O‐Arm Navigation Enhances Facet Preservation Without Compromising Clinical Outcomes in <scp>UBE</scp> Decompression for Radiographically Stable Adult Degenerative Scoliosis: A Single‐Center Comparative Study

OBJECTIVE: In radiographically stable adult degenerative scoliosis (ADS), unilateral biportal endoscopic (UBE) decompression alone is effective in alleviating symptoms; however, executing adequate decompression without excessive facetectomy in rotated, tortuous anatomy remains challenging. Intraoperative O-arm navigation has the potential to enhance procedural accuracy of UBE decompression. This study compared the clinical outcomes and radiological parameters between O-arm navigation-assisted and conventional fluoroscopy-guided UBE decompression alone in stable ADS. METHODS: This single-center retrospective study included 63 patients with radiographically stable ADS who underwent UBE decompression alone between 2021 and 2023 (navigation, NAV: n = 34; non-navigation, NON-NAV: n = 29). This study presents details about patients' demographics, perioperative parameters, and up to 24 months follow-up outcomes. Primary endpoint was the facet preservation rate (FPR) at 1-month post-operation, quantified by CT-based 3D volumetry. Secondary endpoints included DCSA, lateral recess height/angle, dynamic angulation/slip, patient-reported outcomes (VAS/ODI), and complications. Data were analyzed using independent t-tests, Wilcoxon rank-sum tests, and repeated-measures ANOVA as appropriate. RESULTS: Operative time and length of stay were slightly shorter in NAV but not statistically different; estimated blood loss was comparable. NAV and NON-NAV groups showed significant improvements in VAS of leg/back pain and ODI at 1 month and last follow-up, without between-group differences. DCSA increased substantially in both groups (~200%-250%); but dispersion was smaller in NAV, indicating more uniform decompression. Structural preservation favored NAV (higher residual lamina-facet volumes). Segmentally, NON-NAV exhibited greater increases in dynamic angulation (8.5° ± 1.2° vs. 6.2° ± 1.4°, p < 0.001) and early slip (2.8 ± 0.8 vs. 1.8 ± 0.8 mm, p < 0.001), although radiographic instability thresholds were not exceeded. Global sagittal and coronal parameters were largely comparable between groups over time. CONCLUSION: In stable ADS, O-arm navigation for UBE decompression did not prolong operative time nor increase blood loss, and yielded tighter boundary control of decompression, higher facet preservation, and smaller segmental perturbations, while maintaining equivalent symptomatic improvement. The value of O-arm navigation lies in enabling precise and sufficient decompression while limiting medial facetectomy within stability-preserving margins.