Early clinical experiences with spine electromagnetic navigation Early clinical experiences with spine electromagnetic navigation. Pitfalls and benefits. Prof. Dr.med. A. Alfieri Lugano, 24.5.2018 NEUROCHIRURGIE

Disclosure Fiagon (complimentary use of the system)

Is the navigation necessary? Is the EM-navigation reliable? EM-navigation as alternative to optical navigation and/or intraoperative CT? i wanna to discuss 3 points.

Is the navigation in spine surgery necessary? In 21% of the specimens pedicle screws violated the cortex, when inserted using anatomical landmarks. Weinstein Jnet al: Spinal pedicle fixation: reliability and validity of roentgenogram based assessment and surgical factors on successful screw placement. Spine (13:1012–1018, 1988 The issue is well discussed in neurosurgical and orthopedic community In a cadaveric study by Weinstein et al.,pedicle screws violated the cortex in 21% of the specimens when inserted using anatomical landmarks. Puvanesarajah et al. World J Orthop. Apr 18, 2014;

Is the navigation in spine surgery necessary? Allowing a 3D-image Reducing complications Reducing reoperation due to malposition Small pedicles Altered anatomy and defomity Waschke et al. CT-navigation versus fluoroscopy-guided placement of pedicle screws at the thoracolumbar spine: single center experience of 4,500 screws, Eur. Spine. J. 22 (2013) (3):654-60. The use of navigated surgery in pedicle screw placement allows a three-dimensional image of the vertebra to be obtained in real time, improving the accuracy of screw placement and decreasing the malposition rate up to 3.6% (range 0-11%), thus reducing the complications derived from screw malpositioning. Additionally, a decrease has been observed in the reoperation rate due to screw malposition from 8.8% in conventional surgery to 2.9% in navigated surgery. The comparative studies in the literature regarding navigation versus fluoroscopy are favorable to navigation with a difference in errors that was statistically significant in all of the studies, a difference that increases with small pedicles and altered anatomies, as in the case of deformities J. Tang, et al. , Position and complications of pedicle screw insertion with or without image-navigation techniques in the thoracolumbar spine: a meta-analysis of comparative studies, J. Biomed. Res. 28 (2014) (3):228-39.

Is the navigation in spine surgery necessary? Reducing radiations E.M. Nelson, S.M. Monazzam, K.D. Kim, .A. Seibert, E.O. Klineberg, Intraoperative fluoroscopy, portable X-ray, and CT: patient and operating room personnel radiation exposure in spinal surgery, Spine J. 14 (2014) 12):2985-91. Regarding the radiation received in navigated surgery , radiation rates received by both the surgical team and the patient lower than with conventional surgery has been observed

Only 11% of surgeons in North America and Europe used navigation in spite of its widespread availability. Härtl R, et al: Worldwide survey on the use of navigation in spine surgery. World Neurosurg 79:162–172, 2013 In a global survey by Härtl et al. regarding the use of navigation, only 11% of surgeons in North America and Europe used navigation in spite of its widespread avail- ability.

No, It Isn’t But I (and my patients) want it Is the navigation in spine surgery necessary? today No, It Isn’t But I (and my patients) want it Spinal navigation should be thought of as an adjunct to thorough knowledge of spinal anatomy and not be used as a substitute for it. The question is not “if” we will use navigation, but “when” and “which one” my personal philosophy regarding navigation Anatomy, anatomy, anatomy…….

Our technical facilities Carbon OP-table (Maquet) 3D-fluoroscopy (Orbic Siemens) Intraoperative Monitoring (IOM) Optical navigation system (Stryker) EM navigation system (Fiagon) core nova (Wolf) spinal navigation and intraioperative neuromonitoring play a central role in our clinic

Navigation Systems since 2007 since July 2016 the size is reduced, the em navigation is made through a small box. you know how busy are OR today

Assessment Feasibility clinical study EM Alternate use of an optical navigation system (Stryker) 9 cases (opt) vs 10 cases (EM) both cohorts comprises simple, medium and complex procedures with simple lumbar one-level spondylodesis, more complex thoracic spondylodesis and challenging cervicotoracic cases.

one-level spondylodesis

multilevel dorso-lumbal spondylodesis at thoracolumbal junction

Preoperative Considerations CT scan (1-mm-thick) Surgical Learning Curves Surgical table selection (nonmetallic carbon operating table to prevent interference from metallic objects) Prior to starting a spinal fusion procedure, various operative considerations such as positioning, neuromonitoring, and equipment require appropriate selection. A CT scan with a 1 mm slice thickness was made and then the data set was imported to the navigation system in DICOM format. From this data set, a high-resolution three-dimensional VRT (volume-rendered tomography) model was calculated by the navigation system that was used for navigation. The system simultaneously calculated another 3D data set for navigation in all plane Surgeon learning curve was very steep, the system was intuitive to use A nonmetallic carbon operating table to prevent interference from metallic objects will be selected s.

