Abstract
ObjectiveTo design and evaluate the accuracy of a novel navigation template suitable for posterior cervical screw placement surgery by using 3D printing technology to improve the existing guiding template design.MethodsThe researchers (including spine surgeons and technicians) used CT to perform thin-slice scanning on 12 cases of normal upper cervical vertebral specimens and defined the screw channels that were completely located in the pedicle without penetrating the cortex as ideal screw channels, then designed the ideal channel of the upper cervical vertebral (atlantoaxial) pedicle screw by computer software which was regarded as the preset values, and recorded the screw entrance point, transverse angle and sagittal angle of the ideal channel. Then, researchers designed the novel navigation templates for placement pedicle screw according to the ideal screw channel preset values and manufactured them with one for every single vertebra by 3D printer. A senior spine surgeon performed the posterior surgery to implant pedicle screw on the specimens by the novel navigation templates, then performed CT thin-slice scanning on the specimens again after removing the screws, and reconstructed the actual screws channel by computer software, recorded the screw entrance point, transverse angle and sagittal angle of the actual channels which were defined as the actual values and evaluated them according to Kawaguchi’s pedicle screw evaluation standard finally. The differences between the preoperative preset values of ideal screw channel and the postoperative actual values of actual screw channel were compared by a nonparametric paired rank test.Results48 screws were placed on 12 cases of upper cervical vertebral specimens in total. It showed that the grade 0, I, II, III channels in this study were 47, 1, 0, 0, respectively. The grade 0 channels accounted for 97.92% of the total number of channels. There was no significant difference with regard to the screw entrance point, the transverse angle, and the sagittal angle between the preoperative preset values of ideal screw channels and the postoperative actual values of actual screw channels.ConclusionTo implant pedicle screw assisted with the novel individually navigation template designed by 3D printed in the posterior cervical surgery can improve accuracy of pedicle screw placement and safety of the surgery.
Highlights
Posterior placement of pedicle screw fixation is an important treatment strategy for some upper cervical traumas and diseases, such as fractures, joint dislocation complicated with neurological symptoms
A senior spine surgeon performed the posterior surgery to implant pedicle screw on the specimens by the novel navigation templates, performed CT thin-slice scanning on the specimens again after removing the screws, and reconstructed the actual screws channel by computer software, recorded the screw entrance point, transverse angle and sagittal angle of the actual channels which were defined as the actual values and evaluated them according to Kawaguchi’s pedicle screw evaluation standard
48 screws were placed on 12 cases of upper cervical vertebral specimens in total
Summary
Posterior placement of pedicle screw fixation is an important treatment strategy for some upper cervical traumas and diseases, such as fractures, joint dislocation complicated with neurological symptoms. To place the pedicle screw accurately and successfully is the key to the success of the operation. The application for posterior placement of pedicle screw fixation is confined by the high risk of vascular and nerve damage due to the complex adjacent structure of the atlantoaxial spine. With the application of additive manufacturing (3D printing) technology in the medical field, the placement of pedicle screw assisted by 3D printing navigation templates have been gradually applied to spinal surgery because of its high accuracy [1,2,3]. The new navigation template removed the guiding channel of the original guiding template and retained only the screw hole. This research evaluated the new navigation template accuracy in the auxiliary screws placement to ensure its effectiveness
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