1. 2020;23;E629-E636Endoscopic Surgical Resection of the Retropulsed S1 Vertebral Endplate in L5-S1 Spondylolisthesis: Case Series
   Retrospective Chart Review
   Ziya L. Gokaslan, MD, Albert E Telfeian, MD, PhD, Jared Fridley, MD, Adetokunbo Oyelese, MD, PhD, and Sohail Syed, MD.

BACKGROUND: A severe grade I and grade II spondylolisthesis at L5-S1 creates an anatomic distortion that can compress the traversing S1 nerve with a retropulsed S1 vertebral body endplate and (sometimes) herniated disc.

OBJECTIVES: To evaluate the feasibility for awake, endoscopic treatment of symptomatic radiculopathy secondary to the deformity that results from the retropulsed superior endplate of S1 in grade I/II L5-S1 spondylolisthesis in patients with and without previous fusion surgery.

STUDY DESIGN: Retrospective chart review.

SETTING: This study took place in a single-center, academic hospital.

METHODS: In 325 patients over 4 years there were 19 patients (8 with previous L5-S1 fusions and 11 without) treated with transforaminal endoscopic spine surgery for decompression of the neural foramen at L5-S1 in the setting of spondylolisthesis (at least 5 mm) and a retropulsed superior vertebral endplate of S1.

RESULTS: The average preoperative Visual Analog Scale (VAS) back and leg scores were 6.1 and 6.7, and the average preoperative Oswestry Disability Index (ODI) score was 50.4. The average 1-year VAS back and leg scores were 2.2 and 2.2, and the average 1-year postoperative ODI score was 20.5. There was no statistically significant difference between the fusion and nonfusion groups. Patients treated were patients who presented with an S1 or L5 and S1 radiculopathy as their primary complaint and a L5-S1 spondylolisthesis of 5 mm or greater. Patients treated had no instability on flexion-extension x-rays. Eleven patients had not had fusions at L5-S1, and 8 patients had previous fusions at L5-S1 but still had a spondylolisthesis of at least 5 mm. The average slip for nonfusion patients was 8.4 mm, and the average slip for fusion patients was 8.8 mm. At 1-year follow-up the improvement in VAS back scores was 44% in the nonfusion group and 49% in the fusion group, and the improvement in VAS leg scores was 84% in the nonfusion group and 58% in the fusion group. At 1-year follow-up the improvement in ODI scores was 63% in the nonfusion group and 54% in the fusion group.

LIMITATIONS: Retrospective case series.

CONCLUSIONS: Awake, endoscopic surgery for the treatment of radiculopathy in the setting of a grade I/II L5-S1 spondylolisthesis is a viable minimally invasive treatment option for patients with radiculopathy in the setting of a stable L5-S1 spondylolisthesis with foraminal narrowing caused by a retropulsed superior endplate of the S1 vertebral body.

KEY WORDS: Endoscopic spine surgery, minimally invasive spine, transforaminal, spondylolisthesis