Vertebral Body Tethering
What is Vertebral Body Tethering (VBT)?
Vertebral Body Tethering (VBT) is a form of scoliosis surgery that aims to preserve spinal mobility. Whereas traditional scoliosis surgeries have relied on spinal fusion, VBT uses a fusionless system to affect change.
But, what makes fusionless the better option? To answer this question, let’s start by taking a look at how fusion surgeries work. During a fusion procedure, your doctor fixes the angle of your spine by:
- Removing any damaged discs
- Using hooks, rods, and screws to realign your spine
- Inserting a bone graft into the interbody space (The interbody space simply refers to the gap where your disc once was.)
As that bone graft grows, the two target vertebrae will fuse together. Although this creates a “straighter” spine, you have achieved this correction by removing a joint from your backbone. Unfortunately, this also means that you will lose a small amount of movement in your back. If you need to have more than two vertebrae fused, then the amount of lost flexibility can add up quickly.
Not many patients find this idea exciting. Especially active young patients who play sports. So, VBT was invented to change the game. And, the rest is now history.
How Does Vertebral Body Tethering (VBT) Work?
VBT works according to the Hueter-Volkmann Law. This rule states that compressive forces which apply pressure to the spine slow down bone growth. So, VBT uses this idea to achieve growth modulation. By “growth modulation,” we mean that that the tethering procedure causes the spine to grow along a healthier path.
Because surgeons primarily use this procedure for patients who have yet to reach skeletal maturity, growth modulation is possible. In fact, managing the angle of your scoliosis during growth spurts is key to treating idiopathic scoliosis.
If you need VBT, your surgeon will approach your spine from the posterior (or back) side. However, your doctor will make the incision itself under your armpit. (As of now, anterior scoliosis correction with VBT has yet to receive approval from the FDA.) At this point, your surgeon may also insert a scope to help view the tender tissues of your spine.
With your thoracic spine in plain sight, your surgeon will apply titanium screws to the convex side of your curve. (This procedure can also be used to correct your lumbar spine, but in this case, your surgeon must make the incision lower.) These screws will dot the entire length of the convex curve, like metal brackets on braces. Next, your doctor will thread a flexible cord through each of the screws. When the cord is pulled taut, compressive forces will be applied to your spine.
The pressure from the cord causes the vertebrae to grow denser and more slowly on the convex side of the curve. However, the concave side of your spine will continue to grow at a normal rate. The end product of all of this? A backbone that rights its own spinal curvature as it grows.
Do I Qualify for Vertebral Body Tethering (VBT)?
Patients who have yet to reach skeletal maturity (a 0-2 on the Risser scale) make the best candidates for VBT. (The Risser scale uses the degree of hip bone development to estimate the level of a child’s skeletal maturity. Lower numbers on the scale represent less maturity.)
However, even some adults (Risser scale 3-5) will witness improvements in their spines after VBT. For this to be the case, the spine must be flexible instead of rigid. Furthermore, VBT works best for patients who have between 35 and 70 degrees of scoliosis. If you have <35 degrees, then your doctor will prescribe more conservative methods, like bracing. If you have >70 degrees, then your condition will likely require a spinal fusion or osteotomy to fix.
Unfortunately, not all patients will qualify for VBT. If your child is younger than 10 years old, then your doctor must decline to perform the procedure.
To find out if you–or your child–qualifies for VBT, contact a spine surgeon whom you trust. Dr. Jason Lowenstein, board-certified scoliosis surgeon, has earned over a decade of recognition for his pediatric scoliosis correction techniques. Because your family deserves only the best, contact the Lowenstein team today!