Scoliosis and skeletal maturity: A window of opportunity for VBT treatment

vertebral body tethering (VBT) exam

Since its FDA approval in 2019, vertebral body tethering (VBT) has shown promise as a fusionless treatment for children with idiopathic scoliosis. And although more doctors are becoming aware of the procedure, they may not be familiar with the limited window of opportunity their patients have to take action.

VBT candidates have specific requirements: Because the tether is held in place with screws in the vertebral body along the outside of the scoliosis curve, it needs approximately two years of future growth to straighten the curve. That’s because the tether, tensioned on the convexity of the curve, slows the growth on the convex side of the spine and allows the concave side of the spine to catch up.

Dan Hoernschemeyer, MD
Daniel Hoernschemeyer, MD

Pediatric orthopaedic surgeon Dan Hoernschemeyer, MD, has performed thoracoscopic VBT procedures on patients at MU Health Care since 2013, and has helped advance the treatment.

“We see the best success in patients who still have some spinal flexibility and approximately two years of growth remaining,” Hoernschemeyer said. “We also know that kids who have a curve of greater than 25 degrees, when at a skeletal maturity of Sanders 1 or 2, are likely to need some form of surgical intervention to correct worsening scoliosis.”

Patients who are bracing and at risk of scoliosis progression are more likely to successfully treat scoliosis by receiving an orthopaedic evaluation before they finish growing. If scoliosis progresses as the patient reaches the end of puberty and finishes growing, VBT is no longer a treatment option. If bracing is ineffective, and the window of opportunity for VBT is missed, spinal fusion becomes the only treatment option.

Hoernschemeyer’s patients are 13.3 years old, on average, but ideal candidates can be anywhere from 8 to 16 years old. Dr. Hoernschemeyer recommends consultations for children as young as 7 to begin monitoring early and, if the family decides to proceed, everyone is ready to act once the patient is at the correct skeletal maturity stage.

“I think patient selection for VBT surgery is the most important thing that we can do as surgeons, aside from improving technique,” Hoernschemeyer said. “Skeletal maturity, and the size and flexibility of the curve are all pieces of the puzzle in deciding whether a patient is a VBT candidate.”

This window of opportunity does not stay open for long. Ideal VBT candidates have a Sanders score of 2-4, a Cobb angle between 35 and 65 degrees with an idiopathic scoliosis diagnosis from their primary care doctor or another physician.

“If you’re bracing a patient in this population, now is the time for a consultation,” Hoernschemeyer said.