Electromagnetic field, Tracking System and Instruments special field generator placed below the patient (non-sterile area) covers the entire surgical field the instruments with signal coils ican be detected. Tracking System and Instruments A special field generator was used to generate the electromagnetic field (EMF). The field generator was placed below the patient (non-sterile area) so that the frame encompassed the entire surgical field. The EM Field This field generator forms an electromagnetic field in which the instruments in the field fitted with signal coils can be detected.

Electromagnetic field, Tracking System and Instruments A reference coil (patient tracker)was attached to the spinous process All instruments can be provided with refereeing system, so that the surgeon will not change his surgical technique Tracking System and Instruments A special field generator was used to generate the electromagnetic field (EMF). The field generator was placed below the patient (non-sterile area) so that the frame encompassed the entire surgical field. The EM Field This field generator forms an electromagnetic field in which the instruments in the field fitted with signal coils can be detected.

Step Key Points Optical Navigation Step Key Points EM Navigation setup position camera to maximize line of sight monitor so easily visualized by surgeon patient positioning insert instrumentation immediately after registration briefly check navigation accuracy on patient anatomy prior to placement of each screw avoid excessive banging on instruments & movement of spine be aware of flexible spines (adolescent scoliosis patients & trauma patients) do not bend image-guided instruments always remember that the images on the screen are not in real time maintaining line of site place reference arc between the camera & the working space for image-guided instruments avoid placing objects (suction, clamps) in front of reference arc avoid shining light (headlight, overhead lights) directly on reference arc computer-surgeon interface surgeon or qualified OR staff interfaces & drives computer consider intraoperative planning function of image-guided system during screw placement wireless Placing of the EM -field generator continuous tracking of the instruments and the patient’s anatomical structures during the entire surgical procedure be aware of flexible spines (adolescent scoliosis patients & trauma patients) always remember that the images on the screen are not in real time bend the image-guided instruments will not affecting the procedure surgeon can perform normal standard procedure consider intraoperative planning function of image-guided system during screw placement fluoroscopy should be placed carefully, interference! wired I summarize briefly the key points of both techniques

Optical Navigation EM Navigation Patients: 9 Cervical screws: 10 Thoracic screws: 18 Lumbal screws: 38 Misplaced 1/66(lateral) Navigation Working for 62/66 Patients: 10 Cervical screws: 12 Thoracic screws: 18 Lumbal screws: 38 Misplaced 2/68 (lateral) Navigation Working in 58/68 (kyphosis, obese)

Pitfalls Benefits continuous tracking of the instruments Obese patients Kyphosis Fluoroscopy Special wired instruments continuous tracking of the instruments system can correct static errors using special calibration and correction methods no permanent optical connection (line of sight) of the components is required the operator’s workflow is not impaired navigation can take place without intraoperative X-ray guidance, potential for outpatient procedures or obese patients the deliver of poorer quality images that can make the registration pro-cess inaccurate, as well making the images difficult to use during surgery. ADDICTIONALLY; THE em- FIELD SHOULD BE VERY ENLARGED AND NOT ALWAYS POSSIBLE: Prior to starting a spinal fusion procedure, various operative considerations such as positioning, neuromonitoring, and equipment require appropriate selection. The surgical team is responsible for dissemination of information to OR personnel, who will in turn organize the OR For obese patients the deliver of poorer quality images that can make the registration pro- cess inaccurate, as well making the images difficult to use during surgery. ADDICTIONALLY; THE em- FIELD SHOULD BE VERY ENLARGED AND NOT ALWAYS POSSIBLE: Surgeon learning curves when new technology emerges have been reported in robotic and laparoscopic surgery. The components of the learning curve include the ability to direct instruments based on imaging visualized on a screen, the ability to replicate in-line maneuvers while placing instrumentation, as well as adopting and developing proper technique while using image-guided technology. A CT scan with a 1 mm slice thickness was made of all specimens required and a 3D reconstruction was generated (Institute for Diagnostic and Interventional Radiology, Düsseldorf University Hospital, Germany). The data set was used to plan the navigation; for this the diameter of the respective pedicle was calculated and trajectory was determined. For further intraoperative processing and navigation, the data set was imported to the navigation system in DICOM format. From this data set, a high-resolution three-dimensional VRT (volume-rendered tomography) model was calculated by the navigation system that was used for navigation. The system simultaneously calculated another 3D data set for navigation in all planes.

Challenges enlarge/optimize the EM field provide a reference system for percutaneous and endoscopic procedures EM Spinal Navigation is an exciting technology which is continuously adding to the ability, efficiency and accuracy in treating a variety of complex spine problems.

Is the navigation necessary? Is the EM-navigation reliable? EM-navigation as alternative to optical navigation and/or intraoperative CT? i wanna to discuss 3 points.

Join us ! Further steps Multicentric randomized controlled study Start April 2019 Join us ! alex.alfieri@ksw.ch