Study Of Lumbar Pedicle Screws Accurate Placement Assisted By 3D Printing Navigation Modules

BackgroundWith the development of modern industry and transportation, traffic accidents and hurt patients become more and more. They are the most major pathogenic factors of common traumatic lumbar fracture. Lumbar spinal pedicle screws internal fixation system can effectively realize lumbar three columns fixation, strengthen the support of the spine and the torsion stiffness, and it has good biomechanical performance. Therefore, it was widely used in the related disorders of the lumbar spine in clinical, appreciated by doctors and patients and obtained good clinical therapeutic effect.Lumbar spinal pedicle screws internal fixation system has experienced a long stage of development. Early spinal posterior surgery used spinal steel plate as a means of internal fixation.It only fixed spinal posterior column, which cannot be treated in the medial column and anterior column spinal fractures. And for sudden deformity after fracture of corrective action, the clinical treatment effect is poor, so, doctors now rarely used spine plate internal fixation for treatment. In 1948, King invented one kind of screw, arrived in pedicle by articular process developed by fixed between the articular process to promote spinal fusion, but it was unsuccessful. In 1959, Boucher with long arrived in vertebral body through pedicle screw, applied to the lumbosacral vertebral fusion and internal fixation surgery, has obtained the good clinical therapeutic effect. In 1963, Roy Camille first developed a complete pedicle screw steel, used for the treatment of unstable thoracolumbar fractures. In 1986, after repeated trials, Roy Camille constantly improved the pedicle screws, then reported that the application of pedicle technology in the treatment of spinal fractures has obtained the good effect and confirmed that the new technology, compared with traditional method, can provide more secure, strong and solid short segmental spinal internal fixation. The clinical treatment effect is pretty good. In 1997, the FDA approves this method for the feasible spinal posterior fixation method. Since then, the pedicle internal fixation technology was rapid development and gradually formed plate internal fixation system represented by Roy Camille and Steflee steel and AO screw internal fixation system.Common lumbar pedicle screws implantation methods mainly include the following kinds:anatomical mark point method, X-ray fluoroscopy auxiliary method, computer aided navigation method, robot and individualized lumbar pedicle screws navigation template method. Various methods of pedicle screws inserted have different advantages and disadvantages in clinical. Anatomical mark point method: The anchor point and orientation of the screws mainly rely on the experience of performer’s judge. Performer using pedicle probe for detection nail channel to ensure accuracy of pedicle screw implantation. It was reported that the pedicle cortical broken rate is 0～17% by application of various anatomical mark point method. X-ray fluoroscopy auxiliary method:intraoperative using auxiliary equipment such as C-arm help implant lumbar pedicle screws, which use X-ray equipment for many times that prolong operation time of the procedure and increase patient and performer radiation hurt that add surgery damage in patients. Sagi report that the accuracy of X-ray perspective auxiliary implanted pedicle screws was 73%.Thus, the accuracy of pedicle screw implantation by X-ray fluoroscopy auxiliary method was no significant improvement. Computer aided navigation method: by means of computer aided navigation equipment can obviously improve the accuracy of the lumbar pedicle screw implantation, but computer navigation equipment is very expensive and complex operation steps need a long time to accumulation of experience. So, it is not easy to promote to basic-level hospital. In addition, other factors may affect the accuracy of navigation such as changing intraoperative posture. Robot method:the accuracy is high by robot assisted lumbar pedicle screw implantation, but the current robot equipment is too expensive to industrialize. It is not comprehensive promotion. Digital navigation template:through computer software to digital design navigation module and using 3D printers to create navigation module and lumbar entity model. Doctors may conduct preoperative simulation operation, which is help for enhance operation skill and develop the way of thinking. Consequently, it is helpful for doctors to design optimal operation plan, following the principle of the individualized lumbar pedicle screw implantation, which greatly reduce the possibility of intraoperative spinal cord, nerve and blood vessel damage as well