寰椎椎弓根钉内固定通道的三维CT影像学研究

Anatomic basic study of channel of atlas pedicle screw fixation

目的利用三维影像学探讨常人寰椎椎弓根钉内固定通道的解剖学基础。方法从本院PACS系统中随机选取60例头颈部CTA枕寰枢复合体无明确异常的影像学资料,进行回顾性三维CT成像。测量相关解剖学数据,以颈椎扩孔器横截面面积（3~5 mm2）为对照,归纳出3种椎弓根类型。结果 60例头颈部CTA三维图像显示寰椎及周围结构清楚,测量出寰椎椎动脉沟底部后弓外径高度男性（4.39±1.16）mm,女性（3.84±0.84）mm,小于常规螺钉直径（3.50 mm）占27.7%;在寰椎椎弓根通道分型中,Ⅰ型68侧,占56.67%,Ⅱ型25侧,占20.83%;Ⅲ型27侧,占22.50%;皮质骨面积比例随通道面积的减小而增大,在各型椎弓根通道都在80%以上。结论寰椎椎动脉沟底部后弓外径高度是制约寰椎椎弓根钉固定的重要因素,而寰椎椎弓根骨性通道的解剖结构特点则影响置钉技术的选择;设计出适应寰椎椎动脉沟底部后弓外径高度的螺钉是非常必要的。

Objective To investigate the anatomic characteristics of the bone channel of atlas pedicle screw and collect other relative anatomic information with three-dimension imaging Methods Sixty atlas lesion free cases from patients were randomly selected,who had a computed tomography angiography(CTA) screening due to cerebral vascular diseases from PACS.The cross section area of reamer(3 to 5 mm2)served as a baseline and 60 patients were divided into three pedicle types.Results The diameter of the atlas posterior arch of the vertebral artery groove bottom in male was(4.39±1.16)mm,while in female it's(3.84±0.84)mm.The ratio of the atlas posterior arch of the vertebral artery groove bottom with a diameter less than that of normal screw(3.50 mm) was 27.7% in the whole cases studies.In the arch of the atlas channel types,typeⅠ had 68 cases(56.67%),typeⅡ 25 had cases(20.83%),typeⅢ had 27 cases(22.50%).The cortical bone area had a more than 80% ratio in all types of pedicle channel,which was increased as the atlas pedicle channel cross-sectional area decreased.Conclusion The diameter of atlas posterior arch of the vertebral artery groove bottom is an important factor which needs to be considered for the atlas pedicle screw fixation.In addition,the antonymic structure of the atlas bone of the pedicle anatomy of channel can affect the choices of the pedicle screw techniques.The design of the screw to meet the biomechanical criteria and to adapt the diameter of the bottom of the atlas posterior arch of the vertebral artery groove is undoubtedly necessary.