P104. A review of time demand, radiation exposure and outcomes of skin-anchored intraoperative 3D navigation in minimally invasive posterior cervical laminoforaminotomy

Abstract

BACKGROUND CONTEXT Real time image-guidance and intra-operative 3-dimensional navigation (ION) are increasingly being utilized in spine surgery to provide better visualization, improve accuracy and enable less invasive procedures. Studies have shown effective early adaption and radiation reduction with this technology in minimally invasive lumbar spine surgery. However, the novel use of a noninvasive skin-anchored tracker has not yet been described for cervical spine surgery. PURPOSE To describe the time demand, radiation exposure and outcomes of ION using a skin-anchored tracker in minimally invasive posterior cervical laminoforaminotomy (MI-PCLF). STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE All patients who underwent MI-PCLF by a single surgeon from April17-November 19. OUTCOME MEASURES Time for navigation set-up, operative time, estimated blood loss (EBL), radiation exposure to operating room (OR) personnel and the patient, complications and length of stay. METHODS Operative variables, radiation exposure and perioperative outcomes were summarized using descriptive statistics. RESULTS Twenty-one patients (36Levels) with a mean age of 55+11.79yrs, BMI of 27.36+2.95kg/m2, and comprising 17(81%) males were included. A majority of cases were 1-level (9; 42.9%) or 2-level (10; 47.6%), with only one 3-level and one 4-level surgery. The operative levels were: C3C4 (11.1%), C4C5 (19.4%), C5C6 (22.2%), C6C7 (25%), C7T1 (22.2%). Time required for ION set-up, measured as the time from end of anesthesia induction to the start of the surgical procedure was a median of 34 mins [IQR 30-37]. This accounts for the time required for patient positioning, preparing and draping the incision site, placing the skin-anchored navigation tracker and acquiring a 3D image for real-time navigation. The total fluoroscopy time was a median of 10 sec [IQR 9-11], almost entirely attributable to ION image-acquisition; and radiation dose was a median of 2.5mGy [IQR 1.8-4.9]. Thus, radiation exposure to the patient was minimal. Since all OR personnel are behind a protective lead shield during ION image-acquisition, radiation exposure to the surgeon and OR team was negligible. One patient required a repeat ION spin, resulting in the fluoroscopy time for ION image-capture being 20sec. In two patients, ION was abandoned and the procedure was completed using fluoroscopy resulting in the total fluoroscopy time being 17&27sec (9sec for ION spin; rest for fluoroscopic guidance). Additionally, one patient had a radiation dose of 13.9mGy, which is almost three times the 75th percentile dose. Although the exact reason could not be determined, this may be attributable to a number of factors including deliberate or inadvertent higher dose settings, difference in C-arm position, calibration error, etc. Operative time was 62 mins [IQR 53-74] and EBL was low (25ml [IQR 25-25]. There were no wrong level surgeries, or any intra or post-operative complications. Median post-operative length of stay was 6hrs [IQR 4.4-20.9], with a majority (66.7%) of patients being discharged on the day of surgery. CONCLUSIONS The results of our study suggest that the use of intraoperative navigation using a skin-anchored tracker for posterior cervical laminoforaminotomy is a feasible, safe and accurate technique, resulting in short operative times and minimal complications. Further, it results in negligible radiation exposure to the OR team and low radiation exposure to the patient. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.