357 Image-Guided Farlateral Lumbar Foraminotomy and Microdiscectomy: Operative Technique and Outcomes

INTRODUCTION: Three dimensional image-guidance is frequently used to improve the safety of complex spine surgeries. Its adoption remains mostly limited as and aid with instrumentation placement. METHODS: We performed a retrospective chart review of image-guided farlateral foraminotomies and microdiscectomies performed by a single surgeon from January 2018 to July 2021. Demographics, operative times and outcomes were collected. The stealth reference arc is fixated on the patient's skin using the Ioband. The O-arm is used to perform an intraoperative CT-scan automatically registered to the image-guided system. The location of the paraspinal incision is ascertained using the image-guided dilator to allow adequate trajectory to the neural foramen that minimizes the amount of facet joint that needs to be removed. The foraminotomy and/or discectomy is accomplished using microsurgical technique. Image guidance can be used to help guide the foraminotomy. RESULTS: 20 patients were included in our study; 14 (70%) underwent image-guided farlateral microdiscectomy and 6 (30%) foraminotomy. The most common microdiscectomy level was L5-S1 (50%). Mean age was 66 ± 10.2 (SD) years; 16(80%) were male; BMI 27.5 ± 3 kg/m 2 ;. Total procedure time was 117.4 ± 24.6 minutes; OR time 172.5 ± 22.5 minutes; EBL 21.5 ± 16.6 ml. Average length of stay 0.85 ± 0.6 days, with 5 (25%) discharge on the same day; all patients were discharged home. We did not observe intraoperative complications; all patients reported significant improvement of their presenting symptoms. Mean follow-up was 19.4 ± 28.7 months. CONCLUSIONS: FDA-approved use of spinal image-guidance requires a reference arc to be attached to the bony spine. Our technique of attaching the reference arc to the skin is an off-label use, we do not recommend it for instrumentation placement as there is mild navigation inaccuracy (2-3 mm). This technique allows for general accuracy to ascertain the location of the incision and trajectory and can help guide the foraminotomy.