数控机床技术在下颈椎个体化导向模板制作中的应用

目的　利用计算机辅助设计与数控机床加工技术为下颈椎椎弓根螺钉个体化导向模板提供一种新的加工方法。 方法　取1具下颈椎标本（C3~7）进行CT扫描，在Mimics14.11中重建颈椎三维数字椎骨模型，依据三维椎骨模型在Geomagic studio12软件设计椎弓根导向模板，采用数控机床技术制造出金属材质的个体化导向模板，使用个体化导向模板辅助在下颈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5个导向模板辅助钻削10个椎弓根钉道，术后CT扫描示所有钉道均位于椎弓根内。计算水平面绝对偏差值为（0.44±0.23）mm，矢状面为（0.37±0.20）mm，计算机模拟置入3.5 mm椎弓根螺钉置入椎弓根内，1级螺钉9枚，2级螺钉1枚。 结论　应用现代数字化技术，利用逆向工程原理设计并数控机床进行加工制作椎弓根螺钉导向模板，操作简单，准确性高，为下颈椎椎弓根导向模板提供了一种全新、安全的方法。

Experimental study on individual guide templates produced by CNC machine tool technology assisted pedicle screws insertion in the lower cervical spines

Objective Using of computer aided design and CNC machine tool technology for individual guide templates of lower cervical pedicle screws provides a new method for processing. Methods According to pre-operative CT scan data, 3D reconstruction models of lower cervical vertebra were obtained by Mimics; a based on the 3D model, the individual guide templates were designed and were subsequently produced by a CNC machine. The templates were used for lower cervical vertebrae screw placement in cadavers. Subsequently, CT scan was performed to evaluate the screw position. Results All 10 K-wires were inserted into the cervical pedicles. The absolute deviations were (0.44±0.23) mm in axial plane and (0.37±0.20) mm in sagittal plane. In the simulated insertion, 9 screws position were in grade 1, 1 screw was in grade 2. Conclusion Pedicle screws placement assisted by individual guide templates is highly accurate and simple. It is a new alternative to lower cervical pedicle.