经口咽枢椎椎弓根逆向精确置钉的个性化组合式导航模板的研究

目的　利用CT三维重建、计算机辅助设计与快速成型技术为经口咽枢椎椎弓根逆向置钉设计制作一种新型的组合式个性化精确定位置钉的导航模板。 方法　取4具成人颈椎标本进行CT扫描，在Mimics14.11中重建寰枢椎三维模型，将该模型结合经口咽寰枢椎复位钢板（transoral atlantoaxial reduction plate, TARP）导入Solidworks 2014软件，设计经口咽枢椎椎弓根组合式个性化导航模板。采用快速成型技术制备组合式个性化导航模板，经该导航模板辅助在枢椎标本上置入椎弓根钉，根据术后CT数据评价椎弓根钉道位置。 结果　使用4个导向模板辅助置入8个枢椎椎弓根钉道，术后CT扫描计算水平面绝对偏差值为（0.85±0.70）mm，矢状面为（0.88±0.53）mm，水平面和矢状面的偏差值均无统计学差异（P>0.05）。在椎弓根螺钉钉道评价分析中，I型螺钉为7枚（87.5%），II型螺钉1枚（12.5%），所有螺钉处于可接受位置。 结论　本研究提出了一种新型组合式个性化导航模板用于辅助经口咽枢椎椎弓根螺钉准确置入，其操作简单，准确性高，为经口咽枢椎椎弓根精准置钉提供了一种全新、安全的方法。

Experimental study on the grouped individual guide template assisted C2 transoral pedicle placement

Objective　Using of 3D reconstruction, computer aided design and rapid prototyping(RP)technology to design and manufacture a novel grouped individual guide template for assisting C2 transoral pedicle placement.　Methods　After CT scanning of 4 adult cadaveric cervical specimens, 3D reconstruction models of upper cervical vertebrae were obtained by Mimics. Then 3D models of C1, C2 and the TARP were imported into Solidworks 2014 to design a grouped individual guide template for AAD. With the technology of rapid prototyping, the grouped individual guide template for AAD was manufactured. The templates were used for C2 transoral pedicle placement in cadavers. Subsequently, CT scan was performed to evaluate the screw position.　Results　All 8 K-wires were inserted into the cervical pedicles. The absolute deviations were (0.85±0.70) mm in axial plane and (0.88±0.53) mm in sagittal plane. No significant differences of the absolute deviations was observed on both the axial and sagittal planes（P>0.05）. In the classification of screw position, 7 screws position were in Type I, and 1 screw was in Type II.　Conclusion　C2 transoral pedicle placement assisted by the grouped individual guide template is highly accurate and simple. It is a new alternative to C2 transoral pedicle placement.