Evaluation of success rate of 3d prınter navigation template in clinical use

Objective: Spondylosis and spine instability play an important role in the etiology of low back pain complaints, which are common in modern society. Indications for surgical treatment are pain, signs of root compression and increased deformity that do not respond to conservative treatment. Posterior or posterolateral fusion applications without instrumentation applied in the surgical treatment of spondylosis have been discredited due to the long-term immobilization requirement and high rate of pseudoarthrosis. Transpedicular screw fixation applications are the most appropriate internal fixation method for lumbar spinal fusion in the treatment of lumbar spondylosis. This technique provides strong vertebral segmental fixation with a high bone fusion rate. It has been observed that transpedicular screw systems provide much better segmental fixation compared to other posterior instrumentation systems such as laminar hook-rod or segmental wire-rod. Successful application of transpedicular screw systems requires a thorough knowledge of pedicular anatomy, knowledge of the biomechanical properties of instrumentation and careful surgical preparation. Complications of pedicular screw applications include inadequate instrumentation, wound infection, prolonged operation time and excessive blood loss, but the most important complication of pedicular screw application is incorrect insertion of the screw. In this case, there may be radix, dura, cauda equina or spinal cord injury. In order to minimize or eliminate this risk, the preoperative plan should be made very well and a meticulous surgery should be applied. The first and currently most common application of 3D printing to produce patient-specific devices is the production of patient-specific anatomical models, often referred to as biomodels. Biomodels can reduce the complications and potential risks for the patient by shortening the operation time. The cost-benefit analysis of biomodels shows that these can potentially reduce the cost of healthcare. The protocols to be created will help the pedicle screw to be placed easily and accurately in surgeries. Pedicle screw fixation with 3D navigation template assisted in spinal surgery is low cost and can reduce the radiation exposure of both patients and surgeons due to fluoroscopy. Our primary aim in this study is; To reveal the advantages of posterior instrumentation with 3D navigation method for the patient and the surgeon. In addition, it is aimed to detect the errors that may occur in this new technique and to show them statistically. Materials and Methods: Permissions for this study were obtained from Gaziosmanpaşa University Faculty of Medicine Dean's Office and Gaziosmanpaşa University Faculty of Medicine Dean's Office of Clinical Studies Ethics Committee. Subsequently, all patients included in the study were informed verbally and in writing about the study, and their signatures were obtained on an informed consent document regarding the use of the surgery to be performed, preoperative and postoperative imaging examinations, as well as the patient records kept. Male and female patients who were hospitalized for lumbar spondylosis between 01/03/2021 and 10/04/2021 were included in the study. A total of 10 patients who were hospitalized due to spondylosis, accepted the study, and underwent posterior instrumentation as planned were included in the study. Computed tomography (CT) images taken before the operation (preoperative) were processed with "3D Trauma" which is the associated feature of the hospital's pacs system "Sectra" and a vertebra model was created. The created model was reconfigured with the program named "Meshmixer" and the localization, angle and length data where pedicle screws should be placed were processed on the model, and a mold was created to guide the transpedicular screws during the operation. This model and mold were made to be printed on a 3D printer with the software named "Cura". The molds and models created were embodied using a 3d printer. The resulting mold was made ready by applying sterilization before the operation. During the operation, transpedicular screws were placed with the help of a 3D printer mold. After the operation (postoperative), the instrumentation performed with the CT on the patient was checked. In preoperative CT, the appropriate screw angle was calculated and recorded in axial and sagittal planes. In postoperative CT, the angle of the screw was calculated and recorded in axial and sagittal planes and the margin of error was calculated statistically by comparing with preoperative data. In the study, data such as mean, standard deviation, number and percentage were used for statistical analysis. The significance test of the difference between the two partners was used for preoperative and postoperative measurements. Statistical Package for the Social Sciences (SPSS) 20 package program was used for statistical analysis. Results: Preoperative axial and sagittal, postoperative axial and sagittal angles of the patients included in the study were evaluated. Mean and standard deviations were calculated separately for each group. When the significance test of the difference between the two partners was performed, results with a 'p' value above 0.05 were obtained for all groups. It was demonstrated statistically that there was no significant difference between preoperative and postoperative angles for each group. Preoperative axial angle mean value measured for the determined vertebral segment right side of the patients was determined as 13.330 and the standard deviation was determined as 4.630. The mean value of the postoperative axial screw angle on the same side was calculated as 14.730, and the standard deviation was calculated as 3.280. The preoperative sagittal angle mean value measured for the same vertebral segment right side was found as 4.980 and the standard deviation was found as 1.710. The mean value of the postoperative sagittal screw angle on the same side was calculated as 3.310 and the standard deviation of 2.170. Preoperative axial angle mean value measured for the left side of the same vertebral segment was determined as 11.350 and the standard deviation as 4.250. The mean value of the postoperative axial screw angle on the same side was calculated as 14.650, and the standard deviation was calculated as 5.640. The mean preoperative sagittal angle measured for the left side of the same vertebral segment was found as 5.220, and the standard deviation was found as 1.630. The mean value of the postoperative sagittal screw angle on the same side was calculated as 5,500 and the standard deviation of 2,340. It was determined that there was no statistically significant difference between the angles planned preoperatively and postoperative screw angles. Conclusion: In our study, programs named Sectra and Meshmixer were used to create a 3D navigation template. The programs we use are cost effective. During our study, in order to increase the compatibility of the 3D navigation template we produced specially for the patient, different molds were tried and the most suitable mold was reached. This mold has been matched to the posterior lumbar vertebral surface in large proportions. Thus, the probability of error in determining the screw angle has decreased considerably. The application of the 3D navigation template on patients in our study has provided great gains in terms of experience for this technique. No statistically significant difference was found between the angles where transpedicular screws were planned to be placed in preoperative CT and the angles that appeared as a result in postoperative CT. This showed that the 3D navigation template we used in our study was successful. Our study, which is an effective method, was carried out with a limited number of patients. Studies with larger patient series are needed. Keywords: 3D navigation template, instrumentation, transpedicular screw