腰椎棘板螺钉动态内固定系统的生物力学研究

The biomechanical study research of lumbar laminar screw system

目的探讨棘板螺钉内固定系统（Laminar screw dynamic system,LS）对腰椎生物力学的影响。方法采用9具新鲜成人的尸体标本,取腰椎（L1~L5节段）作为研究对象。将标本固定于生物力学试验机。手术节段为L4-5,两个椎体植入金属标记体,记录运动范围。根据标本的先后的不同处理方法分为完整组（NS组：保留关节突及韧带）、失稳组（IS组：切除双侧黄韧带及小关节内侧1/2部分）、棘板螺钉固定组（LS组：即L4双侧下关节突内侧1/2切除,黄韧带切除＋L4、L5棘板螺钉固定）、Coflex固定组（CS组：L4双侧下关节突内侧1/2切除,黄韧带切除＋Coflex植入）和坚强固定组（PS组：L4双侧下关节突内侧1/2切除,黄韧带切除＋椎弓根螺钉植入）等5组,各在前屈、后伸、左右侧弯、左右旋转6个方向加载生理载荷,测试椎体（或椎间盘）的刚度、强度以及各个方向的运动范围。结果 LS组和CS组的椎体（或椎间盘）强度无显著差异（P〉0.05）,两者均高于IS组（P〈0.05）。LS、CS、NS组垂直位移无统计学差异（P〉0.05）。与NS相比,LS和CS组的轴向和剪切刚度无统计学差异（P〉0.05）,PS组刚度显著增高（P〈0.05）。结论棘板螺钉内固定和Coflex能够良好的恢复腰椎的即刻稳定性并保留活动度。

Objective To explore the biomechanical influence of lumbar laminar screw system on lumbar vertebrates. Methods 9 fresh cadaver specimens were obtained and the L1-5were adopt to finish the experiment. Specimens were fixed on the biomechanical machine. They were received different treatment in order of keeping all facets and ligaments（NS group）, removing the flavum ligaments and half of facet（IS group）, fixing specimens in IS group with LS（LS group）, fixing specimens in IS group with Coflex system（CS group）, fixing specimens in IS group with pedicle screw system（PS group）. With physiological load, the vertebral stiffness, strength and movements of specimens in flexion, extention, lateral flexion and rotation were tested and analyzed. Result BMD Strength in the LS and CS groups were appear no significant difference（P〈0.05）, while they were higher than that in IS group（P〈0.05）. Vertical displacement in LS, CS and NS group were not significant different（P〈0.05）. Compared with NS group,vertical and horizontal stiffness in LS and CS groups were not significantly different（P〈0.05）. The average stiffness in all other groups were lower than that in PS group（P〈0.05）. Conclusion LS and Coflex system can effectively recover the immediate stability and keep the activity of lumbar.