Safety and feasibility of a new 3D printing template designed for bilateral anterior cervical transpedicular screws placements / 中国组织工程研究

ABSTRACT

BACKGROUND: Anterior cervical transpedicular screws placement technique provides nice mechanical stability and is of very promising application prospects. However, the technology is difficult to operate and has a high risk, and has not been widely used. OBJECTIVE: To design a new three-dimensional (3D) printing template for bilateral anterior cervical transpedicular screws placements and assess its feasibility and safety in anterior cervical pedicle screw placement. METHODS: Six cadaveric cervical specimens, including three males and three females, were used in this experiment. Data of thin layer CT scanning of the specimens were saved in DICOM format and then imported into Mimics 17.0 software. Following 3D reconstructions of the cervical spine, guiding holes for C3-C7 bilateral anterior cervical transpedicular screws trajectories were designed; pedestals for the guiding holes were then designed via reversely thickening the bony structure of the anterior and 1/2 superior-anterior surface of vertebral body, and 1/2 anterior joint surface of bilateral processus uncinatus. Practical objects of the templates were obtained via 3D printing and were then used for guiding bilateral anterior cervical transpedicular screws replacements from C3 to C7. CT scanning was conducted again and the accuracy of anterior cervical transpedicular screws replacements was evaluated from sectional CT images. The difference of deviational angles on axial plane (α1, α2) and sagittal plane (β1, β2) between real and simulated trajectories were compared in Mimics 17.0 software. RESULTS AND CONCLUSION: (1) A total of 60 anterior cervical transpedicular screws were successfully inserted; 57 screws were completely located in pedicles and were judged as grade 0, representing an accuracy of 95.0%. The other three anterior cervical transpedicular screws perforated from pedicles, including grade 1 perforation in two screws (3.3%) and grade 2 perforation in one screw (1.7%). (2) By comparing real and simulated trajectories, the medical and lateral deviational angles were (0.867±0.787)° and (0.783±0.792)°, respectively (P > 0.05); the cephalad and caudal deviational angles were (1.362±1.380)° and (1.314±1.300)°, respectively (P > 0.05). (3) With the help of the 3D printing template designed in this study, bilateral anterior cervical transpedicular screws replacements could be smoothly carried out at high inserting safety.