Emerging growth modulation techniques in treatment of adolescent idiopathic scoliosis: a meta-analysis of the outcomes and safety of anterior vertebral body tethering and ApiFix.

STUDY

DESIGN

Systematic review and meta-analysis.

PURPOSE: To systematically evaluate the effectiveness and implant failures of anterior vertebral body tethering (AVBT) and ApiFix as treatment options for adolescent idiopathic scoliosis (AIS).

OVERVIEW OF LITERATURE: We identified 27 studies involving AVBT in 1,263 patients and five studies involving ApiFix in 167 patients. The main outcomes were curve corrections, modifications in thoracic kyphosis, and alterations in lumbosacral lordosis noted at 1-, 2-, and 3-year follow-up visits. In addition, adverse events, encompassing tether breakage and reoperation rate, were meticulously documented.

METHODS

We performed a meta-analysis of the studies of adolescents with idiopathic scoliosis treated with AVBT or ApiFix. We used R software to pool data, including mean changes and event rates, and we assessed heterogeneity via the Q statistic and I 2.

RESULTS

With AVBT, the main thoracic curve improved from 46.8° to 20.6° over 1 year (53.3% reduction) and from 42.9° to 22.7° over 2 years (47.6% reduction). Thoracolumbar curves reduced by 53.8% at 1 year and by 48% at 2 years. Thoracic kyphosis did not change significantly. Tether breakage occurred in 25% of patients (up to 48% at 3 years), and 7% required reoperation. With ApiFix, at 2-3 years, the main thoracic curve improved from 45.1° to 22.7° (47.2% reduction). The pooled mean change for kyphosis was -10.0° (95% confidence interval, -35.5 to 15.4). Reoperation was necessary in 25% of cases.

CONCLUSIONS

Neither AVBT nor ApiFix achieved more than 50% curve correction. Some initial corrections were reversed, and we found no consistent evidence of growth modulation or significant sagittal improvement. Complications were substantial: tether breakage occurred in nearly half the patients with AVBT, and 25% of patients with ApiFix required reoperation. These findings raise concerns about the long-term suitability of growth modulation techniques for young patients with AIS.