121. Machine-vision image guided surgery (MvIGS): an intraoperative and radiation-free spine navigation system workflow analysis

BACKGROUND CONTEXT A worldwide survey conducted in 2013 reported that 78% of surgeons utilize 2D fluoroscopy during spine surgery. By comparison, and despite improved accuracy, computer-assisted spine navigation systems have lagged behind, largely due to increased costs, prolonged operative times and cumbersome surgical equipment. However, in recent years, computer-assisted spine navigation systems have grown in popularity as a result of decreasing costs and advancements in their user friendliness, thus improving integration into the surgical workflow. In an effort to address the growing concerns of current computer-assisted spine navigation systems, an emergent technology has been developed that does not require intraoperative ionizing radiation exposure. In addition to sparing the patient and surgeon to radiation exposure, this new spine navigation system, named the Machine-vision Image Guided Surgery (MvIGS) (7D Surgical, Toronto, Canada) system, is also projected to seamlessly integrate and therefore not contribute to prolonged operative times. By use of proprietary technology, localizing reference images are generated in a matter of seconds, as opposed to minutes, thus mitigating the disturbance to normal surgeon-defined workflow while maintaining accuracy. PURPOSE The purpose of this study is to prospectively compare clinical outcomes between the MvIGS spine navigation system to conventional 2D fluoroscopy in patients requiring posterior instrumentation in spine surgery. STUDY DESIGN/SETTING Prospective, single-center consecutive series. PATIENT SAMPLE Patients undergoing single- and multilevel posterior spine fusion surgery with pedicle screw instrumentation. OUTCOME MEASURES Our primary outcome measure is operative time. Secondary outcomes include demographic characteristics, intraoperative parameters and radiographic measurements including total exposure time (TET) and cumulative radiation dose (mGy). METHODS Radiographic and intraoperative data were collected from the first 26 patients enrolled in a large single-center, randomized prospective study comparatively evaluating 2D fluoroscopy to 3D MvIGS spine navigation in single and multilevel posterior spine fusion surgery. Intraoperative parameters assessed include mean operative time, estimated blood loss (EBL), total exposure time (TET) as measured in time (secs), and cumulative radiation dose (mGy) emitted by 2D fluoroscopy. Incidence of intraoperative complications, including dural tears or perioperative new/worsening neurological deficits, as well as mean length of hospital stay (LOS), were also collected. In patients undergoing circumferential spine surgery, only data pertaining to posterior instrumentation were collected. RESULTS Over 100 screws were implanted into 26 patients, 12 male and 14 female, with a mean age and BMI of 60.4 years and 29.8, respectively. Mean operative time between 3D and 2D imaging was 236 and 251 minutes, respectively. No significant difference in total exposure time (seconds) and cumulative radiation dose (mGy) were recorded with 3D navigation exhibiting an average of 27.4 and 14.3 respectively, compared to 2D's 28.8 and 16.1, respectively (p=1.0). Fifty-six percent (56%) of cases were multilevel fusion procedures, with nearly 90% involving the L4-5 vertebral segment. Mean intraoperative EBL and length of hospital stay were 390 mL and 3.5 days, respectively, with no significant difference between treatment groups. No new neurological deficits or complications were recorded. CONCLUSIONS Use of navigation systems in spine surgery is often cumbersome and time consuming, frequently disrupting surgeon workflow and prolonging operative times. Results from our cohort analysis demonstrate no significant difference in operative times between groups, indicating minimal workflow disruption. We believe two predominant theories as to why the MvIGS spine navigation system has resulted in minimal workflow disturbance. The integration of the navigation camera into the surgical light eliminates the need to stop surgery, drape and position supplemental surgical equipment, thereby allowing for continuous access to the surgical field. Secondly, and unique to the MvIGS system, the reference clamp can be repositioned and re-registration images completed within 20 seconds. This combination allows for seamless clinical applicability and reverses many of the well-documented drawbacks of preceding navigation systems. We believe we are the first to report on the clinical application of this radiation-free MvIGS technology in spine surgery. FDA DEVICE/DRUG STATUS Machine-Vision Image Guided Surgery (MvIGS) (Approved for this indication).