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 centres and followed up for >2 years. Data was 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:

112 patients underwent 116 primary tethering procedures (108 thoracic & 8 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 to 3). Follow up was mean 37 ± 9 months (15-64). Preoperative mean coronal Cobb angle of the 130 tethered curves was 50.8° ± 10.2 (31 to 81) and corrected significantly to 26.6° ± 10.1 (-3 to 61) at FE radiograph (p < 0.001). Further significant improvement was seen from FE to 1-year, to mean 23.1° ± 12.4 (-37 to 57) (p < 0.001). There was a small but significant increase between 1-year and FU to 25.7° ± 16.3 (-32 to 58) (p < 0.001), which appeared to reflect tether breakage. Untethered minor curves were corrected from 31.0° ± 9.5 (3 to 57) to 20.3° ± 10.3 (0 to 52) at FU (p < 0.001). Rib hump was corrected from 14.1 ± 4.8 (0 to 26) to 8.8° ± 5.4 (0 to 22) at FU (p < 0.01)). Twenty-five patients (22%) had 28 complications. Fifteen patients (13%) requiring 18 revision operations including 6 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.Level of Evidence: 3.