Abstract:

Objective To investigate the accuracy and safety of the individualized 3D print ⁃guided tem⁃ plate in the placement of atlantoaxial fracture pedicle screws. The navigation template suitable for the placement of atlantoaxial pedicle screw was designed and made by using 3D printing technology，the accuracy of the template was verified，and the deviation of screw trajectory was quantitatively analyzed. Methods Eleven patients with atlantoaxial fracture were treated in the second affiliated Hospital of Bengbu Medical College from September 2017 to June 2019. The three⁃dimensional CT data of cervical vertebrae were collected，and the three⁃dimensional bone model of cervical vertebra was reconstructed by computer Mimics software. The anatomical characteristics of atlanto⁃ axial pedicle，spinous process，lamina and lateral mass were obtained，the best trajectory of pedicle screw was sim⁃ ulated，and the reverse template was designed according to the ideal pedicle channel. The 3D printing mechanism was used to make the patient′s cervical solid model and the corresponding atlantoaxial navigation template. A total of 44 atlantoaxial pedicle screws were implanted by the same spinal surgeon using the cervical model guide plate to assist in the simulated operation. After screw placement，thin slice CT scan and Mimics reconstruction were per⁃ formed again. The accuracy of screw placement was evaluated according to the measurement of whether the screw had penetrated the pedicle cortex and the screw，and compared the head inclination angle and internal inclination angle of the actual screw track with that of the ideal screw track. Results A total of 44 atlantoaxial pedicle screws were placed in 11 cervical models. Postoperative CT scan showed that no atlantoaxial screw penetrated the pedicle cortex，and there was no significant difference in head inclination and introversion angle between ideal screw track and actual screw track（P > 0.05）. Conclusion The individualized 3D printing individualized navigation template had high accuracy and safety in auxiliary atlantoaxial fracture nail placement，which was worthy of further clinical research and application.

Key words:

atlantoaxial, pedicle screw, navigation template, 3D printing