as improve the accuracy of the screw implanted. At the same time, it can shorten the operation time, avoid too much X-ray radiation, easy operation procedure. So, it has good clinical application prospect. But the existing navigation templates are difficult to build. They need long time and high price. Consequently, it is not easy to promote to the basic-level hospitals.In recent years, with the progress of science and technology,3D printing technology is developing rapidly.3D printer can print out the 3D model of organs or tissues. Consequently, these organs and tissues can highlight details of the internal structure truly, which make the medical knowledge become more obvious. At the same time, through print out 3D entity models, it can intuitively show the patient’s disease status. So, doctors can understand detail of the patient’s condition better, especially for complex fracture or deformity.3D entity model provide medical image data and specific anatomical information, realizing virtual to real, from two-dimensional to three-dimensional, from planar to three-dimensional. Surgery can be directly simulated on the 3D print models, which enhance the development of mentality and skill promotion to ensure the success of the actual operation. Therefore, for clinical diagnosis and treatment of disease,3D printing provides personalized and accurate new ideas and new methods. Based on digital design and 3D printing technology, individualized lumbar pedicle screws navigation module entity can exactly match patients’bone. The individualized navigation module has advantages such as safe, accurate and easy to use. In addition, it can effectively reduce the radiation exposure of doctors and patients in the surgery.Above all, for clinical doctors’ diagnose and treat disease,3D printing individualized navigation module provides a new thought and method, which will promote individual medical progress. However, in order to promote the development of the lumbar pedicle screw implantation surgery, we remain to discuss further in the following aspects:simpler digital design, more convenient operation, lower technical requirements for operation personnel experience, higher accuracy of screws insertion, shorten the operation time, decrease intraoperative X-ray damage, etc. In order to achieve the best lumbar pedicle screws implantation methods,3D printing technology is a feasible way.Experimental study of lumbar pedicle screws accurate placement assisted by 3D printing navigation modulesObjectiveThrough digital design individualized lumbar pedicle screws navigation module in computer software Mimics 14.0, then using 3D printing technology create individualized lumbar pedicle screws navigation module and lumbar entity, we use the navigation module on the 3D printing lumbar to simulate screws implanted test so as to verify the feasibility and accuracy of the navigation module. Finally, realizing individualized minimally invasive lumbar pedicle screws accurate placement.MethodsUsing software Mimics 14.0 to reconstruct adult virtual lumbar (L1-L5) 3D models, we remove other organizational structure that has nothing to do with pedicle screws inserted in order to avoid the impact of the designers vision and operating, just retain navigation module of digital design and individualized lumbar pedicle screws related to the lumbar spine. First of all, we digitize design the navigation bar, selecting the center of the lumbar spine herringbone crest for lumbar pedicle screws anchor point, modifying the positions of the navigation bar to make it through the pedicle center. Consequently, the direction and position of the navigation bar is the virtual direction and position of the nail. Based on the navigation bar, we began to design individualized digital lumbar pedicle screws navigation module. The precursor of navigation module fit closely to the lumbar herringbone crest surface. Then, we use the "Boolean operation" to minus the lumbar spine and navigation bar in order to get a virtual individual lumbar pedicle screws navigation module. Then, we import the virtual navigation module and individualized lumbar pedicle screws lumbar data into a 3D printer software MakerWare to adjust the position of navigation module and lumbar. Meanwhile, printing properties have been set and then we through 3D printer to create individualized lumbar pedicle screws navigation module and 3D lumbar spine specimen entities. After that, we put into appropriate size lumbar pedicle screws assisted by individual lumbar pedicle screws navigation module in 3D lumbar spine specimen entities. Then, we observe anchor points, direction and position of the lumbar pedicle screws. Meanwhile, we compare virtual pedicle screw implantation scheme in the Mimics 14.0 with actual pedicle screws