摘要
目的比较3种不同后路内固定方式及其有无横连杆治疗胸腰段骨折的生物力学性能差异,寻找最优化的后路内固定方式。方法在已验证的正常T12~L2有限元模型基础上,模拟L1椎体爆裂性骨折。将T12椎体上半皮质骨切除并赋予内部松质骨损伤材料属性,分别建立无、有横连杆经伤椎单侧螺钉（模型A1、A2）、常规短节段（模型B1、B2）和经伤椎双侧螺钉（模型C1、C2）6种内固定模型。分别比较6组模型在各种生理应力下的活动范围（range of the motion,ROM）以及螺钉和棒的最大Von Mises应力情况。结果在屈伸和侧屈应力下,经伤椎单侧和双侧螺钉内固定模型组ROM均明显小于常规短节段内固定组;而经伤椎单侧和双侧螺钉内固定组,在屈伸应力下两者ROM无显著差异,在侧屈应力下经伤椎双侧螺钉模型的稳定性优于经伤椎单侧螺钉固定。应力主要集中在上位螺钉钉尾和上位螺钉与伤椎螺钉之间的棒体,经伤椎双侧内固定组上位螺钉最大应力明显低于经伤椎单侧和常规短节段内固定组螺钉最大应力。横连可增加各内固定组在扭转应力下的稳定性,也可降低上位螺钉和棒在扭转应力下的最大应力,而屈伸和侧屈应力下螺钉和棒的最大应力未见明显差异。结论经伤椎置钉后路内固定可获得较好的生物力学稳定性,且添加横连不仅能改善构型扭转刚度,而且能降低螺钉和棒的最大扭转应力,是治疗胸腰椎不稳定骨折良好选择。
Objective To compare the biomechanical differences among 3 posterior fixation methods with or without crosslink for thoracolumbar fractures to find the optimal treatment. Methods By using the validated finite element model of T12-L2 segments,L1 vertebra burst fracture was simulated followed with the superior 1 /2 cortical bone of T12 segment removed,and the superior 1 /2 cancellous bone was assigned with the material damage property of cancellous bone. Then 6 thoracolumbar fracture models by using intermediate unilateral pedicle screw fixation without or with crosslink（ Model A1,A2）,traditional short-segment pedicle screw fixation without or with crosslink（ Model B1,B2）,intermediate bilateral pedicle screw fixation without or with crosslink（ Model C1,C2）were established,respectively. The range of motion（ ROM）,the maximum Von Mises stresses of the pedicle screws and rods in the 6 models under various physiological loading conditions were compared. Results The ROM under flexion-extension and lateral bending in Model A and Model C was obviously smaller than that of Model B. Under flexion-extension,no significant difference was found in ROM between Model A and Model C; under lateral bending,the ROM of Model C was smaller than that of Model A. The stress was concentrated on the root of upper screw and rob located between upper screw and intermediate screw; the maximum stress of upper screw in Model C was smaller than that in Model A and Model B. The crosslink could increase the stability in all fixation groups under axial rotation stress condition,and decrease the maximum stress on upper screw and rod under axial rotation stress condition,but no significant difference was found under flexion-extension and lateral bending. Conclusions Additional pedicle screws at the level of fracture vertebra can achieve the better biochemical stability. The additional crosslink not only increases the torsional rigidity,but also decreases the maximum torsional stress of the screw and rod,which is a better choice for thoracolumbar fractures treatment.
出处
《医用生物力学》
EI
CAS
CSCD
北大核心
2016年第2期142-147,共6页
Journal of Medical Biomechanics
基金
广东省卫生厅医学科研基金(2014B2014175)
卫生部医药卫生科技发展研究中心资助课题(W2014ZT256),卫生部医药卫生科技发展研究中心资助课题(W2012ZT0)
关键词
胸腰段骨折
横连
内固定
力学特性
有限元分析
Thoracolumbar fractures
Crosslink
Internal fixation
Mechanical properties
Finite element analysis
