Unilateral biportal endoscopic decompression for stable adjacent segment disease after lumbar fusion: Clinical and radiological outcomes

Purpose Adjacent segment disease (ASD) is a recognized complication following lumbar fusion, characterized by new symptomatic and radiological degeneration at levels adjacent to the fused segment. While revision decompression with extended fusion has traditionally been performed, minimally invasive fusion-sparing strategies such as unilateral biportal endoscopic (UBE) decompression have gained attention. High-level evidence regarding their effectiveness in carefully selected stable ASD remains limited. Methods This retrospective cohort study included 17 consecutive patients with clinically and radiologically confirmed ASD treated with isolated UBE posterior decompression between 2022 and 2025. Patients with radiographic instability requiring fusion were excluded. Clinical outcomes included Visual Analog Scale (VAS) scores for back and leg pain, Oswestry Disability Index (ODI), and walking capacity assessed by the self-paced walking test (SPWT). Radiological evaluation included MRI-based canal measurements and standing lateral radiographs assessing segmental kyphosis and sagittal alignment. Pre–post comparisons were performed using paired statistical analyses. Results Median age was 66 years (IQR 64–70). Significant postoperative improvements were observed in SPWT distance and duration ( p < 0.001), VAS-back and VAS-leg scores ( p < 0.001), and ODI ( p < 0.001). MRI demonstrated significant enlargement of canal dimensions at the ASD level ( p < 0.001). Segmental kyphosis improved modestly without deterioration of global sagittal balance. Two perioperative complications (one dural tear, one epidural hematoma) were managed successfully without permanent neurological deficit. Conclusion In carefully selected patients with stable ASD, UBE posterior decompression provides meaningful pain relief, functional improvement, and effective neural decompression while preserving sagittal alignment. This tissue-sparing approach may be considered a treatment option in selected high-risk or elderly patients. Level of evidence IV.