两种不同椎弓根螺钉内固定术式对腰椎稳定性影响的生物力学对比研究

目的　通过腰椎双侧椎弓根螺钉内固定与单侧椎弓根螺钉结合对侧关节突螺钉固定两种不同内固定生物力学对比，为临床在腰椎内固定手术术式提供支持。 方法　采用4具新鲜人体标本的L4、5脊柱功能单元，在生物力学试验机上分别测量每具标本手术前、双侧椎弓根螺钉固定后、单侧椎弓根螺钉固定结合对侧关节突螺钉固定后，在前屈、后伸、左右旋转及左右侧弯状态下的活动范围（range of motion, ROM）。 结果　双侧椎弓根螺钉与单侧椎弓根螺钉结合对侧关节突螺钉两种内固定方式的6个方向的活动范围均小于术前，差异具有统计学意义（P <0.05）。与双侧椎弓根螺钉固定相比，单侧椎弓根螺钉结合对侧关节突螺钉在前屈、后伸、左侧（关节突螺钉侧）弯、右侧(椎弓根螺钉侧)旋状态下的活动范围差异无统计学意义（P >0.05），在右侧弯及左侧旋状态下的活动范围差异具有统计学意义（P <0.05）。 结论　两种不同内固定方式均可明显增强腰椎功能单元稳定性，其中，单侧椎弓根螺钉结合对侧关节突螺钉固定相比较于双侧椎弓根螺钉固定，在左旋（关节突螺钉侧）及右侧弯（椎弓根螺钉侧）活动状态下略差。

A biomechanical comparison of influence of lumbarstability by different pedicle screws fixation

Objective　To analyze and evaluate the impact on biomechanical stability between the bilateral pedicle screws fixation and the one side pedicle screw combined transfaect screw in the opposite side internal fixation, so as to provide theoretical basis in clinics to select different fixation method.　Method　 Ten lumbar samples (L4-5 functional spinal units)of fresh corpses were tested. The range of motion(ROM) of these lumbar samples were tested by experimental machine under flexion, extension, right and left lateral bending, right and left rotating state before and after different fixations.　Results 　All of the six ROMs of bilateral pedicle screws fixation and zygopophysis screw with single pedicle screw fixation were reduced compared to preoperativestate, and the difference were statistically significant（P<0.05）.Compared with the bilateral pedicle screws fixation, the differences were statistically significant under left lateral rotating and right bending（P<0.05）and not statistically significant under flexion, extension, left(transfaect screw side) lateral bending, right(pedicle screw side) rotating state.　Conclusion　Both of bilateral pedicle screws fixation and one side pedicle screw combined transfaect screw in the opposite side internal fixation could add to the biomechanic stability obviously. Compared with the bilateral pedicle screws fixation, the biomechanic stability of one side pedicle screw combined transfaect screw in the opposite side internal fixation is inferior under left lateral rotating and right bending.