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Anterior Vertebral Body Tethering (AVBT): Technique for Idiopathic Scoliosis without fusion

Anterior Vertebral Body Tethering is a way of using growth to control the curvature. We do this in children with angulation of the legs very successfully and lots of work is underway to develop effective, predictable ways of doing this in the spine. The technique has largely replaced another means of growth modulation called anterior vertebral stapling. In anterior vertebral tethering, screws are placed in the front of the spine and attached to each other with a flexible, polyethylene terephthalate (PET) cable on the convexity of the curve. This is still a new technology with unknown long-term outcomes. Early results have been promising though far from perfect, and there is great hope that this will evolve to be an option for larger groups of patients with scoliosis and significant growth remaining. Tethering is an option for children with curves less than 65 degrees with significant growth remaining.

What Are the Indications of Vertebral Body Tethering?

The indications for this technique is that patients that are skeletally immature (>8 years old, Sanders ≤ 4) with a high risk of progression. The curve size can be from 40-65 but it must be flexible. We determine the curves flexibility with bending xrays.

While FDA approved this technique in 2019, this is still a new technology with unknown long term outcomes. The decision between fusion and vertebral body tethering is still evolving and is a case-by-case discussion and decision between the surgeon and the family. Please see A Tale of Two Spines (PPT) for more information about Fusion vs. VBT (tethering). In the right setting though and in the right patient, AVBT may be the best option.

AVBT Anterior Vertebral Body Tethering xray

AVBT – Anterior Vertebral Body Tethering xray

AVBT Resources

A Selection from A Tale of Two Spines: Deciding Between Vertebral Tether and Fusion

When your adolescent child has scoliosis that is in the surgical range there are currently two options in how to address the curve:

  • The traditional surgery for scoliosis is called a posterior spinal fusion and instrumentation—or PSIF. This procedure uses a spinal rod placed in the back part of the spine.
  • The other option which is anterior vertebral body tethering (AVBT) is where the tether uses a flexible cord which is placed from the front part of the spine only on the convexity of the curve. This allows correction of the scoliosis but also continued growth on the opposite (concave), untethered side.
Fusion vs tethering example

Fusion vs Vertebral Body Tethering hardware comparison

Here are the differences between the two procedures to help you make an informed decision about what is best for your child.

  • An Anterior Vertebral Body Tethering (AVBT) Candidate:
    • Curves 40-60 degrees
    • Flexible curves
    • Compensatory Curve smaller than 45 degrees
    • Mild amount of rotation
    • Skeletally immature: Risser 0–3; Sanders 2–5
    • Operation is usually thoracoscopic (minimally invasive)
    • Length of hospital stay 2 days
    • 10% Risk of Reoperation
    • Little to no loss of flexibility
    • Back to sports at 6 weeks
  • A Fusion Candidate:
    • Curve >50 degrees
    • Flexible or inflexible curves
    • Any size compensatory curve
    • Mild to Severe Rotation
    • Skeletally immature or mature: Risser 0–5; Sanders 3–8
    • Operation is through a 10 cm incision
    • Length of hospital stay 3-4 days
    • 2% Risk of Reoperation
    • Possible loss of flexibility depending on lowest level fused
    • Back to sports 6 weeks

Additional Resources:

Please see the full PowerPoint presentation: A Tale of Two Spines (PPT) for more information about Fusion vs. Anterior Vertebral Body Tethering (tethering).

Watch the videos, below:

The Benefits of Vertebral Body Tethering (VBT) | ZimVie

What is The Tether™ Vertebral Body Tethering System? | ZimVie

Pediatric Orthopaedic Spine Surgery Pre-Op Class