Clinical and Radiologic Outcomes of Single-level Decompression by Unilateral Endoscopic Biportal Technique in Degenerative Spinal Stenosis: Over 5-year Follow-up

Study Design: Retrospective. Objective: To report radiologic and clinical outcomes of single-level unilateral biportal endoscopic (UBE) decompression over 5 years for degenerative lumbar spinal stenosis (LSS) without instability. Summary of Background Data: UBE decompression has recently been introduced as a surgical treatment for LSS without instability. UBE has been shown in studies to have advantages in the prevention of infection and early rehabilitation. However, there is no long-term follow-up study. Methods: One hundred twenty-seven patients who underwent UBE decompression for single-level LSS with at least 5 years of follow-up were analyzed. Clinical outcomes including Oswestry Disability Index (ODI), Visual analog system (VAS), modified MacNab criteria, time to ambulation, operative time, and length of hospital stay were investigated. The radiologic outcome was assessed by dynamic plain radiographs. Results: ODI improved from 63.2±10.7 before surgery to 18.8±9.2 after 5 years of follow-up (P<0.001). Leg VAS decreased from 7.3±0.7 before surgery to 1.75±0.5 at the last follow-up (P<0.001). Per modified Macnab criteria, only 9.4% (12/127) showed poor clinical results. There were no infections, but there were 4 cases (3%) of dura tear and 1 case (0.07%) of transient palsy. Intervertebral angle showed significant change from preoperative to final follow-up, 6.3 ±3.2-5.2 ±3.5 degrees. (P=0.012). The intervertebral distance also showed a significant difference from 10.5±2.3 mm before surgery to 9.1±2.2 mm after surgery. (P=0.005). No significant changes in dynamic stability occurred. Among 127 patients, revision surgery was performed in 9 cases (7%). Conclusions: UBE decompression of LSS without instability demonstrated good clinical outcomes over 5 years and did not show significant segmental instability after surgery. Although revision surgery was performed after UBE decompression, there were no severe complications, and revision rates were similar to other techniques. UBE is considered to be an alternative technique to microscopic and traditional decompression in LSS.