Transforaminal Endoscopic Lumbar Foraminotomy for Radiculopathy at the Fused Segment After Lumbar Fusion: Clinical Outcomes and Surgical Considerations

Background: Radiculopathy originating from a previously fused lumbar segment is a clinically relevant but often underrecognized problem. Progressive foraminal stenosis may develop due to postoperative structural changes, leading to mechanical irritation of the exiting nerve root. Transforaminal endoscopic lumbar foraminotomy (TELF) is a minimally invasive option, but its role in this setting is not well defined. Methods: In this retrospective cohort study, we included 36 consecutive patients who underwent TELF for symptomatic foraminal stenosis at a previously fused segment between 2020 and 2023. Clinical outcomes were assessed using the visual analog scale (VAS) for leg pain, Oswestry Disability Index (ODI), and modified MacNab criteria, with follow-up of up to 2 years. Radiographic and intraoperative findings were reviewed to explore the underlying mechanisms. Results: The mean VAS score improved significantly from 8.36 preoperatively to 2.00 at 2 years, and the mean ODI decreased from 70.9% to 16.8%. According to the modified MacNab criteria, 86.1% of the patients achieved excellent or good outcomes. Intraoperative findings revealed fibrotic or hypertrophic foraminal stenosis in 86.1% patients (n = 31), whereas 13.9% of patients (n = 5) showed pedicle screw-related nerve root irritation. Five patients experienced transient postoperative dysesthesia, and no postoperative instability was observed. Conclusions: Radiculopathy at the fused segment is primarily caused by progressive mechanical foraminal compromise after fusion. TELF provides effective symptom relief through direct decompression and may serve as a less invasive alternative to revision fusion in selected patients.