Vertebral body tethering compared to posterior spinal fusion for skeletally immature adolescent idiopathic scoliosis patients: preliminary results from a matched case-control study.

Purpose: Direct comparisons between vertebral body tethering (VBT) and posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) are limited. We aimed to evaluate 2-year results of VBT and PSF to report comparative outcomes.

Methods: 26 prospectively enrolled VBT patients were matched 1:1 by age, gender, Risser sign and major curve magnitude with PSF patients. At a minimum 2-year follow-up, surgical results and radiographic outcomes were reviewed.

Results: Operative time, anesthesia time, blood loss, and length of stay were significantly lower in the VBT group (< 0.001, p = 0.003, p < 0.001, p < 0.001, respectively). The major curve at 2 years was corrected by 46% in the VBT group vs. 66% in the PSF (p = 0.0004). Success following VBT, defined as no fusion surgery and Cobb angle < 35° at the 2-year follow-up, was seen in 20 VBT patients (77%) (p = 0.0003) and correlated with mean Cobb angle of < 35° on 3-month imaging. 12 VBT patients (46%) showed curve improvement over time, and those patients had significantly lower mean Cobb angle on the 3-month radiograph than non-modulators (23° vs 31°, p = 0.014). At 2 years, cord breakage occurred in five patients (19%). By 2 years, three VBT patients developed complications (2 pleural effusion and 1 overcorrection needing return to OR). In contrast to PSF, growth continued at T1-T12 (mean 13 mm) and over the instrumented levels (mean 10 mm) following VBT, compared to no growth over instrumented segments in the fusion cohort (p = 0.011, p = 0.0001).

Conclusion: In Sanders stages 3 and 4 patients treated in the USA, Cobb angle < 35° on 3-month imaging was associated with success at the 2-year follow-up. Curve correction was superior in the PSF group with 96% achieving curve correction to < 35° vs. 77% of the VBT patients. Cord breakage was noted in 19% of VBT patients at the 2-year follow-up. Three patients developed complications in both the VBT and PSF cohorts.

Level Of Evidence: Level II (prospective study with matched retrospective comparison group).