Transforaminal Unilateral Biportal Endoscopic Spinal Surgery for Extraforaminal Lumbar Disc Herniation: A Retrospective Observational Study

Biportal endoscopic spinal surgery (BESS) is recommended as a safer and less destructive option for lumbar disc herniations. However, limited data exist on clinical outcomes for extraforaminal lumbar disc herniation (ELDH) surgery. This retrospective study presents our preliminary experience with transforaminal unilateral BESS for ELDH.Patients with lumbar radiculopathy refractory to conservative treatment, diagnosed with ELDH by magnetic resonance imaging, and treated with transforaminal unilateral BESS in 2021-2023 in 2 institutions in Taiwan were eligible for inclusion. Those with lumbar spondylolisthesis grade 2 or more with segmental instability, history of drug abuse or psychiatric diseases, or with a follow-up duration <1 year were excluded. Primary outcomes included visual analog scale for pain, assessed at 1 week, 1 month, 6 months, and 1 year using generalized estimating equations analysis; success and satisfaction of BESS graded by the Macnab criteria; and perioperative complications. Secondary outcomes were operative time and hospital length of stay.Seventeen patients were included in the analysis, with a mean age of 65.8 years; 11 (64.7%) were males and 15 (88.2%) had no prior lumbar spine surgery. mean operative time was 107.9 minutes, and length of stay was 3.5 days. Graded by Macnab criteria, 16 (94.1%) of patients had good to excellent outcomes. Only 1 patient experienced complications. No recurrence/reoperation was observed. Generalized estimating equations analysis showed that postoperative visual analog scale scores decreased significantly at 1 week (adjusted Beta [aBeta] = -5.47, standard error: 0.29, P < 0.001), 1 month (aBeta = -5.82), 6 months (aBeta = -5.88), and 1 year (aBeta = -6.29).Transforaminal unilateral BESS is an alternative and feasible method for treating ELDH, producing good surgical outcomes with few complications and sustaining pain improvement. Future studies with larger patient numbers and comparisons between BESS and other minimally invasive techniques for ELDH are warranted.