Clinical outcomes of uni-portal non-coaxial spinal endoscopic surgery for severe caudally migrated lumbar disc herniation with free fragments

Abstract

To evaluate the clinical efficacy and perioperative safety of uni-portal non-coaxial spinal endoscopic surgery (UNSES) for the treatment of severe caudally migrated lumbar disc herniation with free fragments. A retrospective study was conducted on 75 consecutive patients with single-level severe caudally migrated lumbar disc herniation who underwent UNSES at a single center between July 2024 and February 2025. Perioperative data and postoperative complications were retrospectively collected. Clinical outcomes were assessed using the visual analogue scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and the Japanese Orthopaedic Association (JOA) score before surgery and at 3 days, 3 months, 6 months, and 12 months after surgery. Overall clinical outcomes at the final follow-up were evaluated according to the modified Macnab criteria. Outcome measures at each follow-up time point were compared with baseline values. All patients successfully underwent UNSES without requiring conversion to open surgery. The mean operative time was 83.81 ± 10.95 min. All incisions healed by primary intention, and no symptomatic epidural hematomas were observed. Perioperative complications included two dural tears and six cases of transient neurological deficits. All patients recovered gradually following conservative management during follow-up. Recurrence occurred in one patient. All patients completed the 12-month follow-up. At the final follow-up, the mean leg pain VAS score decreased from 7.35 ± 0.73 to 1.44 ± 0.55, while the mean back pain VAS score decreased from 6.73 ± 0.83 to 1.37 ± 0.49. The mean ODI decreased from 65.20 ± 6.04 to 14.76 ± 1.78, whereas the mean JOA score increased from 11.96 ± 1.60 to 24.31 ± 1.92. Significant improvements in VAS, ODI, and JOA scores were observed at all postoperative follow-up time points compared with baseline. At the final follow-up, the excellent and good rate according to the modified Macnab criteria was 91%. UNSES effectively relieves pain and improves lumbar function in patients with severe caudally migrated lumbar disc herniation with free fragments while maintaining an acceptable perioperative safety profile. Short- and mid-term follow-up results suggest that UNSES is a safe and feasible minimally invasive treatment for this challenging type of lumbar disc herniation. However, high-quality prospective studies with longer follow-up are required to further validate its long-term efficacy and potential advantages over other endoscopic techniques.