The gold standard for adolescent scoliosis deformity correction, posterior spinal fusion, may be on its way to being dethroned by a non-fusion technique that is gaining popularity.
A recent retrospective study published by surgeons at the University of Missouri School of Medicine and MU Health Care in The Journal of Bone and Joint Surgery titled, “Anterior Vertebral Body Tethering for Adolescent Scoliosis with Growth Remaining: A Retrospective Review of 2 to 5-Year Postoperative Results” found that vertebral body tethering may be a reliable treatment for adolescent scoliosis in children who are still growing.
Vertebral body tethering (VBT), is just like it sounds, a polyethylene tether is connected to screws anchored in vertebral bodies along the convex side of a scoliotic curve in children still growing. The tether is tensioned during surgery and as the spine grows, effectively pulling the spine into alignment.
Risks of the procedure include implant failure (cable breakage), over-correction, and some patients eventually progress to needing fusion anyway. The procedure has been used in humans for about a decade, with the first case report published in 2010. However, the procedure was performed using materials off-label as an FDA approved VBT system was not available in the U.S. until 2019 when Zimmer Biomet received a humanitarian device exemption (HDE) for its VBT system called The Tether™. The procedure has been the subject of debate at international spine conferences, with some suggesting that most patients will eventually need fusion anyway making VBT an unnecessary additional surgery.
The present study followed patients for 2-5 years and over that period of time found that posterior spinal fusion was not required in 93% of patients. However, the surgeons who compiled the data suspected that the tether had broken in nearly half of patients and 29% of those patients underwent a revision procedure. Two patients (7%) required posterior spinal fusion surgery.
One of the study’s conclusions was that extended follow-up is necessary to determine the long-term ability of tethering to avoid fusion in patients.
The principal investigator, Dan Hoernschemeyer, M.D., has used the procedure in over 85 patients.
He explained the study and benefits of the procedure in a statement from the University: “If the child’s spine has more than 45 degrees of scoliosis and still has some growth remaining, VBT is a way to correct the scoliosis, preserve motion and modulate normal growth instead of fusing it. Our study examined the radiographic and clinical outcomes of idiopathic scoliosis patients with various curve patterns treated with VBT.”
He summarized the conclusions of the study by saying, “While the exact role of VBT in the management of adolescent scoliosis continues to be defined, the data from this study supports the fact that this surgical procedure should be considered as a treatment option for children with scoliosis and an alternative to fusion.”
