Clinical Application Of A Novel 3D Printed Drill Guide Template In Atlantoaxial Pedicle Screw Placement

Part ⅠDesign of a novel 3D printed drill guide template and its clinical application in atlantoaxial pedicel screw placementObjectiveAtlantoaxial posterior pedicle screw placement has been widely used to treat atlantoaxial dislocation.However,it remains challenging to insert atlantoaxial pedicle screw precisely because of the complex anatomy.In this study,we designed a novel drill guide template with guide rods to assistatlantoaxial pedicle screw placement.Purpose of the study is to investigate the reliability of using this template with guide rods for atlantoaxial pedicle screw placement,and to compare the clinical outcomes of atlantoaxial pedicle screw placementby using the novel 3D printed template and by the conventional method.Material and MethodsFrom June 2014 to June 2016,a total of 54 patients with atlantoaxial dislocation were included in this study.There were 34 males and 20 females.The average age was 45.3±14.6 year(12～54y).All the patients were treated posterior atlantoaxial pedicle screw placement.25 patients underwent surgery using a novel 3D printed drill guide template(template group),while 29 patients underwent surgery by conventional method(conventional group).For patients in the template group,a 3D printed drill guide template with guide rods was designed.During surgery,the novel drill guide template and intraoperative fluoroscopy were used for the template group,while only intraoperative fluoroscopy was used for theconventional group.Operation time,intraoperative blood loss,frequency of fluoroscopy in surgery,screw placement accuracy,Japanese Orthopaedic Association(JOA)score of cervical neurological function,and visual analogue scale(VAS)of pain were used for comparisons between the two groups.ResultsAll the patients underwent surgery successfully.52 patients completed follow-up for more than 12 months,and the average follow-up time was 26.4 months.The template group had similar results in operation time,intraoperative blood loss,pre-and postoperative JOA scores and VAS scores,and improvement rate of JOA score with those in conventional group(p>0.05).The intraoperative fluoroscopyfrequency was significantly lower in the template group(p<0.001),and the screw placement accuracy was significantly higher in the template group than those in conventional group(p=0.045).ConclusionsIt is reliable to use the novel drill guide template with guide rods for atlantoaxial pedicle screw placement.Using this novel drill guide template can result in lower intraoperative fluoroscopyfrequency and higher screw placement accuracy than using conventional method.Part ⅡAccuracy assessment of atlantoaxial pedicle screws assisted by a novel 3D printed drill guide templateObjectiveTo investigate the reliability of using a 3D printed drill guide template for atlantoaxial pedicle screw insertion,and to assess the accuracy of pedicle screw insertion.MethodsBetween June 2014 andDecember 2016,42 cases including 24 males and 18 females with atlantoaxial dislocation in our hospital were included in this study.The average age was 43.7(range,12-57)years old.3D printed drill guides template with two guide rods were designed for every case using Mimics 17.0 and 3-matic 9.0 software before surgery.During the surgery,the 3D printed drill guide template was used for atlantoaxial pedicle screw placement.All patients underwent CT scan of cervical vertebrae postoperatively.Using the Mimics 17.0 software,pre-and postoperative 3D atlantoaxial models’positions were matched in a redefining coordinate.And then,angles and entry points of of pre-and postoperative screw trajactories were measured and compared.ResultsAll patients underwent surgeries successfully.The average operation time was 197±54min and the average blood loss was 372±118ml.After the surgery,60 pedicle screws were placed in atlas,and 84in axis.Two screws in the atlas protruded into spinal canal within 2 mm.The average transverse angles of preoperative ideal screw trajectories for C1 on the left and right were 7.91 ± 1.88 and 8.70 ± 2.03,respectively,and the actual screw trajectories were 7.68 ± 1.41 and 8.08 ± 2.01,respectively.The average sagittal angles of preoperative ideal screw trajectories for C1 on the left and right were 7.70 ±1.95 and 8.00 ± 1.30 respectively,and the actual screw trajectories were 8.69 ± 2.05 and 8.07 ± 2.27,respectively.The average transverse angle of preoperative ideal screw trajectories for C2 on the left and rightwere 23.87 ± 2.6 and 22.14 ± 2.57 respectively,and the actual screw trajectories were 24.42 ± 2.59 and 21.59 ± 3.31,respectively.The average sagittal angle of preoperative ideal screw trajectoriesfor C2 on the left and right were 25.76 ± 3.45 and 24.69 ± 2.89,and the actual screw trajectories were 25.38 ± 3.00 and 25.01 ± 3.61,respectively.No statistically significant differences in either screw angles or entry point location between the preoperative ideal and the actual screw trajectories were found(P>0.05).ConclusionIt’s reliable to use this 3D printed drill guide template to assist atlantoaxial pedicle screw placement.This method can result in high accuracy of atlantoaxial pedicle screw placement.