Fusionless scoliosis tethering (otherwise known as vertebral body tethering or VBT) is a less invasive surgical procedure that has been used for the past 7 years by a select number of Orthopedic surgeons. While still a highly invasive surgical procedure, as all spinal surgeries are, it does offer some significant advantages over the more widely used spinal fusion for scoliosis procedures.
Please note, as with all surgical procedures, there are risks and complications associated with a certain percentage of cases and scoliosis tethering procedures should only be considered as an alternative to fusion surgery for scoliosis. At the time this article is being written, surgical tethering for scoliosis is not currently FDA approved and being offered as an “off label” alternative intended for surgical intervention for adolescent idiopathic scoliosis.
Less Blood Loss and Faster Recovery Time with Scoliosis Tethering
Many of the scoliosis tethering procedures are done endoscopically, meaning the actual surgery is performed via an endoscope, and do not require an open back incision. This means a 4-6 inch scar under one of the arm pits (usually the right side), rather than a full spine incision down the middle of the back. Cosmetically, this is obviously desirable, but clinically it means a lot less blood loss (and little or no blood transfusions), less risk for infection, and a much faster recovery time since less muscle, bone, tendon, tissues are damage during the procedure. Clearly these advantages are significant to clinical outcomes, but can and do have a positive effect on the financial burden of surgical intervention for scoliosis
Scoliosis Tethering can be used at Younger Ages to “Guide Spinal Growth”
Scoliosis curve progression is typically seen during periods of rapid growth, particularly in female patients, and unbalanced pressure on the vertebrae may cause uneven growth of the spinal bones. For centuries, yes centuries, doctors have attempted to “guide spinal growth” in scoliosis patients with rigid braces. While it sounds good in theory, practical application of applying pressure to the spine through the muscles, organs, lungs, ect with a brace have proven rather ineffective and psychologically traumatizing for patients. The end results indicate wide spread use of braces for scoliosis do not reduce the number of patients for whom surgical fusion is recommended.
The pressure place on the convexity (outside part) of the spinal curvature by the scoliosis tethering procedure works to re-balance the pressure being placed on the vertebrae during growth and can effectively guide spinal growth during growth spurts. Some concerns and complications have arose leading to unintended spinal compensation patterns, but innovative new rehabilitation programs are being developed to address these issues.
Spinal Motion Sparing
Unlike multiple level spinal fusion, tethering for scoliosis does not create intersegmental fusion and has very little negative impact on spinal biomechanics. The spine is composed of 24 individual segments that work together in a lever arm fashion to produce the torque force that drives the pelvis and shoulder girdles to provide human locomotion (walking/running). Fusion surgeries in scoliosis patients often involved 6-8 segments and essentially meld them all together into one long bar of bone. This has a profound impact on the spinal biomechanics and often leads to many pain syndromes as a result of dis-coordinated spinal muscle firing patterns leading to inflammation and muscle spasms.
Vertebral Body Tethering (VBT) is a relatively spinal motion sparing procedure that still allows for almost all normal spinal biomechanics and an almost full range of spinal motion as well. Although long term data isn’t yet available, it is likely the long term pain syndromes associated with tethering for scoliosis should be much lower than those found in long term post fusion treated scoliosis patients.
Less Hardware = Less Complications
Spinal fusion procedures being utilized in the treatment of scoliosis require a lot of surgical hardware. Very long screws, hooks, long rods, and dissection of the entire posterior spinal joint system in order to install the hardware. As everyone knows, the more hardware, pieces, and parts, the more likely the chance for complications and breakage in the future, which is also supported by the published long term data on traditional scoliosis fusion procedures.
Scoliosis tethering require much less hardware and no destruction of any spinal joint systems. In fact, the only “moving parts” are a nylon cord that is secured at each and every spinal level making systemic failure of the tether virtually impossible. As stated earlier in this article, long term data on vertebral body tethering (VBT) isn’t yet available, but the minimal used of hardware, lack of invasive spinal joint dissection, and stress being place on a nylon cord, rather than metal rods, is widely expected to outperform the long term complication rates seen in post fusion treated patients.
The treatment of adolescent idiopathic scoliosis has and continues to be a challenge for all healthcare providers who seek to help patients overcome it. Passive approaches implemented via braces and fusion surgeries have not proved an effective treatment model given the unpredictability of results and reality of long term complication rates. Less invasive, spinal motion sparing approaches like tethering surgery for scoliosis are a welcome and necessary step forward in an effort to convert the current scoliosis treatment model into an active approach which may prove more effective with less risk of unintended long term complications. It is the hope and expectation, that more Orthopedic surgeons will begin to offer and recommend vertebral body tethering as the primary recommendation as an alternative to spinal fusion surgery as long term data becomes available and the FDA grants full approval in the next couple of years.