Background The transforaminal (TF) approach in full endoscopic spine surgery (FESS) is the least invasive spinal surgery, as it can be performed under local anesthesia with only an 8-mm skin incision. Transforaminal FESS-based foraminotomy was first performed in the early 2000s for the decompression of foraminal stenosis. The technique has improved year by year over the past 2 decades. In our hospital, full endoscopic lumbar foraminotomy (FELF) has been performed since 2015. Since our development of the FESS undercutting laminectomy procedures in 2019, the size of the decompressed area achieved by FELF has increased. Objective To estimate the technical alteration of FELF over time by comparing the pre- and postoperative osseous foraminal areas (FAs) between traditional and advanced FELF techniques. Methods Fifty-two cases were retrospectively reviewed. In the early phase of FELF before 2019, partial or total resection of the superior articular process (SAP) was performed. Twenty-six of the patients were treated using the traditional FELF procedure (SAP-ectomy group). The remaining 26 underwent advanced FELF procedures, including SAP-ectomy, undercutting laminectomy, and removal of the ligamentum flavum (advanced FELF group). Clinical outcomes were assessed using the modified MacNab score. Pre- and postoperative osseous FAs were measured on sagittal computed tomography, and data were compared between the SAP-ectomy and advanced FELF groups. Paired and unpaired t tests were used for statistical analysis. Results By the modified MacNab score, the excellent/good rate was 82.6% in the SAP-ectomy group and 95.5% in the advanced FELF group. The improvement was greater in advanced FELF but not significantly. FA prior to surgery was 87.5 ± 27.0 mm2 in the SAP-ectomy group and 95.7 ± 34.3 mm2 in the advanced FELF group, with postoperative increases to 151.4 ± 45.5 mm2 and 195.3 ± 39.1 mm2, respectively (P Conclusion Full endoscopic foraminotomy techniques have evolved over time. The recently developed advanced FELF technique appears to safely and effectively achieve better clinical outcomes by significantly enlarging FA. Clinical Relevance The advanced FELF technique contributes to improved decompression of the exiting nerve root. Level of Evidence 3.
Mio et al. (Mon,) studied this question.