Anterior Vertebral Body Tethering for Idiopathic Scoliosis Two-Year Results

Study Design. Retrospective review. Objective. To report the 2-year results of the initial cohort undergoing anterior vertebral body tethering (VBT). Summary of Background Data. Anterior VBT is a promising new technique with abundant preclinical studies but very few clinical results. It is a growth modulation technique, which utilizes patients' growth to attain progressive correction of their scoliosis. We report 2-year results of the initial cohort undergoing this procedure. Methods. After obtaining institutional review board approval, we retrospectively reviewed our first 11 consecutive patients who underwent anterior VBT with 2-year follow-up. We collected pertinent preoperative, intraoperative, and most recent clinical and radiographical data. Student t test and Fisher exact test were utilized to compare different time points. Results. Eleven patients with thoracic idiopathic scoliosis (8 females) were identified, with a mean age of 12.3 +/- 1.6 years. Preoperatively, all were skeletally immature (Sanders mean = 3.4 +/- 1.1; Risser mean = 0.6 +/- 1.1). All underwent tethering of an average of 7.8 +/- 0.9 (range: 7-9) levels, with the most proximal being T5 and the most distal L2. Preoperative thoracic Cobb angle averaged 44.2 +/- 9.0 degrees and corrected to 20.3 +/- 11.0 degrees on first erect, with progressive improvement at 2 years (Cobb angle = 13.5 +/- 11.6 degrees, % correction = 70%; P < 0.00002). Similarly, the preoperative lumbar curve of 25.1 +/- 8.7 degrees demonstrated progressive correction (first erect = 14.9 +/- 4.9 degrees, 2 yr = 7.2 +/- 5.1 degrees, % correction = 71%; P < 0.0002). Thoracic axial rotation as measured by a scoliometer went from 12.4 +/- 3.3 degrees preoperatively to 6.9 +/- 3.4 degrees at the most recent measurement (P < 0.01). No major complications were observed. As anticipated, 2 patients returned to the operating room at 2 years postoperatively for loosening of the tether to prevent overcorrection. Conclusion. Anterior VBT is a promising technique for skeletally immature patients with idiopathic scoliosis. This technique can be performed safely and can result in progressive correction.