枢椎椎弓根螺钉进钉点及植钉方式的解剖研究

ANATOMIC STUDY ON ENTRY POINT AND IMPLANT TECHNIQUE FOR C_2 PEDICLE SCREW FIXATION

目的对成人尸体枢椎干骨标本进行解剖学测量,探索一种简便、精确的植钉方法,为临床枢椎椎弓根螺钉内固定提供解剖学依据。方法取60具完整且无畸形的成人尸体枢椎干骨标本,以椎弓根内、外侧缘与侧块交界处连线的中点作纵垂线,经横突后支与下关节突外侧缘交界处作水平线,两线交点偏外1-2 mm处为进钉点,经椎弓根植钉,分别测量椎弓根高度及宽度、最大进钉长度、钉道至椎管和横突孔最短距离、进钉角度等解剖参数,评估枢椎椎弓根螺钉植钉的可行性及安全性。结果椎弓根上缘、中部、下缘宽度分别为（7.35±0.89）、（5.50±1.48）、（3.97±1.01）mm,椎弓根高度为（9.94±1.16）mm。最大进钉长度为（25.91±1.15）mm,进钉方向与冠状面夹角为（26.95±1.88）°、与矢状面夹角为（22.81±1.61）°。钉道至椎管、横突孔的最短距离分别为（2.72±0.83）mm和（1.98±0.26）mm。结论分别经椎弓根内、外侧缘与侧块的交界处,以及经横突后支与下关节突外侧缘的交界处作为枢椎椎弓根进钉点坐标的定位标志进行植钉,在解剖形态学方面是安全、可行的。

Objective To determine the entry point and screw implant technique in posterior pedicle screw fixation by anatomical measurement of adult dry samples of the axis so as to provide a accurate anatomic foundation for clinical application. Methods A total of 60 dry adult axis specimens were selected for pedicle screws fixation. The entry point was 1-2 mm lateral to the crossing point of two lines： a vertical line through the midpoint of distance from the junction of pedicle medial and lateral border to lateral mass, and a horizontal line through the junction between the lateral border of inferior articular process and the posterior branch of transverse process. The pedicle screw was inserted at the entry point. The measurement of the anatomic parameters included the height and width of pedicle, the maximum length of the screw path, the minimum distance from screw path to spinal canal and transverse foramen, and the angle of pedicle screw. The data above were provided to determine the surgical feasibility and screw safety. Results The width of upper, middle, and lower parts of the pedicle was（7.35±0.89）,（5.50±1.48）, and（3.97±1.01） mm respectively. The pedicle height was（9.94±1.16） mm and maximum length of the screw path was（25.91±1.15） mm. The angle between pedicle screw and coronal plane was（26.95±1.88）° and the angle between pedicle screw and transverse plane was（22.81±1.61）°. The minimum distance from screw path to spinal canal and transverse foramen was（2.72±0.83） mm and（1.98±0.26） mm respectively. Conclusion According to the anatomic research, a safe entry point for C2 pedicle screw fixation is determined according to the midpoint of distance from the junction of pedicle medial and lateral border to lateral mass, as well as the junction between the lateral border of inferior articular process and the posterior branch of transverse process, which is confirmed to be effectively and safely performed using the entry point and screw angle of the present study.