寰椎椎弓根螺钉置入相关参数的三维CT分析

Three dimensional CT study on relevant parameters of atlas pedicle screw insertion

背景:不同研究关于寰椎经椎弓根螺钉置入的进钉点和钉道角度数据各有不同。目的:利用CT多平面重建设计理想的进钉路径,测量寰椎椎弓根螺钉置入的相关骨性参数,评估寰椎椎弓根高度及椎动脉沟环变异对椎弓根螺钉置入的影响。方法:从影像存档与传输系统中随机选出2009-10-01/2010-06-30期间头颈联合部未见异常62例患者CT血管造影扫描资料,利用其图像数据进行后处理三维多平面重建成像,测量寰椎椎弓根最小高度、进钉点位置、钉道角度、最大进钉长度、钉道在椎弓根内的长度,同时观察寰椎沟环变异的发生率。结果与结论:男女寰椎椎弓根最小高度分别为(4.4±1.2),(3.8±0.8)mm,其中高度≥3.0mm占91%。男女进钉点位置至正中线距离分别为(21.7±1.2),(20.8±1.3)mm;钉道内倾角分别为(10.1±2.1)°,(10.3±2.6)°;最大进钉长度分别为(26.9±1.8),(26.5±1.8)mm;椎弓根钉道长度分别为(8.0±1.1),(7.9±1.2)mm。寰椎沟环变异发生率为25.8%,其中Ⅱ～Ⅳ型后环发生率为21.0%。这表明椎弓根最小高度及Ⅱ～Ⅳ型椎动脉后环变异直接影响螺钉置入;MPR成像技术能设计理想的螺钉置入方案,寰枢关节螺钉固定患者术前三维CT解剖测量是非常必要的。

BACKGROUND：As for studies on entry point and trajectory transverse angle of atlas pedicle screw insertion,different authors obtain different data.OBJECTIVE：To design an ideal route of screw insertion by CT multi-planar reconstruction （MPR）,to measure parameters related to atlas pedicle screw insertion,and to evaluate effect of the height of the atlas pedicle screw and variation of atlas ponticulus on the pedicle screw insertion.METHODS：Sixty-two subjects who were performed computed tomography angiography in head and neck without any pathology of craniocervical junction from October 1,2009 to June 30,2010 were selected from the picture archiving and communication system.Their axial images were used to reconstruct the images by MPR techniques.The parameters were obtained including the pedicleminimum height,location of optimal insertion point,trajectory transverse angle,the maximum length of the trajectory and the length of trajectory in atlas pedicle.The incidence of atlas ponticulus was analyzed.RESULTS AND CONCLUSION：Theminimum height of atlas pedicle was （3.8±0.8） mm in female and （4.4±1.2） mm in male,91.1% of the subjects were equal to or over 3.0 mm.The distance from screw insertion point to midline was （20.8±1.3） mm in female and （21.7±1.2） mm in male.The trajectory transverse angle was （10.3±2.6）° in female and （10.1±2.1） ° in male.The maximum length of the trajectory was （26.5±1.8） mm in female and （26.9±1.8） mm in male.The length of trajectory in atlas pedicle was （7.9±1.2） mm in female and （8.0±1.1） mm in male.The incidence of atlas ponticulus was 25.8%,of which typeⅡ-Ⅳ accounts for 21.0%.It is indicated that theminimum height of atlas pedicle screw and type Ⅱ-Ⅳ posterior ponticulus can directly affect the screw insertion,and MPR imaging can devise the ideal trajectory for pedicle screw insertion,which is necessary for three-dimensional CT anatomical measurement before atlatoaxial joint screw insertion.