Awake MIS-TLIF under Spinal Anesthesia: Screw Placement Accuracy and 1-year follow-up

Introduction: We assessed the accuracy of pedicle screws placed during awake minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) under spinal anesthesia and analyzed outcomes at the one-year follow-up.

Methods: We included patients that underwent awake MIS-TLIF under spinal anesthesia at an academic center from February 2020 to February 2022. To evaluate the accuracy of pedicle screw placement, a neurosurgery resident (G.D.) and a spine-fellowship trained neurosurgeon (K.A.I.) reviewed the postoperative CT scans, and independently scored each pedicle screw for accuracy utilizing the Gertzbein-Robbins classification.

Results: A total of 100 pedicle screws were inserted in 24 patients, with the most common level being L4-5. Median age was 63.5±16.5 (IQR) years, 42% male, median BMI 28±6 kg/m², and median American Society of Anesthesiology class was 2±1. Two patients underwent a two-level fusion, and 22 patients underwent a one-level fusion. Median estimated blood loss was 35±25 ml, median length of stay was 01 days, with 54% of patients going home on the day of surgery, and the only intraoperative complication was one durotomy. Median procedure time was 112±23.5 minutes, and median operating room time (including the spinal block) was 159.5±32.7 minutes; 67% of the screws were placed with navigation, and 33% were robotic-assisted (Mazor X); 99% of the screws were Gertzbein Robins grade A, and 1% Grade E. At the one-year follow-up, the CT scans showed no evidence of pseudarthrosis, and all patients reported improvement of their presenting symptoms.

Conclusion : Our study shows a high accuracy (99%) of pedicle screw placement in awake minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) under spinal anesthesia, and significant improvement of their symptoms at the one-year follow-up.