Anterior vertebral body tethering for immature adolescent idiopathic scoliosis: one-year results on the first 32 patients

This retrospective chart review evaluates the clinical and radiographic outcomes of anterior vertebral body tethering (VBT) at 1-year follow-up. Anterior VBT offers a fusionless treatment option for skeletally immature patients with adolescent idiopathic scoliosis. It is a growth-modulation technique, which utilizes patients' growth to attain progressive scoliosis correction. Numerous animal models support its promise; however, clinical data remain sparse. Clinical and radiographic data were retrospectively analyzed. We reviewed 32 patients who underwent thoracic VBT with a minimum one-year follow-up. Pertinent clinical and radiographic data were collected. ANOVA, Student's t test and Fisher's exact test were utilized to compare different time points. 32 patients with thoracic idiopathic scoliosis (72 % female) with a minimum one-year follow-up were identified; mean age at surgery was 12 years. All patients were considered skeletally immature pre-operatively; mean Risser score 0.42, mean Sanders score 3.2. Patients underwent tethering of an average of 7.7 levels (range 7-11). Median blood loss was 100 cc. The mean pre-operative thoracic curve magnitude was 42.8A degrees A A +/- A 8.0A degrees which corrected to 21.0A degrees A A +/- A 8.5A degrees on first erect and 17.9A degrees A A +/- A 11.4A degrees at most recent. The pre-operative lumbar curve of 25.2A degrees A A +/- A 7.3A degrees demonstrated progressive correction (first erect = 18.0A degrees A A +/- A 7.1A degrees, 1 year = 12.6A degrees A A +/- A 9.4A degrees, p < 0.00001). Thoracic axial rotation measured 13.4A degrees pre-operatively and 7.4A degrees at the most recent measurement (p < 0.00001). One patient experienced prolonged atelectasis which required a bronchoscopy; otherwise, no major complications were observed. Our early results indicate that anterior VBT is a safe and potentially effective treatment option for skeletally immature patients with idiopathic scoliosis. These patients experienced an improvement of their scoliosis with minimal major complications. However, longer term follow-up of this cohort will reveal the true benefits of this promising technique. IV.