枢椎前路椎弓根螺钉理想置钉通道的定量解剖学研究

A quantitative anatomical study of ideal insertion pathway of anterior axis pedicle screw fixation

目的确定枢椎前路椎弓根螺钉（AAPS）理想置钉通道，为AAPS技术提供解剖学依据。方法征集颈椎结构正常的健康成年志愿者40名，行颈椎CT扫描。将颈椎CT数据导入Mimics软件，重建枢椎三维图像。根据中心线确定理想置钉通道。根据性别将枢椎分为男女两组，分别测量两组枢椎椎弓根左右侧椎弓根内中心线上可拟合的最小直径；钉道长度；进钉点至枢椎两侧上关节面内侧缘顶点连线的距离；进钉点至枢椎正中矢状面的距离；进钉点至“人”字嵴顶点的距离；钉道外倾角及钉道下倾角。结果左右侧及男女组间各指标差异无统计学意义（P〉0．05）。AAPS理想钉道的进钉点位于枢椎两侧上关节突上缘的连线下方（4．39±0．67）mm与正中矢状面外侧（3．95±0．44）mm交汇处；钉道长度为（34．15±2．93）mm；枢椎椎弓根内中心线上可拟合的最小直径为（7．04±0．87）mm；进钉点至枢椎“人”字嵴顶点的距离为（1．454-0．19）mm；角度为外倾（30．80±2．79）°，下倾（36．35±3．26）°。结论AAPS理想置钉通道可避开椎管、椎间孔等重要结构，在解剖上具有可行性，可以枢椎椎体前方“人”字嵴顶点作为进钉参考点。但临床上仍需强调AAPS置入的个体化操作。

Objective To explore an ideal screw insertion point and optimal trajectory for anterior axis pedicle screw （AAPS） so as to provide an anatomical basis for AAPS placement. Methods CT scan of the cervical spine was performed for 40 healthy Chinese adults. Then, the CT data were imported into the Mimics software to reconstruct the three-dimensional images of the axes. The data were divided into two groups according to the gender. The following data were measured：pedicle centerline minimal diameter on both left and right sides, pedicle axial length, the distance between entrance point and upper endplate, the distance between entrance point and median sagittal plane, the distance between entrance point and peak of crista lambdoidalis of C2 vertebral body, extraversion angle and sagittal angle. The screw fixation parameters for AAPS were measured using the Mimics software. Results There was no statistical difference between the left and right sides as well as between the genders （ P 〉 0.05 ）. The entrance point for insertion of AAPS was recommended to be on （ 4. 39±0. 67 ） mm from the upper endplate, and on （ 3.95 ± 0.44 ） mm from the median sagittal plane. The ideal pedicle axial length was （34.15 ± 2.93 ） mm, and the pedicle centerline minimal diameter was （7.04 ± 0.87 ） mm. The distance between the entrance point and the peak of crista lambdoidalis of C2 vertebral body was （ 1.45± 0. 19） ram. The ideal extraversion angle was （ 30.80 ± 2.79） °, and the ideal sagittal angle was （ 36.35 ± 3.26） . Conclusion The ideal insertion pathway of AAPS placement can avoid spinal canal, foramen intervertebrale and other important anatomical structure, which is feasible in regard of anatomy. The insertion point can refer to tile peak of erista lambdoidalis of C2 vertebral body. However, AAPS plaeemenl should be individualized in term of its anatomy variability.