基于三维打印成型技术制备个体化椎弓根置钉导航模板的动物实验研究

Preparation of individualized navigation templates for pedicle screw insertion in goats using a three-dimensional printing forming technique

目的探讨一种基于三维打印成型技术制备个体化椎弓根置钉导航模板的可行性，并对该方法辅助置钉的准确性进行评估。方法选取5只雄性崇明山羊，将全脊柱CT扫描数据导入Mimics软件，重建C3-6、T3-6和L3-6节段，设计与椎体后部贴合的阴模，利用三维打印技术成型，基于椎体模型直视下徒手将阴模制成带钉道的导航模板，并在其辅助下于目标椎体置入双侧椎弓根螺钉。术后再次行CT扫描评估螺钉位置。结果共制作60个导航模板，辅助置入椎弓根螺钉119枚，l枚螺钉因椎弓根发育异常而放弃置钉。CT扫描轴位图像显示114枚螺钉完全位于椎弓根内，5枚部分穿破椎弓根壁；矢状位图像提示除2枚螺钉突破椎间孔外，余钉位准确。结论基于CT图像，使用Mimics软件能够精确重建并建立椎体及其对应阴模。利用三维打印模型所设计的个体化导航模板，辅助置钉准确性高，操作简单，为脊柱后路的精确置钉提供了一种可供选择的新方法。

Objective To investigate the feasibility of preparing individualized navigation templates for pedicle screw insertion using a three-dimensional printing forming technique,and to evaluate the accuracy of template-assisted pedicle screw insertion.Methods Five male Chongming goats were selected and total spine CT-scan was performed.After the original Dicom data were imported into the Mimics software,the C3-6,T3-6and L3-6spinal column models were created to design and generate the cavity models based on a three-dimensional printing forming technique.The navigation template was created with a wellestablished pedicle screw path using a free-hand procedure,and then bilateral pedicle screw insertion was done assisted by the navigation templates.CT-scan was taken again postoperatively to access the position of the screws.Results Totally 60 navigation templates were prepared and 119 pedicle screws were implanted under the assistance of these templates,with one pedicle screw insertion failed due to a congenital deformity.CT-scan axial images indicated that 114 pedicle screws were completely contained within the pedicles,while 5screws perforating the pedicle walls.Sagittal images showed accurate screw placement except for 2screws perforating into the foramen.Conclusion The present study indicates that Mimics software is a feasible and precise method for establishing spinal column and related cavity model based on CT-scan images.Pedicle screw insertion assisted by a three-dimensional printing model is highly accurate and easy to perform,which may be a new alternative to conventional technique.