单节段后路内固定对于胸腰段单椎体压缩骨折的生物力学分析

Single segment posterior fixation for single thoracolumbar vertebral compression fractures:a biomechanical analysis

[目的]对于单节段后路钉棒系统内固定器治疗胸腰段单椎体压缩骨折进行生物力学测试,为此种手术方法在临床上的应用提供生物力学支持。[方法]取36具冰冻家猪胸腰段椎体标本,采用Panjabi法制作预损伤模型,分为3组,每组12个样本,分别为单节段固定组,跨阶段固定组以及失稳组。分别对每组进行椎体强度、载荷-应变、稳定性与刚度、扭转强度、位移的生物力学测试。[结果]经过生物力学测试,椎体强度:单节段内固定组与跨节段内固定组相比,A点应力减少7.2%,B点应力减少16.8%(P<0.05)。单节段组与失稳组相比,A点应力减少13.9%,B点应力减少26.7%(P<0.05)。载荷-应变:单节段内固定组小于跨节段内固定组和失稳组,A点应力分别减少6.9%、13.8%。B点应力分别减少15.3%、30%(P<0.05)。水平位移:单节段内固定组比跨节段固定组和失稳组分别减少6.8%和40%(P<0.05)。纵向位移:单节段内固定组比跨节段固定组和失稳组分别减少13%和37%(P<0.05)。[结论]单节段后路内固定在生物力学上予以支持,临床可以应用。

[ Objective] To investigate the clinical application and its biomechanical support of single segment posterior ped- icle screw fixation system in treatment of single thoracolumbar vertebral compression fracture. [ Method] Thirty-six thoracolum- bar frozen specimens from pigs were selected as pre-injury model using Panjabi method. All specimens were divided into 3 groups with 12 samples in each group：single segment fixation group, cross-phase group, and instability of fixation group. Tests were carried out in each group, including vertebral body strength, load-strain, stability and stiffness, torsion strength, displace- ment aspects of biomechanics. [ Result] According to the biomeehanical test results, in vertebral strength test, stress in point A decreased by 7.2%, stress in point B decreased by 16.8% in single segment group, compared with that in cross-segment group, with significant difference（P 〈 0.05）. Stress in point A decreased by 13.9%, stress in point B decreased by 26.7% in single segment group, compared with that in instability group, with significant difference （ P 〈 0.05 ）. In load-strain test, stress in point A decreased by 6.9% and 13.8%, stress in point B decreased by 15.3% and 30% in single segment group, compared with those in cross-segment group and instability group,with significant difference（ P 〈 0.05 ）. Horizontal displacement decreased by 6.8% and 40% in single segment group, compared with those in cross-segment group and instability group, with significant difference （P 〈 0.05 ）. Longitudinal displacement decreased by 13% and 37% in single segment group compared with those in cross-segment group and instability group, with significant difference （P 〈 0.05）. [ Conclusion] Single segment fixation fit bio- mechanical support,with clinical application prospect.