螺旋CT扫描下颈椎对下颈椎椎弓根螺钉的置入作用

Transpedicular screw placement evaluated by axial computed tomography of the cervical pedicle

目的通过测量颈椎椎弓根尺寸和进钉点进钉角度为置入椎钉提供依据。方法CT测量30例患者颈3-7,CT扫描测量颈椎根以下尺寸,椎根内径、外径、内侧皮质厚度、椎弓根轴长度和椎弓根长轴与中线的夹角。结果颈椎椎弓根平均内径为L3-3.3mm,颈椎椎弓根平均外径为4.0-7.0mm,最小的椎弓根在女性颈3椎体,最小的椎弓根外径为3.2 mm,最大椎弓根宽为C7,男性为11.3 mm,女性为7.4 mm。平均内壁皮质骨厚度为1.5-2.0 mm,平均椎弓根轴长度29.3to-33.7mm和平均椎弓根长轴与中线的夹角39.8度to 49.0度。结论颈椎椎弓根螺钉的置入应行CT测量,螺钉角度接近50度,进钉角度尽可能在侧块的外侧。

Objectives To provide a safe transpedicular screw trajectory by measuring the dimensions of the cervical pedicle and evaluating the entrance points and the insertion angles of transpodicular screws. Methods The dimensions of the podicles （C3-C27） were determined in 30 patients with cervical spinal lesions from CT images. CT images in which each podicle appeared largest were selected and the following dimensions determined：pedicle inner and outer widths,medial cortical thickness,pedicle axis length and the podicle transverse angle. Results The mean inner pedicle width ranged from 1.3 to 3.3mm,the mean outer pedicl width ranged from 4.0 to 7.0mm.The smallest pedicle Width was found at C3 among the female subjects for both inner and outer pedicles,The smallest outer podich width was 3.2mm,the largtest pedicle width was at C7 in both males （11.1mm） and females（7.4mm）.The mean medial cortical thickness ranged from 1.5 to 2.0mm. The pedicle axis length ranged from 29.3 to 33.7mm.The mean pedicle transverse angle ranged from 39.8 to 49.0 degree. Conclusions Axial CT measurements should facilitate transpodicular screw fixation in the cervical spine. We believe that the screw insertion angle should be close to 50 degrees,which is the mean podicle transverse angle from C3-C6.The entrypoint of the podicle screw should be located as laterally as possible in the posterior surface of the lateral mass.