Pathological Patterns and Technical Considerations in Transforaminal Endoscopic Lumbar Foraminotomy for Fusion-Segment Radicular Pain.

PURPOSE: This study aimed to describe the predominant pathological patterns observed intraoperatively, the endoscopic decompression techniques used, and the clinical outcomes of transforaminal endoscopic lumbar foraminotomy (TELF) for fusion-segment radicular pain. PATIENTS AND METHODS: This retrospective descriptive case series included 14 consecutive patients who underwent TELF for unilateral radicular pain caused by foraminal pathology within a previously fused lumbar segment. The compressive pathology was assessed preoperatively using magnetic resonance imaging and computed tomography scan. Then, it was confirmed or further characterized intraoperatively via direct endoscopic visualization. Clinical outcomes were evaluated using the visual analog scale (VAS), Oswestry Disability Index (ODI), and modified MacNab criteria during a 12-month follow-up period. RESULTS: The pathological findings were categorized as perineural adhesion (n = 8, 57.1%), screw-related impingement (n = 4, 28.6%), and foraminal disc herniation (n = 2, 14.3%). The mean VAS score for leg pain decreased from 8.29 ± 0.61 preoperatively to 1.86 ± 1.23 at 12 months postoperatively (p < 0.001). The mean ODI decreased from 71.83% ± 4.79% to 16.89% ± 11.08% (p < 0.001). According to the modified MacNab criteria, 85.7% of the patients achieved excellent or good outcomes. Two patients developed transient postoperative dysesthesia, and one case of incidental dural tear was successfully managed endoscopically. None of the patients required revision fusion or repeat decompression during the 12-month follow-up. CONCLUSION: TELF may offer a minimally invasive treatment option for fusion-segment radicular pain while preserving the existing fusion construct. Identifying the predominant compressive pathology may facilitate pathology-oriented endoscopic decompression in appropriately selected patients.