新型单椎单侧椎弓根导向模板辅助下颈椎椎弓根个体化置钉

Individualized unilateral navigation template assisting inferior cervical pedicle screw fixation

目的：探讨新型单椎单侧椎弓根导向模板辅助下颈椎椎弓根个体化置钉的准确性。方法对需要行颈椎后路椎弓根内固定治疗的22例下颈椎患者术前行CT扫描,根据CT扫描资料,利用逆向工程原理及快速成型技术,采用Mimics 16．0和Imageware 12．0软件,制作颈椎三维模型,并设计出个体化的新型单椎单侧椎弓根导向模板,辅助颈椎椎弓根置钉。术后复查颈椎CT评价椎弓根螺钉的位置,按照Lee et al的评定方法将螺钉在椎弓根内的位置分为4级：0级,螺钉完全位于椎弓根内；1级,穿破椎弓根的部分〈螺钉直径的25%；2级,螺钉直径的25%-50%穿破椎弓根；3级,穿破椎弓根的部分〉螺钉直径的50%。0级和1级认为置钉满意,2级和3级认为螺钉误置。结果22例均获得随访,时间6-36个月。22例患者共置入椎弓根螺钉113枚,改为侧块螺钉固定3枚。术后复查CT提示椎弓根螺钉位置107枚为0级,4枚为1级,2枚为2级。仅2例发生误置,置钉准确率达98．2%。其中1级和2级共6枚椎弓根螺钉均穿破椎弓根外侧壁,无椎弓根内侧壁及上、下壁穿破情况。对螺钉穿破外侧壁的患者行椎动脉MRA检查,未见椎动脉损伤。患者均未出现螺钉误置导致的脊髓、神经损伤并发症。结论新型单椎单侧椎弓根导向模板辅助下颈椎椎弓根个体化置钉准确性高,相关并发症少,为下颈椎椎弓根的置入提供了一种新的方法。

Objective To explore the accuracy of new navigation template for inferior cervical pedicle screw place-ment. Methods Preoperative CT scan was applied in 22 patients requiring inferior cervical pedicle screw fixation. According to CT scan data, three-dimensional cervical vertebrae models were made and the individualized unilateral navigation templates of cervical vertebral pedicle were designed by using reverse engineering and rapid prototyping de-riving from Minics 16. 0 and Imageware 12. 0 software. Cervical pedicle screws were inserted with the assistance of navigation templates. The position of screws were evaluated by postoperative CT scan, according to Lee et al criteri-on：grade 0, no perforation;grade 1, perforation less than 25%;grade 2, perforation from 25% to 50%;grade 3, perforation more than 50%. Grade 0 and 1 were regarded as accuracy and grade 2 and 3 were regarded as misplace-ment. Results All 22 cases were followed up for 6-36 months. 113 pedicle screws were inserted in total, 3 lateral mass screws were used to replace preoperative planned pedicle screws in 22 patients, including 107 screws with grade 0, 4 screws with grade 1, 2 screws with grade 2. Two screws were misplaced. The accuracy rate was 98. 2%. The 6 pedicle screws belonging to grade 1 and 2 all perforated lateral wall. No pedicle screw perforated medial, superior or inferior wall. No complications resulted from screws misplacement occurred, such as the injury of vertebral artery, spinal cord or nerve root. Conclusions The individualized unilateral navigation template assisting inferior cervical pedicle screw fixation is a new method with high accuracy and low complications.