X线分步监测胸腰椎椎弓根螺钉植入的实验研究

Placement of pedicle screws undex X-ray fluoroscopy step by step in cadaveric thoracolumbar spine

[目的]探讨X线分步监测胸腰椎椎弓根螺钉准确置入的可行性。[方法]选8具T9～L5脊柱标本，随机分A、B两组，每组4具。A组按X线分步监测方法置入椎弓根螺钉。CT扫描测量椎弓根一半长、全长及螺钉通道长度和椎弓根e角及f角。当导针进至深度为椎弓根一半时，标准正位片导针远端到达椎弓根投影中线为符合标准；当导针进至深度为椎弓根全长时，腰椎到达椎弓根投影3／4处为符合标准，而胸椎到达椎弓根投影的1／2与3／4的中线处为符合标准；导针进入椎体，调整X线机臂，侧位片观察导针深度及f角。按照导针轨道植入椎弓根螺钉。B组为对照组，按传统X线监测方法置入椎弓根螺钉。通过观察两组螺钉的位置，评估A组方法的准确性。[结果]A组植入螺钉72枚：68枚位于椎弓根内，左右螺钉基本对称；4枚穿破椎弓根，穿破率为5．56％。B组亦为72枚：53枚位于椎弓根内；19枚穿破椎弓根，穿破率为26．38％。A组优于B组（P〈0．001）。[结论]X线分步监测胸腰椎椎弓根螺钉的置入，可克服传统X线平片的局限性及减少置钉过程中的人为因素干扰，在一定程度上可使两侧椎弓根螺钉对称植入，提高了螺钉置入的准确性。

[ Objective] To investigate the feasibility of the placement of pedicle screws in the thoracolumbar vertebrae under X- ray fluoroscopy step by step. [ Method] Eight human cadaveric thoracolumbar spines （T9 ～L5 ） were selected and classi- fied into group A and group B randomly, each having 4 specimens. Pedicle screws in group A were placed under X -ray fluoroscopy step by step. CT scanned the specimens of group A and measured the half pedicle length, full pedicle length and the pedicle screw passage length. The ＂e＂ angle and ＂f＂ angle of pedicle were measured on CT images. When the guide wire was pricked to the -half of pedicle length, the wire tip was located at the middle line of the pedicle projection in the standard posterior - anterior image. When the wire was pricked to the full pedicle length in lumbar vertebrae, its tip was located at 3/4 line of the pedicle projection in the standard posterior-anterior image. When the wire was pricked to the full pedicle length in thoracic vertebrae, its tip was located at between 1/2 line and 3/4 line of the pedicle projection. When the wire was pricked into vertebrae, the depth of the wire and the ＂e＂ angle were noted in standard lateral image. Pedicle screws were placed by the track of the guide wire. Pedicle screws in group B were placed by traditional technique. The accuracy and feasibility of the method under X - ray fluoroscopy step by step were evaluated by observation of the position of the pedicle screws in group A and group B. [ Result] Four of 72 （5.56%） pedicle screws were found to have perforated the pedicle wall in group A, and 19 of 72 （26. 38% ） pedicle screws perforated the pedicle wall in group B. The result of group A was superior to that of group B （ P 〈0. 001 ） . [ Conclusion] The method under X - ray fluoroscopy step by step can improve the accuracy and quality of placement of pedicle screws, and to some degree it can make bilateral pedicle screws place symmetrically.