Apical vertebral modulation with active apex correction technique for congenital early-onset scoliosis: a retrospective study

Study Design: Retrospective, single-center study. Purpose: This study aimed to evaluate whether active apex correction (APC) enables effective modulation of the apical vertebrae in congenital early-onset scoliosis (EOS). Overview of Literature: APC is a posterior tethering technique that incorporates guided growth principles for the treatment of EOS. The procedure involves the strategic placement of tethering pedicle screws on the convex side of the apical region to achieve controlled modulation of vertebral growth. Methods: This retrospective study included 10 patients with congenital EOS who underwent APC as the primary surgical procedure. Preoperative and final follow-up assessments were performed using EOS imaging to measure concave and convex vertebral heights at the apical region and evaluate growth modulation. Patients were excluded if follow-up was <2 years, if apex modulation data were incomplete, or if APC was not the index procedure. Results: The mean age at surgery was 8.2±2.39 years, and the mean postoperative follow-up was 2.3±0.48 years. The concave-toconvex vertebral height ratio at the apical region showed significant changes. At proximal apical vertebrae (A1), the ratio increased from 0.75 preoperatively to 0.84 at final follow-up (p<0.05). At the middle vertebrae (A2), the ratio improved from 0.71 to 0.78 (p<0.05). At the distal vertebrae (A3), the ratio increased from 0.77 to 0.81, although this change was not statistically significant (p>0.05). In contrast, untethered control vertebrae demonstrated a stable mean concave-to-convex height ratio. Conclusions: APC appears effective in EOS, enabling targeted modulation of the three apical vertebrae through guided growth principles. This technique enables controlled correction of the spinal apex and represents a promising growth-preserving alternative for apical deformity management.