Posterior inclinatory approach for degenerative foraminal stenosis with the biportal endoscopic technique: clinical and radiological outcomes

Background Although there are several surgical applications to treat foraminal stenosis, difficulties in some cases need novel access to decompression and preserve normal structure simultaneously. Biportal endoscopic spine surgery (BESS) presents a multitude of advantages, including enhanced flexibility, improved magnification, and an expanded field of view. We introduce a novel posterior inclinatory access in BESS (PIA-BESS) that is specifically designed to treat some specific degenerative foraminal stenosis and evaluate its clinical and radiological outcomes. Methods Between March 2021 and July 2023, 19 patients presenting with symptomatic nerve root involvement due to foraminal stenosis underwent the PIA-BESS surgical procedure. Preoperative and postoperative assessments involved magnetic resonance imaging (MRI) and computed tomography (CT) scans to measure changes in the cross-sectional area of the spinal canal and intervertebral foramen. Clinical outcomes were evaluated using the Oswestry Disability Index (ODI) scores and the visual analog scale (VAS) scores for buttock and radicular pain. The dynamic intervertebral angle (IVA) and vertebral slip rate, as determined from preoperative and postoperative X-rays, were employed to evaluate post-surgical vertebral stability. Results The intervertebral foraminal area increased significantly from the initial measurement of 32.26 ± 13.49 mm2 to 79.95 ± 19.78 mm2 (P<0.05). Similarly, the spinal canal area also showed a significant increase, from 105.37 ± 21.66 mm2 to 145.63 ± 17.86 mm2 (P<0.05). ODI scores reduced significantly from 73.27 ± 13.21 to 9.26 ± 7.65 (P<0.05), and VAS scores reduced significantly from 5.79 ± 1.08 to 0.84 ± 0.90 (P<0.05). Notably, there were significant differences between the pre-operation and post-operation measurements. However, no significant changes were observed in the dynamic IVA and vertebral slip rate. Conclusions The PIA-BESS approach is an effective and low-complication method for addressing stenosis in the lumbar foraminal region. It provides effective decompression for bony stenosis or extruded and sequestered discs in the foraminal region, while preserving the normal structure to maintain the spine stability.