Mimics及颈椎模型用于下颈椎椎弓根个体化置钉的应用研究

目的利用快速成型技术及Mimics软件设计一种新的下颈椎椎弓根钉个体化置入技术,并探讨其临床应用意义。方法对16例成人下颈椎标本行CT扫描收集数据,导入Mimics软件对标本进行三维重建。利用Mimics相关功能在三维重建图像上寻找下颈椎椎弓根最佳轴线并测量椎弓根相关参数,制定椎弓根螺钉个体化置入方案。然后将三维重建图像以STL格式导入三维打印机,制作出下颈椎的实体模型,根据个体化置钉角度置入导向针。依照制定的个体化指定参数,并配合实体模型的直观指导,在标本上进行置钉。置钉后标本行CT扫描,判断置入准确性。利用上述方法对2例患者进行个体化置钉,术后通过CT扫描验证螺钉位置准确性。结果成功建立了与标本相似度极高的下颈椎三维重建图像和实物模型,通过测量结果设计了每个椎弓根的置钉参数。共在标本上置入148枚椎弓根螺钉,140枚位于椎弓根骨皮质之内,8枚稍穿破椎弓根骨皮质。对患者置入10枚椎弓根螺钉,CT示螺钉位置满意。结论用Mimics软件对下颈椎进行三维重建,制定个体化置钉参数,同时配合实物模型的直观指导,提供了一种下颈椎椎弓根钉个体化置钉的方法,利用该法能提高置钉安全性。

Individualization of lower cervical pedicle screw fixation with rapid prototyping and MIMICS software

Objective To design a new lower cervical pedicle screw placement based on Mimics software and rapid prototyping technology and evaluate its clinical value.Methods CT scanning was performed on 16 adult cadaveric cervical specimens(C3 to C7).The obtained CT data were imported into a workstation running MIMICS software to generate cervical three dimensional(3D) reconstruction images which saved as STL files.Then these STL files were used to produce cervical physical models using rapid prototyping technique.The optimal trajectory pedicle was explored and marked on 3D images using computer assistant design module of Mimics,and the related parameters of cervical pedicle were measured using measurement tools of Mimics.So the individualized surgery plan of pedicle screw fixation was determined according to the location of pedicle trajectory and parameters.The trajectory pins were drilled into physical model to supervise the entry point and orientation of pedicle screw.With the visualized guidance of physical model,pedicle screws were inserted in cadaveric specimens in strict accordance with individualized surgery plan determined previously.Pedicle screw fixation was performed in 2 patients with cervical disorders requiring instrumentation using this individualized surgery method as mentioned above.Results The cervical 3D image and physical model were found to be anatomically similar with each other and of great assistance in designing individualized surgery plan and supervising placement of pedicle screw.There were 148 pedicle screws inserted in the 16 cervical specimens.Among them,140 were inserted in the pedicle cortical,and the left 8 breached the pedicle cortical mildly.CT scanning indicated that the 10 pedicle screws were satisfyingly inserted in the 2 patients.Conclusion Combination of 3D image by Mimics and intuitive guidance of physical model by rapid prototyping technique improve the accuracy and safety of lower cervical stereotaxy.