Which Patients With Scoliosis Are Best for Vertebral Body Tethering?

Vertebral body tethering (VBT) is a relatively new technique for treating progressive scoliosis in children. Instead of conventional spinal fusion surgery, which significantly reduces spinal mobility, VBT preserves mobility while guiding the spine into alignment as the child grows.

The surgical treatment has been offered at Cleveland Clinic since 2019.

“The concept of VBT is similar to growth modulation in the extremities, which may be more familiar to pediatricians,” says pediatric spine surgeon Ryan Goodwin, MD, Director of the Center for Pediatric Orthopaedics and Spine Deformity at Cleveland Clinic. “With growth modulation — also called ‘guided growth’ — we put a device around a growth center in a child’s leg, for example, so it grows from crooked to straight. VBT works the same way in the spine. We put forces around growth centers on one side of the spine so the other side can catch up.”

How VBT works

Unlike spinal fusion, which requires a large incision on the patient’s back, VBT is minimally invasive, performed through tiny incisions on one side of the child’s chest.

The anesthesia team positions the patient on their side (convex spinal curve up) and then selectively deflates one lung to facilitate visualization of the front of the spine. Screw-like devices are inserted into each vertebra on the convex side of the curved spine. The screws then are tethered together with a flexible cord.

The tension of the cord applies force to the patient’s spinal growth centers, causing them to grow slower so the untethered (concave) side of the spine can catch up as it grows normally — usually over 12-24 months. The cord usually does not need to be adjusted or removed. As long as the patient achieves spinal correction or reaches skeletal maturity with a curve less than 40 degrees, the VBT screws and cord remain in place.

“Patients typically leave the hospital within 24 hours and require very few narcotics to control pain,” Dr. Goodwin says. “The morbidity of the procedure is very low compared to spinal fusion, where the patient is in the hospital for two to three days. Patients can return to their regular activities, even running, jumping, flipping and riding roller coasters, six weeks after VBT. It takes longer to return to school, sports and other activities after spinal fusion.”

When to recommend VBT

The ideal candidates for VBT are patients who have:

• Progressive idiopathic scoliosis
• Spinal curves between 35 degrees and 65 degrees
• Skeletal growth remaining

Patients usually are between ages 10 and 15. However, skeletal age (as determined by hand X-rays, using the Sanders staging system) is more important than chronological age.

“If the patient’s growth centers are completely closed or if their spine has a curve more than 65 degrees, spinal fusion may produce better outcomes,” Dr. Goodwin says. “VBT also may not be ideal for younger patients who have a great deal of skeletal growth remaining. Overcorrection can be a risk for them.”

Still, Dr. Goodwin reinforces that VBT is the best surgical option for select patients because it preserves motion and prevents the stress that fusion can place on spinal disks. That stress can lead to degenerative arthritis later in life.

“For the right patients, VBT is more beneficial in the short term as well as long term,” he says. “And it preserves the option for spinal fusion later, if needed.”

More pediatricians should know

Because VBT is so new, long-term data are still being collected. Dr. Goodwin’s team is preparing to publish outcomes of the more than 100 cases managed to date at Cleveland Clinic.

“Easily 85% of our patients do well after a single operation,” he says.

He continues to raise awareness of VBT, especially among pediatricians.

“Most pediatricians understand the importance of treating progressive scoliosis, but many don’t know about VBT,” Dr. Goodwin says. “I want them to know that spinal fusion is no longer the only surgical treatment option. Some kids can benefit from motion-preserving growth modulation. However, they need to be referred for evaluation while they are still growing, so we don’t miss the window of opportunity.”