[The effect of axis pedicle and intra-axial vertebral artery on C 2 pedicle screw placement].

To investigate the influence of axis pedicle and intra-axial vertebral artery (IAVA) alignment on C 2 pedicle screw placement by measuring the data of head and neck CT angiography.The axis pedicle diameter (D), isthmus height (H), isthmus thickness (T), and IAVA alignment types were measured in 116 patients (232 sides) who underwent head and neck CT angiography examinations between January 2020 and June 2020. Defined the IAVA offset direction by referencing the vertical line through the center of C 3 transverse foramen on the coronal scan, it was divided into lateral (L), neutral (N), and medial (M). Defined the IAVA high-riding degree by referencing the horizontal line through the outlet of the C 2 transverse foramen, it was divided into below (B), within (W), and above (A). The rate of pedicle stenosis, high-riding vertebral artery, and different IAVA types were calculated, and their relationships were analysed. Simulative C 2 pedicle screws were implanted by Mimics 19.0 software, and the interrelation among the rates of pedicle stenosis, high-riding vertebral artery, IAVA types, and vertebral artery injury were analyzed.The rate of C 2 pedicle stenosis was 33.6% (78/232), and the rate of high-riding vertebral artery was 35.3% (82/232). According to the offset direction and the degree of riding, IAVA was divided into 9 types, among which the N-W type (29.3%) was the most, followed by the L-W type (19.0%) and the L-B type (12.9%), accounting for 60.9%. The vertebral artery injury rate of simulative implanted C 2 pedicle screws was 35.3% (82/232). The vertebral artery injury rate in patients with pedicle stenosis and high-riding vertebral artery was significantly higher than that who were not ( P<0.001). The rate of pedicle stenosis, high-riding vertebral artery, and vertebral artery injury were significantly different among IAVA types ( P<0.001), and M-A type was the most common.Vertebral artery injury is more common in pedicle stenosis and/or high-riding vertebral artery and/or IAVA M-A type. Preoperative head and neck CT angiography examination has clinical guiding significance.通过对头颈部CT血管造影检查的原始数据进行测量，了解枢椎椎弓根和枢椎段椎动脉（intra-axial vertebral artery，IAVA）走行对C 2椎弓根螺钉植入的影响。.纳入2020年1月—6月116例（232侧）行头颈部CT血管造影检查的患者，测量枢椎椎弓根参数，包括椎弓根直径（D）、椎弓峡部高度（H）、峡部厚度（T）。以通过冠状位C 3横突孔中心的垂线为参考线，定义IAVA偏移方向，将其分为外侧偏移（L）、垂直进入（N）和内侧偏移（M）；以通过冠状位C 2横突孔出口的水平线为参考线，定义IAVA骑跨程度， 将其分为横突孔下方（B）、两者之间（W）和上方（A）。计算椎弓根狭窄、椎动脉高跨的发生率和不同IAVA走行类型的占比及其相互关系；通过Mimics 19.0软件模拟C 2椎弓根螺钉植入，分析椎弓根狭窄、椎动脉高跨、IAVA分型及椎动脉损伤之间的相互关系。.枢椎椎弓根狭窄发生率为33.6%（78/232），椎动脉高跨发生率为35.3%（82/232）。根据偏移方向和骑跨程度将IAVA走行分为9型，其中N-W型（29.3%）最多，其次为L-W型（19.0%）和L-B型（12.9%），共占60.9%。模拟C 2椎弓根螺钉植入椎动脉损伤发生率为35.3%（82/232）。椎弓根狭窄和椎动脉高跨者模拟C 2椎弓根螺钉植钉，椎动脉损伤率均高于无椎弓根狭窄和无椎动脉高跨者（ P<0.001）。椎弓根狭窄、椎动脉高跨及椎动脉损伤在IAVA各型中发生率差异均有统计学意义（ P<0.001），均以M-A型最多。.椎动脉损伤多发于椎弓根狭窄和/或椎动脉高跨和/或IAVA M-A型患者中；术前头颈部CT血管造影检查具有临床指导意义。.