Mimics及快速成型技术在寰枢椎椎弓根个体化置钉中的应用

Application of Mimics and rapid prototyping in atlantoaxial pedicle placement

目的 利用三维重建软件Mimics及快速成型技术设计一种寰枢椎椎弓根钉个体化置入技术. 方法用Mimics软件对CT扫描的20例成人寰枢椎标本进行三维重建,并测量重建图像的椎弓根参数.利用快速成型技术制作寰枢椎实物模型,测量模型椎弓根参数.测量寰枢椎标本椎弓根参数.对重建图像、实物模型和寰枢椎标本的椎弓根参数行统计学分析,验证重建图像的精确性.在Mimics中寻找三维重建图像椎弓根最佳钉道,制订个体化置钉参数并模拟置钉,根据这个参数和在实物模型直观指导下在寰枢椎标本上置钉.置钉后行CT扫描,判断置钉准确性. 结果寰枢椎重建图像和实物模型与标本椎弓根参数差异无统计学意义,能准确反映寰枢椎解剖结构.用上述方法,4例寰枢椎标本共16侧椎弓根行置钉术,术后CT扫描显示一侧寰椎椎弓根螺钉稍穿破椎动脉孔内侧骨皮质,其余螺钉均未穿破椎弓根骨皮质. 结论用Mimics软件对寰枢椎进行三维重建,制订个体化置钉参数,同时配合实物模型的直观指导,提供了一种寰枢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.

Objective To develop and validate a novel method of atlantoaxial pedicle screw placement by using three-dimensional reconstruction software Mimics and rapid prototyping. Methods Three-dimensional reconstruction of 20 CT scanned cadaver atlantoaxial specimens was performed by using Mimics and the parameters of the pedicles were measured. Then, physical model of the pedicles was manufactured by using rapid prototyping and the parameters of the cadaver pedicles were measured. The parameters of the atlantoaxial pedicle were directly measured. All the data were analyzed statistically to verify the accuracy of the reconstructed images and physical models. The optimal pedicle channel was found to design individual fixation parameters, based on which fixation of cadaver specimens was performed under direct guidance of physical model. The accuracy of fixation was assessed by CT scanning. Results There was no statistical difference in parameters of the reconstructed images, the physical model and the specimens, which could reflect accurate atlantoaxial anatomy. Postoperative CT scanning showed that the pedicle screws were inserted successfully in 16 sides of four specimens, except for one screw wearing medial bone cortex of the atlas artery. Conclusions Three-dimensional reconstruction of the atlantoaxial specimens by using Mimics and physical models made by rapid prototyping technology facilitate atlantoaxial pedicle screw placement and can enhance the accuracy of screw fixation.