Analysis on accuracy of advanced 3D printing navigation template in assisting the placement of atlanto-axial vertebral pedicle screw

English Keywords:Atlanto-axial vertebral body  Advanced navigation template  3D printing  Deviation

English Abstract:

  【Abstract】 Objectives: To explore the accuracy of advanced 3D printing navigation template in assisting the placement of atlanto-axial vertebral pedicle screw. Methods: 17 patients who underwent pedicle screw placement of atlanto-axial vertebral were selected from our hospital between June 2015 and December 2016, including 11 males and 6 females, aging from 25 to 56 years(43.3±8.7 years). 13 patients had atlanto-axial vertebral fracture and dislocation while 4 cases had atlanto-axial vertebral deformity. Atlanto-axial CT data of patients were input into Mimics17.0 to generate a 3D model of the target vertebral body. The cylinder with the diameter of 3.5mm was used for simulation of screws in the computer-aided design software to make preliminary simulation of pedicle screw placement parallel to the direction of pedicle screw. The position relation between the screw channels and the screw channel was carefully adjusted to ensure the pedicle bone cortex was not broken through by the screw channel. The benchmark was moved parallelly about 10mm towards the inside relatively to the screw hole. The guide plate file was imported into the Forml+3D printer to print the atlanto-axial pedicle screw guide plate. The guide plate was disinfected with ethylene oxide and encapsulated for subsequent use. The surgical operations were simulated preoperatively in the previously 3D-printed model,the scheme was confirmed by in vitro test before the advanced navigation template disinfected, sterilized and applied to clinical. Advanced 3D printing template was closely adhered to the atlanto-axial vertebral body during operation. The surgeon drilled out the screw channel through the guiding channel by drill with pole as the reference, and the guiding plate was removed, and pedicle screw was placed along the screw channel. Results: The operation time was 106±11min and the intraoperative blood loss was 220±73ml. A total of 68 cervical pedicle root screws were placed, including 34 cases in atlas and 34 cases in axis. There were no statistically significant differences between preoperative and postoperative pre-designed nailing points, the inclination angle and head tilt angle(P>0.05). Postoperative Kawaguchi scale showed level 0 accounting in 97.06%(66/68), level Ⅰ in 2.94%(2/68), level Ⅱ and Ⅲ in 0, and two screws were broke through bone cortex. Conclusions: By using the advanced 3D printing navigation template auxiliary atlanto-axial vertebral pedicle nailing guide, alignment with the preoperative default best nail can be improved to exact match preoperative plan, the accuracy of clinical surgery nailing can be improved to reduce the deviation.