Abstract: Objective To evaluate the clinical application value of unilateral biportal endoscopy (UBE) in the management of adjacent segment disease (ASD) following posterior lumbar fusion.Methods Between January 2022 and April 2024,a total of 28 patients with symptomatic adjacent segment lesions after prior posterior lumbar fusion underwent UBE surgery for either endoscopic discectomy or unilateral laminotomy for bilateral decompression (ULBD) via the contralateral approach.Intraoperative and postoperative outcomes,including operative duration,length of hospital stay,drainage volume,and complications,were recorded.The visual analogue scale (VAS) scores for back and leg pain,as well as the Oswestry Disability Index (ODI),were assessed preoperatively and at 1,6,and 12 months postoperatively,with additional evaluation at the final follow-up.Results All procedures were successfully completed in the 28 patients.The mean follow-up period was (19.3±3.5)months (range:16-24 months).The mean operative time was (68±30)minutes (range:54-98 minutes).Postoperative computed tomography confirmed adequate neural decompression,with preservation of more than 50% of the facet joint on the operated side.VAS scores for low back pain,leg pain,and ODI values at 1,6,and 12 months postoperatively,as well as at final follow-up,showed significant improvement compared to preoperative levels (P<0.05).At the final followup,functional outcomes based on the modified MacNab criteria revealed 21 excellent,4 good,3 fair,and 0 poor results,yielding an excellent and good rate of 89.3%.One patient experienced a dural tear,which was managed endoscopically with suture repair and external compression;the drainage tube was removed after 7 days.Another patient developed a postoperative hematoma with transient radiculopathy,which resolved following conservative treatment with corticosteroids and mannitol.Follow-up MRI one week later confirmed hematoma absorption without evidence of spinal instability.Conclusion Unilateral biportal endoscopy demonstrates favorable outcomes in the treatment of adjacent segment disease following posterior lumbar fusion,offering minimal invasiveness,and promising early clinical efficacy.It represents a viable minimally invasive option for revision surgery in this patient population.

Key words: unilateral biportal endoscopy, posterior lumbar fusion surgery, adjacent segment disease