Vertebral Body Tethering (VBT)
What is Vertebral Body Tethering (VBT)?
Vertebral Body Tethering (VBT) is a promising new approach to the surgical treatment of adolescent idiopathic scoliosis (AIS) in growing children whose scoliosis continues to progress despite bracing. VBT can be used instead of the spinal fusion surgery for some children with idiopathic scoliosis.
This treatment changes the growth of the spine to correct scoliosis. It allows the spine to continue to grow during this treatment.
During this surgery, a strong cord called a tether is attached to the spine. The cord causes the spine to straighten as a patient grows. This cord is flexible, so patients with vertebral body tethering can keep some flexibility in their spine. This is a major advantage of this procedure.
This technique was approved by the FDA (American Food and Drug Administration) in August 2019.
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How is Vertebral Body Tethering (VBT) performed?
This particular surgical technique takes advantage of the future growth of the spine, which is not disturbed through surgery, to lead to further correction of the lumbar and thoracolumbar scoliosis over time (Fig. 1 & 2).
The philosophy behind VBT is to slow the growth of the convex side of the spine so that the opposite concave side can grow to balance the difference, something that leads to spinal alignment (Fig. 6).
During the surgery, the smallest possible incisions are made on the patient’s side using a thoracoscopic or minimally invasive technique. Through these small incisions, titanium metal screws are placed along the vertebrae in the anterior portion of the spine (Fig. 5) that curves outward (at a safe distance from the spinal cord and nerves).
After the screws have been placed and confirmed by both direct visualization and specialized radiography a strong flexible cord is attached to the screws (Fig. 3). It is then fixed to each screw (at each level) after first being stretched to correct the curvature (Fig. 4 & 5).
When the application is complete, a final X-ray is taken, a chest drain is placed to drain fluid and air, and the incision is sutured. Over time, as the child continues to grow and his/her spine lengthens, it slows down the growth on the curved side of the spine, facilitating the growth of the other concave side by balancing the difference.
Thus, scoliosis is corrected, at an extent, through surgery, while the rest of the correction can be achieved over time as the child grows.
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What are the main indications for Vertebral Body Tethering (VBT)?
This particular surgical technique corrects scoliosis by guiding the growth of the spine over time. Consequently, it is indicated in children and adolescents who have not yet reached maximum growth.
The ideal age for a child to undergo VBT is usually between 10 to 16 years old, although each case is different. Indications have now been extended to include younger children as well as those who have reached skeletal maturity and would prefer to avoid traditional posterior spinal fusion.
Scoliosis curves between 40-70 degrees and in some cases, even greater, can potentially be treated with this technique. At the same time, VBT is mainly indicated for children with idiopathic scoliosis that is not related to neurological diseases or other spinal deformity or injury.
Postoperative course
The incisions are performed in a way that does not cut the muscles, making recovery easier. Recovery is similar to that of a posterior spinal fusion except for a few differences. Patients typically will have a chest tube or drain after a thoracic VBT that can remain in place for 2-3 days. The hospital stay is between 3-5 days and similar pain medications are used as with a posterior spinal fusion. After 6 weeks, VBT patients are allowed to return to their daily activities.
The Advantages of Vertebral Body Tethering (VBT)
The specific surgical technique is important to be carried out by a specialized Spine Surgeon, who has significant experience in this type of surgery and especially in anterior approaches to the spine. If VBT is successfully performed, it offers significant benefits to the patient, as:
- VBT is typically a one-time surgery with little need for surgical upgrades.
- With no fusion of the vertebrae required, the spine retains its flexibility and room for growth.
- Post-operative recovery time is significantly reduced as the incisions do not injure the muscles.
- There is no need to place a back brace after the operation.
- The surgery materials remain permanently attached to the child’s spine, unless a problem arises postoperatively.
- Flexibility in the spine allows the patient to return to sports or other active hobbies.
- Minimally invasive techniques lead to shorter hospital stays and abbreviated recovery times.
- The flexible cord will immediately generate a noticeable difference in posture after surgery.
- Many patients are up and walking on the same day as the procedure.
Is VBT an experimental procedure? Is there a chance that my scoliosis is not being treated properly with this method?
This procedure is not experimental. It is certainly a recent procedure and therefore we do not have the data we have for the classic spinal fusions in the long run (about 20 years). But it is an approved method by the strictest regulatory organizations worldwide, such as FDA, with very good results over 5 years.
The most common problem we encounter with this technique is cord breakage. In this case, it may be necessary to replace it (a surgical procedure clearly less serious than the first). In many of these cases, cord replacement is not necessary.
In the worst (and rarer) scenario, where scoliosis is not properly treated with this method, the classic posterior instrumented correction and fusion is performed.
