Anterior Vertebral Body Tethering for Treatment of Idiopathic Scoliosis in the Skeletally Immature Results of 112 Cases

Study Design. Prospective case series. Objective. Determine the efficacy of anterior vertebral body tethering (AVBT) in skeletally immature patients. Summary of Background Data. The value of AVBT is currently unclear given the paucity of available data. Methods. Consecutive skeletally immature patients with idiopathic scoliosis were treated with AVBT between 2012 and 2018 by one of two surgeons working at two independent centers and followed up for >2 years. Data were collected prospectively and supplemented retrospectively where necessary. Outcomes were measured preoperatively, at first erect radiograph (FE), 1-year postoperatively and at most recent follow up (FU). Results. One hundred twelve patients underwent 116 primary tethering procedures (108 thoracic and eight lumbar tethers). Four patients had primary tethering of both lumbar and thoracic curves. At surgery mean age was 12.7 +/- 1.4 years (8.2-16.7) and Risser 0.5 +/- 0.9 (0-3). Follow up was mean 37 +/- 9 months (15-64). Preoperative mean coronal Cobb angle of the 130 tethered curves was 50.8 degrees +/- 10.2 (31-81) and corrected significantly to 26.6 degrees +/- 10.1 (-3-61) at FE radiograph (P<0.001). Further significant improvement was seen from FE to 1-year, to mean 23.1 degrees +/- 12.4 (-37-57) (P<0.001). There was a small but significant increase between 1-year and FU to 25.7 degrees +/- 16.3 (-32-58) (P<0.001), which appeared to reflect tether breakage. Untethered minor curves were corrected from 31.0 degrees +/- 9.5 (3-57) to 20.3 degrees +/- 10.3 (0-52) at FU (P<0.001). Rib hump was corrected from 14.1 +/- 4.8 (0- 26) to 8.8 degrees +/- 5.4 (0-22) at FU (P<0.01). Twenty-five patients (22%) had 28 complications. Fifteen patients (13%) requiring 18 revision operations including six completed and one awaited fusions. Conclusion. AVBT of immature cases is associated with satisfactory deformity correction in the majority of cases. However, complication and revision rates suggest the need for improved implants and patient selection. Long-term follow-up remains crucial to establish the true efficacy of this procedure.