implantation scheme to test the consistency of the actual and virtual nailing. Finally, we observe whether lumbar pedicle screws wear out lumbar pedicle cortex and evaluate the efficacy of the implantation of lumbar pedicle screws.Results(1) Through digital design and 3D printing technology, we create 228 individual lumbar pedicle screws navigation modules in total. Then we implant 228 lumbar pedicle screws by 228 individual lumbar pedicle screws navigation modules. All of anchor pointes and directions of 228 lumbar pedicle screws screws are consistent with virtual nailing scheme. The position of pedicle screws are pretty good, none of lumber pedicle screws throughout pedicle cortex. Most anchor points of lumber pedicle screws are in the central part of the herringbone crest. The position of lumbar pedicle screws are accurate in the center of the lumber pedicles, the distances between the up, down, inside and outside wall are moderate.(2) The numerical value of design individualized lumbar pedicle screws navigation module is scope from7mm to 9 mm in diameter and scope from 25mm to 35mm in length. In these range, individualized lumbar pedicle screws navigation modules joint closely with the lumber herringbone crest. Individualized lumbar pedicle screws navigation modules fix firmly and easy to application. At the same time, we as much as possible to reduce removing soft tissues around herringbone crest, namely to reduce damage to the patients themselves. According to the actual needs of different patients, the diameter of the lumbar pedicle screws implanted are generally about 70% of the lumbar pedicle transverse diameter, the length of the lumbar pedicle screws are generally about 80% of the nail length.ConclusionBased on the digital design, the 3D printing individualized lumbar pedicle screws navigation module can effectively assist embed lumbar pedicle screws. This method is very easy to operate and has following characters such as simple procedure, short learning curve, high accuracy and low radiation exposure. In addition, this method needn’t enough surgical experience of performer and need lower technical requirements. Consequently, it is easy to popularize.Clinical application of lumbar pedicle screws accurate placement assisted by 3D printing navigation modulesObjectiveBased on digital design, the 3D printing individualized lumbar pedicle screws navigation modules are applied in the actual clinical patients with fracture of lumbar spine in order to the evaluation of the feasibility and accuracy of the lumbar pedicle screws implanted by individualized lumbar pedicle screws navigation modules in clinical, to realize individualized implant of lumbar pedicle screws in high accurately under the minimally invasive.MethodsWe collect 2 cases of adult patients’ CT data with lumbar vertebral compression fractures. Then, we import CT data to Mimics14.0 and 3D reconstructed patients’ virtual lumbar 3D models. Through digital design individualized lumbar pedicle screws navigation modules and using 3D printers to make lumbar pedicle screws navigation modules and lumbar entities. Preoperatively, we, firstly, use the individualized lumbar pedicle screws navigation modules on the 3D lumbar spine specimen to simulate implant lumbar pedicle screws. After that, we take individualized lumbar pedicle screws navigation modules into the operating room after disinfection. Intraoperative, we apply individualized lumbar pedicle screws navigation modules to embed lumbar pedicle screws. Finally, through the postoperative X-ray and CT examination, we evaluate the effect of implantation of lumber pedicle screws.ResultsThrough digital design and 3D printing, we create 12 individual lumbar pedicle screws navigation modules in total and apply navigation modules to embed 12 lumbar pedicle screws. All of 12 lumbar pedicle screws are located within the lumber pedicles and the location of the screws in the lumbar pedicle are pretty good, none of lumber pedicles screws wear out lumbar pedicle cortex and no complications. Pedicle screws implantation accuracy is high. All of lumber pedicle screws anchor points and directions are highly consistent with the preoperative simulation scheme.ConclusionBased on the digital design and 3D printing, individualized lumbar pedicle screw navigation modules can help implant lumbar pedicle screws in a high level of accuracy, which is characterized by simple operation, easy to learn and can realize individualized lumbar pedicle screws accurate implant under minimally invasive.3D printing individualized lumbar pedicle screws navigation modules is easy to promote to the basic-level hospitals, which will help young doctors who are lack of operation experience and technology to complete pedicle screws implantation surgery.