Functional, Radiographic, and Patient-Reported Outcomes of Hybrid Fixation Versus Posterior Long Fusion for Double-Major Adolescent Idiopathic Scoliosis

Abstract

Background: Posterior spinal fusion (PSF) provides reliable deformity correction for adolescent idiopathic scoliosis (AIS); however, it reduces lumbar mobility because of the fusion of motion segments. Hybrid fixation, which combines thoracic PSF with thoracolumbar/lumbar vertebral body tethering (VBT), aims to preserve lumbar function while maintaining satisfactory deformity correction. Methods: This retrospective comparative cohort study included 66 adolescents with double-major AIS treated with hybrid fixation (n = 30) or posterior long fusion (n = 36). Radiographic outcomes, lumbar flexibility, sagittal range of motion (ROM), lumbar core muscle strength (LCMS), SRS-22r Function scores, complications, and revision surgery were assessed after a minimum follow-up of 24 months. Multivariable regression analyses were used to identify independent predictors of postoperative functional outcomes. Results: Both procedures achieved excellent correction of the main thoracic curve and satisfactory global spinal alignment. Posterior long fusion provided greater thoracolumbar/lumbar curve correction (p < 0.001), whereas hybrid fixation resulted in significantly better lumbar flexibility, sagittal ROM, and LCMS (all p ≤ 0.006). Revision surgery was more frequent after hybrid fixation (20.0% vs. 0%, p = 0.007), primarily because of tether-related complications. Conclusions: Hybrid fixation better preserves objective lumbar function than posterior long fusion while maintaining satisfactory deformity correction in adolescents with double-major AIS. These functional benefits should be balanced against the higher revision burden, supporting individualized treatment selection and shared decision-making when considering motion-preserving surgical strategies.