ABSTRACT
OBJECTIVE@#To compare accuracy of anterior cervical pedicle screws between assist of rapid prototyping 3D guide plate and free-hand insertion, and evaluate the safety of two methods.@*METHODS@#Eight adult cervical cadaver specimens after formaldehyde immersion, including 4 males and 4 females, aged 32 to 65(40.3±5.6) years old. After X-ray examination to exclude bone damage and deformity, 4 of them (3D guide plate group) randomly selected were for CT scan to obtain DICOM format data, and the data was imported into Mimics software for model, designed the ideal entry point and nail path for anterior cervicaltranspedicular screw (ATPS). After obtaining the personalized guide plate of the nail channel, it was exported as STL data, and the individual guide plate was printed by rapid prototyping and 3D printing technology. In turn, with the assistance of 3D guide plates, one-to-one personalized ATPS screws were placed on the four lower cervical cadaver specimens. Another 4 (free-hand group) lower cervical cadaver specimens were implanted with ATPS screws using free-hand technique. All specimens were performed CT thin-layer scanning and three-dimensional reconstruction after operation. The Tomasino method was used to evaluate the safety of the screws on the CT cross-sectional and sagittal images, to determine whether there was a cortical puncture of the lower and inner edges of the pedicle. According to the CT rating results, gradeⅠandⅡwere safe, and grade Ⅲ- Ⅴ were dangerous.And the accuracy of screws was recorded and analyzed between two groups.@*RESULTS@#Two screws were inserted in each segment from C@*CONCLUSION@#The 3D printing rapid prototyping guide plate assisted insertion of the anterior cervical pedicle screw can significantly improve the accuracy and safety, and provide a theoretical basis for further clinical application.
Subject(s)
Adult , Aged , Female , Humans , Male , Middle Aged , Bone Plates , Cervical Vertebrae/surgery , Cross-Sectional Studies , Pedicle Screws , Printing, Three-DimensionalABSTRACT
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.