Navigated First-Stage L1-S1 Lateral Interbody Fusion in Minimally Invasive Adult Spinal Deformity: Accuracy Rate, Surgical Time, and Technical Considerations

Abstract

BACKGROUND AND OBJECTIVES: Computed tomography (CT)–based spinal navigation improves accuracy and safety in posterior instrumentation; however, its role in multilevel lateral lumbar interbody fusion (LLIF), particularly extending to the lumbosacral junction in adult spinal deformity, remains incompletely defined. Existing studies primarily evaluate short-segment degenerative cases, with limited data addressing full lumbosacral constructs in patients with complex deformity. The objective of this study was to evaluate radiographic accuracy, operative efficiency, and perioperative complications of navigation-assisted first-stage LLIF from L1 to S1 for minimally invasive treatment of adult degenerative scoliosis (ADS). METHODS: A retrospective review was performed of 12 consecutive ADS patients undergoing first-stage navigated multilevel oblique lateral interbody fusion from L1 to L5 with or without lateral anterior lumbar interbody fusion at L5–S1, followed by second-stage robotic-assisted minimally invasive posterior fixation. Cage position was assessed using intraoperative fluoroscopy, postoperative CT, and radiographs with a quartile-based classification (quartiles 1-3 defined as accurate). Operative time, blood loss, spinopelvic parameters, and complications were recorded. RESULTS: Fifty-five cages were placed across, on average, 4.3 levels per patient. Fifty of 55 cages (90.9%) were positioned within quartiles 1-3; none were placed anterior to disk space or breached the posterior canal. The mean operative time was 328.0 minutes, and the mean estimated blood loss was 87.4 mL. Transient approach–related neurological symptoms occurred in 6 patients (50.0%), most commonly left thigh pain, all resolving without intervention. No vascular injuries were observed. Significant improvements were observed in Cobb angle (Δ27.1°,= 7.53 × 10), L4–S1 lordosis (Δ8.4°,= .011), pelvic tilt (Δ8.5°,= 8.46 × 10), pelvic incidence–lumbar lordosis mismatch (Δ18.7°,= 2.96 × 10), T4 pelvic angle (Δ8.2°,= .007), and T4–L1 pelvic angle mismatch (Δ4.7°,= 7.53 × 10). CONCLUSION: Navigation-assisted multilevel LLIF extending to L5–S1 demonstrates high placement accuracy, meaningful deformity correction, and acceptable morbidity in ADS. These findings support feasibility and safety of CT-based navigation for multilevel lateral surgery in spinal deformity patients.