Transforaminal Percutaneous Endoscopic Discectomy for L3/4 and L4/5 Foraminal and Extraforaminal Lumbar Disc Herniation: Clinical Outcomes and Technical Note

Abstract

Study design: Retrospective cohort study.

Background: Foraminal and extraforaminal disc herniations account for 7 to 12% of lumbar herniated discs. Various surgical methods, including midline approaches with facetectomy and paramedian techniques, involve significant bone removal, risking spinal instability. The percutaneous transforaminal approach for endoscopic access to lateral disc herniations presents several advantages over traditional techniques and may be more suitable for these cases.

Objectives: This article evaluates the clinical outcomes and potential complications associated with the treatment of foraminal and extraforaminal lumbar disc herniations at the L3/4 and L4/5 levels in patients who have undergone transforaminal percutaneous endoscopic lumbar discectomy.

Materials and methods: Between 2016 and 2020, a total of 32 patients diagnosed with single-level lumbar disc herniation at the L3/4 or L4/5 foraminal or extraforaminal levels, who had not responded to conservative management, underwent transforaminal endoscopic discectomy. Follow-up evaluations were performed on postoperative day 1 and at 2 weeks, 6 weeks, 3 months, and 12 months. Both pre- and postoperative assessments employed the visual analog scale (VAS) and the Oswestry Disability Index (ODI) to quantify pain levels and functional outcomes. Clinical outcomes were assessed according to the MacNab criteria to determine the efficacy of the surgical intervention.

Results: The average age of patients was 52.6 years, with L4/5 (81.3%) and L3/4 (18.7%) being the most affected levels. The median follow-up was 18.2 months (range, 1-44 months). There was a significant reduction in VAS and ODI scores at follow-ups compared to preoperative levels ( p < 0.01). All patients with preoperative neurological deficits improved, though six patients (18.7%) experienced transient dysesthesia that resolved in 6 weeks. Per the MacNab criteria, clinical efficacy was excellent in 56.3% of patients, good in 37.5%, and fair in 6.2%.

Conclusion: Transforaminal endoscopic lumbar discectomy is a safe and effective minimally invasive procedure for foraminal and extraforaminal lumbar disc herniations at the L3/4 and L4/5 levels. It preserves spinal stability, minimizes blood loss, reduces postoperative pain, and allows for quicker recovery, presenting a strong alternative for patients needing surgery for these conditions.

Keywords: far lateral lumbar disc herniation; foraminal lumbar disc herniation; transforaminal endoscopic discectomy.

Fig. 1

The skin entry point is determined by a line parallel to the intervertebral disc space in a true posteroanterior view and a line between the tip of the spinous process and the dorsal facet in a true lateral view ( A ). The true posteroanterior view of the L4/5 level should demonstrate the spinous processes centrally aligned between the pedicles and parallel vertebral endplates ( B ). In a true lateral view, the vertebral endplates should be parallel, and the pedicles should be superimposed ( C ).

Fig. 2

The working sleeve is inserted into the base of the superior articular process. This area is relatively safe from iatrogenic nerve root injury as it provides the widest space from the exiting nerve root ( A and B ).

Fig. 3

Case illustration: A 62-year-old female presented with intense radiating left leg pain after twisting her back while attempting to reach for an object. The straight leg raise test produced negative results, while the femoral stretch test yielded positive findings. Magnetic resonance imaging in both sagittal ( A ) and axial ( B ) views revealed an extraforaminal disc herniation at the left side of the L4/L5 level (arrow). In the course of the transforaminal percutaneous endoscopic discectomy procedure ( C ), verification through posteroanterior ( D ) and lateral ( E ) C-arm images confirmed the precise advancement of a 6.9-mm working cannula to the base of the superior articular process. Subsequently, the endoscopic view demonstrated the removal of disc fragments located beneath the L4 exiting nerve root, resulting in the visual liberation of the tensioned nerve root ( F – H ).