快速成型颈椎模型的精度测定及其用于术中置钉导向的可行性研究

Accuracy of rapid cervical vertebral prototyping and feasibility of its application in cervical screw placement

中文关键词:  快速成型  仿真误差  椎弓根置钉

英文关键词:Rapid prototyping  Emulate error  Ｃervical navigation

中文摘要:

  【摘要】 目的：实验测量快速成型颈椎模型的精度，并探讨其用于手术置钉导向的可行性。方法：福尔马林固定颈椎标本8具，椎板、棘突打孔后CT扫描，其DICOM格式数据通过Mimics软件转换成STL格式后用不同机型、材料、方法快速成型制作两组模型（模型组1和模型组2）。测量模型相应孔心距离，与标本孔心距离对照、统计误差，获得快速成型颈椎模型精度，并分析其误差来源。其中模型组2于C3～C7椎板孔中插入克氏针，石膏堆积在克氏针周围的椎板上制作模块，拔除克氏针，以带孔的模块腹侧面为吻合面，将模块吻合面贴附标本和模型组1相应椎板上，检查模块与椎板帖服的密合情况，并用克氏针插孔验证模块开孔与标本和模型组1相应开孔的准确性。临床应用于颈椎患者7例，将其CT数据快速成型制作模型及模块，于术中模块导向下行椎弓根置钉，术后CT验证置钉准确率。结果：标本、模型组1、模型组2三个组间的孔心距离无显著差异，模型组1与模型组2的精度误差均小于0.3mm，两组模型间三维误差无显著性差异；模块与模型组2、模型组1和标本吻合性好，孔向准确。模型、模块导向下颈椎置钉24枚，均位于椎弓根内，置钉准确率100%。结论：快速成型模型具有高精度仿真效果，可用于佐助颈椎手术置钉导向。

英文摘要:

  【Abstract】 Objective：To test the accuracy of rapid prototyping of cervical vertebrae and investigate the feasibility of its application in screw placement.Method：8 adult cervical specimens soaked with formalin，perforated in the vertebral plate and spinal process prior to CT scan were used.The CT data were converted from DICOM format into STL format by software Mimics，then different types，material and methods were used to establish 2 group models using rapid prototyping.The distance of the bores between the models and the specimens were compared and analyzed to acquire the accuracy of the cervical vertebrae model using rapid prototyping technology.In model group 2，K-wire was inserted into the vertebrae plate（levels C3-C7），stacking the gypsum around the vertebrae plate near the K-wire to manufacture templates，then then the K-wire was pulled out.Accordingly the ventral surface of the foraminiferous template was the faying surface.The faying surface of the template was sticked onto the vertebrae plate of each group 1.K-wire was used to verify the accuracy of the perforation in the templates of the specimens and models，and the CT data were acquired to manufacture models and templates for intra-operative navigation of pedicel screws placement in 7 patients.The accuracy of screw placement was evaluated after operation.Result：There was no significant difference in the distance of bores among specimens，model group 1 and 2.The precise error between model group 1 and 2 was less than 3mm.There was no significant difference in three dimensional error between 2 model groups.There was a significant consistence among the template and the model group 1 and 2. 24 screws were inserted into pedicles of the cervical spine.Under the guidance of model and template，the accuracy was 100%.Conclusion：The accuracy of rapid prototyping has high，which can be used as an intra-operative navigation for the cervical screw placement.