| BackgroundPosterior atlantoaxial pedicle screw fixation has become the "gold standard" method in treating of atlanto-axial dislocation. Compared with other fixation technologies, it has a short-segment of three-dimensional strong fixation, higher fusion rate and retained the biggest function of atlanto-axial joint mobility.Atlas has a complex structure with many important tissues such as spinal cord,vertebral artery and cervical nerve root.It’s a great risk placing the atlas pedicle screws under this circumstances. So it’s very important to design a personalized atlas pedicle screw channel to improve the safety and accuracy of the screw placement.In recent years, with the concept of "precision medical" putting forward, the computer assisted surgical (CAS) technology has palying a more and more important role in orthopedics, especially in spine.CAS is a multidisciplinary advancing technology including medical imaging, image analysis, virtual reality, remote control, surgery. By using medical image datas such as CT and MRI,CAS makes preoperative surgery designing, surgery simulation training, surgery of prediction and assessment come true.It can make the surgery more precise and safer. As the computer aided design (CAD), computer aided manufacturing (CAM),rapid prototyping (RP),3 d printing technology were applied in clinic, which enrich the connotation of CAS. We can realize the personalized treatment of surgery by using CAS.This clinical study combines surgery with CAS and 3 d printing technology according to the relevant research both at home and abroad and designs a personalized navigational drill guide template for placing atlas pedicle screw. To explore the feasibility and accuracy of personalized navigational template in atlas pedicle screw placement and compare it with free-hand pedicle screw placement in clinic. ObjectivesThis study simulates the process of atlas pedicle screw placement with Mimics and 3-matic by using the principle of personalized medication which can design an ideal point and angle for the placement of atlantoaxial pedicle screws. According to the point and angle of nailing,we can design a personalized navigational drill guide template for placing atlas pedicle screw and print the navigational drill guide template by using 3 d printing technology. To explore the feasibility and accuracy of personalized navigational template in atlas pedicle screw placement by comparing with free-hand pedicle screw placement in clinic.MethodsFrom January 2012 to June 2015,41 cases with the operation of atlanto-axial pedicle screw placement were analyzed.22 of them were used the free-hand,for group A, including 13 cases of male,9 cases of female, aged 35 to 68, the average age of 42.5 years, JOA score: 10.74±4.51.19 of them were used the personalized navigational drill guide template,for group B,including 9 cases of male,10 cases of female, aged 33 to 64, the average age of 46.1 years, JOA score:10.81±5.23.Two groups of patients were performed spiral CT scan preoperatively. By importing the CT datas into Mimics,we can reconstruct 3 d model atlas of patients. Simulating the process of placement,we design a personalized navigational drill guide template for placing atlas pedicle screw by using Mimics and 3-matic. Print out the atlas models and navigational drill guide templates by using a 3 d printer.1. Measure atlas related data of CT and 3 d printing atlas model to prove the accuracy and the feasibility of Mimics and 3 d printing.2. Group A was used the free-hand for the placement of atlas pedicle screw.Group B was used the personalized navigational drill guide template for the placement of atlas pedicle screw.The two group used the CT scan to evaluate the accuration of screws placement by the method of Kawaguchi.Result1.Atlas CT and 3 d printing atlas datas have no statistical difference by measuring.(P> 0.05).It indicates that using 3 d printer to print out the atlas model has high precision and can be applied to the clinical surgery.2.44 atlas pedicle screws were inserted in group A and 38 screws in group B.According to the standard of Kawaguchi,there were 21 screws in grade 0,17 in grade Ⅰ,4 in grade Ⅱ and 2 in grade Ⅲ of group A;there were 35 screws in grade 0 and 3 in grade Ⅰ of group B.There have a statistically significant difference in the accuracy of the placement between the two groups(P<0.01). The average bleeding loss of the patients of group A and group B were (407±116) ml and (428±104) ml,threr were no statistical difference between two groups (t P>0.05). Patients in group A of the average operation time was (175±41) min, average operation time of group B patients was(168±37) min, there were no statistical difference between them(P>0.05). The preoperative JOA score of the two group had no statistical difference (P>0.05).The postoperative JOA score of the two group had no statistical difference (P>0.05). Postoperative JOA score of gruop A was(14.31±2.79), compared with preoperative (10.74±4.51), statistically significant difference (P< 0.01).Postoperative JOA score of gruop B was(14.47+2.64), compared with preoperative (10.81+5.23), statistically significant difference (P< 0.01).Conclusion1. Making the personalized navigation template have high precision,which can apply for placement of atlas pedicle screw in clinic.2. Compared with free-hand pedicle screw placement, personalized navigational template in atlas pedicle screw placement has higher accuracy, it has a high clinical application value. |
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