204. A review of time-demand, radiation exposure and outcomes of skin-anchored intraoperative 3D navigation in minimally invasive lumbar spinal surgery

Abstract

BACKGROUND CONTEXT Real time image-guidance and intraoperative 3-dimensional navigation (ION), which utilize either a bone- or skin-anchored tracker, are increasingly being utilized in spine surgery to provide better visualization of abnormal anatomy, improve accuracy and enable less invasive procedures. However, ION is associated with considerable upfront costs, intraoperative time-demand and potentially greater radiation exposure. PURPOSE To describe the time demand, radiation exposure and outcomes of ION using a skin-anchored tracker in minimally invasive lumbar surgery. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE All patients who underwent 1-level MIS microdiscectomy, laminectomy or TLIF by a single surgeon from April 2017 to January 2018. OUTCOME MEASURES Operative time, fluoroscopy time and radiation dose. METHODS Operative variables, radiation exposure and short-term outcomes of all three surgical procedures were summarized using descriptive statistics. RESULTS Of the 232 patients in this study, 92 underwent a microdiscectomy, 65 a laminectomy and 75 an MI-TLIF. All procedures were performed using a tubular retractor system, operating microscope and skin-anchored ION. Time required for ION set-up, measured as the time taken from completion of anesthesia induction to the start of the surgical procedure was a median of 22 minutes (IQR 19–25) for microdiscectomy, 23 (IQR 21–26) for laminectomy and 24 (IQR 21–28) for MI-TLIF. 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 seconds (IQR 9–10) for microdiscectomy, 9 (IQR 9–10) for laminectomy and 26 (IQR 20–34) for MI-TLIF. Of this, an average of 9 seconds was required for image-acquisition for ION, while the remaining fluoroscopy time was for the surgical procedure (median 0, 0 and 17 seconds for microdiscectomy, laminectomy and MI-TLIF respectively). The total radiation dose was a median of 15.2mGy (IQR 8.6–23.9) for microdiscectomy, 16.6 (IQR 10.85–27.2) for laminectomy and 44.6 (IQR 35.6–64) for MI-TLIF. Of this, the median radiation dose required for image acquisition for ION was 93%, 95% and 37% of the total dose for microdiscectomy, laminectomy and MI-TLIF respectively, with the rest attributable to the surgical procedure. The operative time was a median of 42 minutes (IQR 35–54) for microdiscectomy, 50 (IQR 39–58) for laminectomy and 92 (IQR 77–101) for MI-TLIF. For all three procedures, median blood loss was 25 ml, the only reported intraoperative complication was durotomy, occurring in 1 patient undergoing laminectomy, and the most common in-hospital complication was urinary retention requiring catheterization, seen 0%, 3.1% and 6.7% of microdiscectomies, laminectomies and MI-TLIFs respectively. There were no wrong-level surgeries in any patients. CONCLUSIONS The use of intraoperative navigation using a skin-anchored navigation tracker is a feasible, safe and accurate approach. For decompression surgeries, a majority of the radiation dose and fluoroscopy time is attributable to image-acquisition for ION. In contrast, image-acquisition accounts for FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.