枢椎前后路三种螺钉内固定的安全性比较*

目的 观察计算机辅助枢椎前路椎弓根螺钉（AAPS）置钉优势，并测量AAPS、椎弓根螺钉及椎体螺钉（VBS）的最大拔出力，为临床手术操作选取适当的内固定方式，提供生物力学理论依据。方法 从2019年10月至2021年1月，收集人体实体颈椎防腐标本16例，除去畸形标本1例。剩余标本，包括男10例，女5例，行CT扫描后将数据导入Mimics软件，形成三维重建图并观察。参考Kolle法，在每节枢椎上分别采用前路椎弓根螺钉、后路椎弓根螺钉、前路椎体螺钉三种形式固定方法。在生物力学试验机上测试每种固定方式的最大拔出力。结果 Mimics软件中的三维重建图，可以从任意视角直接观察并了解结构状况。前路椎弓根螺钉最大轴向拔出力平均为（635.95±220.35）N，后路椎弓根螺钉组的最大轴向拔出力平均为（772.95±230.55）N，VBS组螺钉的最大轴向拔出力平均为（451.45±181.13）N。采用配对样本t检验，两两比较AAPS组与后路椎弓根钉组，以及AAPS组与VBS组测值。P值均<0.05，差异有统计学意义。这显示在单皮质固定的条件下，椎弓根螺钉的置钉拔出力大于前路椎弓根螺钉（AAPS），AAPS置钉拔出力大于VBS置钉法。结论 计算机辅助有利于了解枢椎结构特点，便于个体化的AAPS置钉操作，AAPS钉道固定性能良好，有较明显生物力学优势，可作为手术内固定选择的较理想方式。

Safety comparison of three kinds of axial anterior and posterior screw fixation

Objective To observe the advantages of computer-assisted anterior axis pedicle screw (AAPS) placement, and to measure the maximum pullout force of AAPS, pedicle screw and vertebral body screw (VBS), and to provide biomechanical theoretical basis for selecting appropriate internal fixation type during clinical operations. Methods From October 2019 to January 2021, 16 antiseptic specimens of human cervical vertebrae were collected. There was 1 abnormal specimen. The remaining 15 specimens were from 10 males and 5 females. After CT scanning, the data were imported into Mimics software to form a three-dimensional reconstruction image and observed. Refer to Kolle method, anterior pedicle screw, posterior pedicle screw and anterior vertebral body screw were used to fix each axis. The maximum pullout force of each fixation method was tested on a biomechanical testing machine. Results The three-dimensional reconstruction image in Mimics software could directly observe and understand the structure from any perspective. The maximum axial pullout force of AAPS group was (635.95±220.35) N, the maximum axial pullout force of the posterior pedicle screw group was (772.95±230.55) N, and the maximum axial pullout force of the VBS group was (451.45±181.13) N. Using paired sample t test, the maximum axial pullout force of the AAPS group and the posterior pedicle screw group, as well as the AAPS group and the VBS group, were statistically different (P<0.05). It was shown that under monocortical fixation, the pullout force of posterior pedicle screw was larger than that of AAPS, and that of AAPS was larger than that of VBS. Conclusion It is helpful to understand the structural characteristics of the axis and to individualize the operation of AAPS. AAPS has good fixation performance and obvious biomechanical advantages. It can be used as an ideal method for surgical internal fixation.