螺旋CT个体化测量辅助下颈椎椎弓根置钉的实验研究

The experimental study of lower cervical transpedicular screw placement with the assistance of individualized measurement of spiral CT scan

目的:探讨螺旋CT测量辅助下颈椎椎弓根个体化置钉的准确性。方法:成人颈椎标本10具行螺旋CT扫描重建,在其多平面截面图像上设计出理想进钉路线,此路线在后方侧块上的投影点(O点)即为理想的进钉点,测量出O点与侧块外缘的距离(HO),或到横突根部的距离(HT),与侧块下缘的距离(HL),或与侧块上缘的距离(HU)。同时测量此路线与椎体中轴线的夹角(Am)以及与椎体上终板的夹角(AE);测量椎弓根峡部松质骨核心的长径(IL)与短径(IS),并测量其向内倾斜角度(f)。在标本上依据上述测量得到的数据找出椎弓根内固定的进钉点即O点,并根据测量的角度确定进钉方向后插入克氏针模拟置钉。将置钉后的标本进行CT扫描,判断其准确性。结果:共置入98枚克氏针,89枚(90.8%)完全在椎弓根内,9枚(9.2%)穿破椎弓根。结论:利用螺旋CT测量的数据辅助下颈椎椎弓根置钉有较高的准确性,但仍有一定的椎弓根穿破率。

Objective：To assess the accuracy of lower cervical transpedicular screw placement with the help of dates available from spiral CT scan.Method： 10 adult human cervical specimens were scanned with spiral CT,then the images of multiplanar reconstruction were got,and the ideal routine of screw placement was determined on the images,O point was the projection of the routine on the lateral mass（the ideal anchor point）. The following distances were defined ：HO ：distance between O point and the outer edge of the lateral mass, HT：O point to the root of the transverse process,HL：O point to the inferior edge of the lateral mass,HU：O point to the superior edge of the lateral mass;Angular measurement includes Am and AE,Am was defined as the angle between the routine and vertebral body midline,AE was the angle between the routine and the upper endplate of the vertebra.The inner height（IL） and width（IS） of the cancellous bone of the pedicle isthmus,along with the medial inclination of the isthmus were measured.Then these specimen were instrumented from C3 to C7 based on the available measurement.Computed tomography was used to assess the accuracy of screw placement.Resuit：A total of 98 pedicles were instrumented.90.8%（89 cases） of the screw trajectory were entirely within the pedicle,9.2%（9 cases） had evidence of pedicle penetration.Conclusion：On the basis of the data available,the accuracy of lower cervical transpedicular screw placement is enough,but the perforation still exist.