻的L2椎体应力明显增高,产生应力转移的现象,容易增加L2椎体压扁变形的破坏性。高应力值出现在腰椎前部,表示前部受到较大的应力导致变形。结论:建立了椎体成形手术前后L1～2段椎体三维有限元模型,证实骨水泥能在一定程度上恢复椎体单元的硬度和强度。BACKGROUND： Percutaneous vertebroplasty （PVP） can strengthen vertebral hardness by injecting bone cement into the vertebral body to prevent further vertebral collapse or re-fracture. OBJECTIVE： To compare mechanical changes of lumber spinal segment L1-2 under flexion before and after vertebroplasty. DESIGN, TIME AND SETTING： Three-dimensional （3D） finite element analysis based on PVP was performed at the Beijing Neurosurgical Institute between October 2005 and June 2006. PARTICIPANT： One 54-year-old female patient with compressibility fracture at lumbar vertebrae L1-2 induced by osteoporosis is was diagnosed with CT examination, and the informed consent was obtained from her. Based on CT scanning before and after PVP, 90 serial sections with the thickness of 0.75 mm were obtained. METHODS： By extracting anatomical structure using image segmentation and reconstruction approaches from CT images, a 3D geometric model of the lumber spinal segment L1-2 was established. Based on the geometric model, 3D finite element models of segments of preoperative and postoperative vertebrae were created. MAIN OUTCOME MEASURES： Stress and strain distributions of finite element model at L1-2 segment under flexion （10 N.m） between pre- and post-vertebroplasty. RESULTS： There was no significant change in maximum stress-stain values between pre- and post-PVP. However, stress-stain distribution changed greatly especially increased near the bone cement. The region of maximum stress value was on the superior surface of the vertebral disc. With the increase of stress on L2 segment, it could induce transfusion of load of nearby vertebral body. High stress was found in the prevertebral part induced by high stress. CONCLUSION： Three-dimensional finite element model of L1-2 segments for pre- and post-PVP were built. It has proved that bone cement may help to the restoration of intension and hardness to a certain extent.

关 键 词：椎体成形术 前弯力矩 应力 物理 有限元分析 

分 类 号：R318[医药卫生—生物医学工程]