术中即时三维导航辅助下轴性旋转腰椎椎弓根螺钉置入的实验研究

Study of pedicle screw placement assisted by intraoperative three-dimensional navigation in lumbar vertebrae with axial rotation

目的 探讨腰椎椎体轴性旋转时术中即时三维导航对提高椎弓根螺钉置入精确件的作用.方法 将不同轴性旋转角度（0°、5°、10°、20°）的16具相同腰椎仿真模型平均分为传统方法组与即时导航组（每一旋转角度4具）,随机用传统方法及术中即时三维导航法置入椎弓根螺钉,术后采集CT图像,重建螺钉轴线正交平面的椎弓根断层影像并应用Photeshop软件提取椎弓根外侧皮质轮廓线,通过判断钉道与椎弓根皮质间相互关系以及测量椎弓根外侧皮质缘距离螺钉轴线最短距离评价螺钉置入精确性.结果 两组置入腰椎椎弓根螺钉各80枚.传统方法组中,不同椎体轴性旋转角度的置钉精确性差异有统计学意义（P＜0.05）,随旋转角度增大,置钉精确性降低.即时导航组置钉精确性高于传统方法组（P＜0.01）;轴性旋转20°时的定性评价及轴性旋转5°、10°和20°时的定量评价,两组置钉精确性差异均有统计学意义（P＜0.05）.结论 腰椎椎体轴性旋转可降低椎弓根螺钉置入精确性.术中即时三维导航系统辅助可提高腰椎椎弓根螺钉置入精确性.

Objective To evaluate the effect of axial rotation of lumbar vertebrae on the accuracy of pedicle screw placement using the traditional method.as well as to assess the value of intraoperative three-dimensional（3D）navigation in improving the accuracy.Methods Sixteen lumbar simulation models at different degrees of axial rotation（0°,5°,10°and 20°）,with every four assigned with the same degree,were equally divided into two groups（traditional method group and intraoperative 3D navigation group）.Random placement of pedicle screws was carried out.followed by CT scan postoperatively.Then the outer pedicle cortex contours were depicted from reconstructed sectional pedicle images using Photoshop.The accuracy of pedicle screw placement was evaluated by determining the interrelationship between screw trajectory and pedicle cortex（qualitative）and measuring the shortest distance from pedicle screw axis to outer cortex of the pedicle（quantitative）.Results Eighty pedicle screws were implanted respectively in each group.In traditional method group,statistical difference existed in the accuracy of pedicle screw placement at different axial rotational degrees（P＜0.05）. With degrees increasing,the accuracy declined.The accuracy of intraoperative 3 D navigation group was higher than traditional method group in vertebrae with axial rotation（P＜0.01）.In qualitative evaluation,the accuracy of the two methods had statistical difference when the degree was 20°,and in quantitative evaluation,statistical difference existed in 5°,10°and 20°of vertebral axisl rotation.Conciusions Screw malposition can be caused by vertebral axial rotation in lumbar spine using traditional method.Accuracy of pedicle screw placement declines with the increase of axial rotational degrees.However,the accuracy can be improved by using intraoperative 3D navigation.