三维打印个体化导航模板在枕骨髁螺钉固定技术中的应用研究

An individualized navigation template based on the three-dimensional printing technique: application to the occipital condyle screw insertion

目的:探讨一种基于三维打印技术制备个体化枕骨髁螺钉导航模板的可行性,并对该方法辅助置钉的准确性和安全性进行评估。方法:选取20具成人尸体的枕颈部标本,将其CT扫描数据导入Mimics软件,对枕骨至枢椎水平行选择性三维重建,观察并测量枕骨髁相关解剖结构以确定置钉参数。在计算机三维模型上虚拟枕骨髁螺钉钉道及其导向通道,设计与枕骨后部结构相贴合的阴模,将阴模与导向通道整合后利用三维打印技术成型,制作出枕骨髁模型及对应的个体化导航模板。然后导航模板辅助下分别于模型和尸体标本置入双侧枕骨髁螺钉,并通过解剖观察及CT扫描评估置钉准确性。结果:枕骨髁的大体形态及毗邻解剖结构个体差异较大,虚拟置钉后测得置钉轴位内倾角、矢状位倾角和进钉点至寰枕关节面的垂直距离分别为30.2°±6.3°、8.1°±2.6°和3.69±0.42mm。根据置钉参数设计并打印出20个枕骨髁模型及对应的个体化导航模板,在其辅助下成功置入双侧枕骨髁螺钉共40枚,置钉耗时(60.1±9.3)s。术后解剖观察及CT扫描提示所有螺钉均准确置入枕骨髁内。结论:使用Mimics软件能够根据CT扫描结果利用三维打印技术制作出个体化枕骨髁螺钉导航模板,辅助置钉准确性高,操作简单,为枕骨髁螺钉的精确置入提供了新思路。

Objectives： To investigate the feasibility of establishing an individualized navigation template for occipital condyle screws insertion by using the three-dimensional printing technique, and to evaluate the accuracy and safety of template-assisted condyle screw insertion. Methods： Twenty adult occipitoeervical specimens were selected to take a CT-scan. After importing original Dicom data into the Mimics software, 3D-models of the cranioeervical junction were created, which were used to evaluate anatomic structures related to condyle screws and define the parameters of screw placement. The screw path was determined through the guidance of canal and the cavity model of occipital bone structure, which were assembled together to generate the navigation template with a well -established screw path based on the three-dimensional printing forming technique. Anatomy study and CT-scan were taken to access the position of the screws after the insertion of bilateral condyle screws on cadaveric specimens and 3D-models. Results： Significant individual variation of the anatomical structure related to the occipital condyle screw was identified. The axial medial angle, sagittal cranial angle and the distance between entry point and atlantooccipital joint were 30.2°±6.3°, 8.1°±2.6° and 3.69±0.42mm, respectively. Forty condyle screws were implanted assisted by 20 individualized navigation templates with an average time of 60.1±9.3s. Anatomy study and CT-scan showed no intrusion of the vertebral artery, hypoglossal canal, condylar emissary canal or atlantooccipital joint. All screws were completely contained within the condyle. Conclusions： The study proves the feasibility of using the Mimics software for establishing 3D-models of the occipital condyle and related anatomy structures. The individualized navigation template, designed and generated by the three-dimensional printing technique based on established screw path parameters, is proved to be a feasible, precise and low-cost method, which can be a new alternative to conventional technique for screw placement.