A quantitative anatomical study of ideal insertion pathway of anterior axis pedicle screw fixation / 中华创伤杂志

ABSTRACT

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 measuredpedicle 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) mm.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 the peak of crista lambdoidalis of C2 vertebral body.However,AAPS placement should be individualized in term of its anatomy variability.