Vertebral Body Tethering in 49 Adolescent Patients after Peak Height Velocity for the Treatment of Idiopathic Scoliosis: 2–5 Year Follow-Up

Abstract

Vertebral Body Tethering (VBT) is a non-fusion surgical treatment for Adolescent Idiopathic Scoliosis (AIS) that elicits correction via growth modulation in skeletally immature patients. VBT after peak height velocity is controversial and is the subject of this study. A retrospective review of Risser 3–5 AIS patients treated with VBT, and min. 2-year FU was performed. Pre to post-op changes in clinical outcomes were compared using Student’s t-test or the Mann-Whitney test. A total of 49 patients met criteria, age 15.0 ± 1.9 years, FU 32.5 ± 9.1 months. For thoracic (T) major curvatures, T curvature improved from 51.1 ± 6.9° to 27.2° ± 8.1° (p < 0.01) and TL from 37.2° ± 10.7° to 19.2° ± 6.8° (p < 0.01). For thoracolumbar (TL) major curvatures, T improved from 37.2° ± 10.7° to 18.8° ± 9.4° (p < 0.01) and TL from 49.0° ± 6.4° to 20.1° ± 8.5° (p < 0.01). Major curve inclinometer measurements and SRS-22 domains, except activity, improved significantly (p ≤ 0.05). At the latest FU, one (2%) patient required fusion of the T curve and revision of the TL tether due to curve progression in the previously uninstrumented T curve and tether breakage (TB) in the TL. Twenty (41%) patients experienced TB. VBT in AIS patients with limited remaining skeletal growth resulted in satisfactory clinical outcomes at the latest FU.

Vertebral body tethering: An alternative to posterior spinal fusion in idiopathic scoliosis?

“…Hegde et al reported on 10 female skeletally mature patients (Risser 4 and Sanders 7) after minimum 1-year follow-up and reported improvement in Cobb's angle from 52° to 15.9°. In skeletally mature patients, VBT is thought to improve the deformity when maximal intraoperative correction is done because growth potential is limited and thus less predictable growth-guided modulation ( 8 , 15 ). Miyanji et al published on 55 immature patients Risser 0.5 showing clinical success in 77% and 8% insufficient correction requiring conversion to PSF ( 19 ).…”

“…Miyanji et al published on 55 immature patients Risser 0.5 showing clinical success in 77% and 8% insufficient correction requiring conversion to PSF ( 19 ). Alanay et al reported on mature cohort of Sanders score 6–7 with 100% success, 55% correction and residual curve (9°–27°) at 20 months and Meyers et al reported on 49 mature patients with 76% success, 41% tether breakage and 2% revision with PSF at 32.5 months ( 8 , 26 ). Figures 4 – 6 showcase a 14-year-old female (Sanders 7) that underwent T12-L4 anterior tethering with correction of the curve from 42° to 17° postoperatively and the patient being well balanced at 6-months post surgery.…”

“…Yet still, there exists a risk of overcorrection, construct breakage or failure of procedure which require revision and at times conversion to PSF. Successful VBT operation are seen with smaller preoperative major curve and curves that are more flexible ( 8 , 16 ) and neither age nor Risser staging contributed to success or failure of the procedure ( 8 ).…”

“…As such, decreasing both anterior and lateral growth through applying compression on the convex and anterior sides of the vertebrae while promoting and allowing growth on the concave and posterior aspects would result in spinal realignment based on Hueter-Volkmann principle ( 5 ). The success of VBT is assessed clinically through radiographic findings and durability of outcomes associated with pain reduction and improvement of body image ( 8 ).…”

Incidence of Tether Breakage in Anterior Vertebral Body Tethering

“…3 Tether breakage is one of the most common occurrences of AVBT, 4 but the reported incidence varies significantly between studies from 3.3% to 52%. 1,[5][6][7][8][9][10][11][12] The tether tends to fail between levels 3 and failure can be identified radiographically. [1][2][3][6][7][8]11,[13][14][15] An example of a patient with suspected tether breakage is shown in Fig.…”