Two Scoliosis Surgery Options that Aren’t Fusion

Two procedures approved by the FDA in 2019 provide new options for people in need of surgery for scoliosis. Learn more about these minimally invasive, motion-sparing procedures from our expert.

Having a curved spine is normal, if they’re the right curves. There are two inward bends (called lordosis) at the neck and the lower back, and one outward curve (kyphosis) in the upper back. Side-to-side curves, however, aren’t supposed to be there. That’s scoliosis, and it’s one of the more common abnormal spine curvatures.

Child preparing for non fusion scoliosis surgeryFusion is not the only option anymore for scoliosis surgery.

Spine specialists use the angle of the lateral (side) curvature in scoliosis to recommend different treatment options. With a mild enough angle, many spine specialists prefer to just monitor the condition to make sure it doesn’t get worse or start causing symptoms. For slightly more extreme curves, there are a number of nonsurgical options for treatment. And, while surgery is not indicated for all cases of scoliosis, if the curvature progresses or is large enough, your doctor may recommend surgery.

Spinal Fusion for Scoliosis

Fusion has been the gold standard treatment for scoliosis surgery for the past century, and modern fusion procedures have reliable outcomes with low complication and re-operation rates. Spinal fusion is, essentially, a biological welding together of spinal vertebra, the building blocks of the spine.

However, it causes loss of motion and flexibility in fused portions of the spine as well as potential loss of ability in sports and activities requiring flexibility such as dancing, swimming, gymnastics, tennis and golf. Possible long-term impacts of fusion include:

Fusion is no longer the only game in town when it comes to surgery. You now have non-fusion choices for surgery, if you or your child’s scoliosis is severe enough to warrant it. The benefits of non-fusion surgical options include greater preservation of flexibility and mobility, and the ability to continue in high impact sports. Long-term, there is the potential for less degenerative disc disease, neck and back pain compared to fusion.

There are currently two FDA-approved options for non-fusion correction, both approved in August 2019: The Tether and ApiFix. These procedures offer a more rapid post-surgery recovery, less blood loss, and a faster return to sports and general activities than for fusion.

Vertebral Body Tethering

Vertebral body tethering (VBT) also known as anterior scoliosis correction (ASC) or the Tether, is performed anteriorly (through the side) using small incisions called portals with a scope and camera placed for visualization and access to the spine. These small incisions result in minimal scarring that is well hidden under the arm.

The muscles of the side are not cut but carefully separated, making recovery faster and allowing strength and function to return more quickly than with a spinal fusion. Through the portals, the surgeon places screws in the spine bones (the vertebra) and applies a flexible tether. The idea is that the tension on the tether pulls the spine back into its proper alignment, eliminating the scoliosis curve.

Tether is a non fusion scoliosis surgeryThe Tether device applies tension to the spine resulting in correction of the curvature.

In growing patients for whom the procedure is currently indicated, the approach takes advantage of future growth to further correct the scoliosis over time. Possible complications associated with VBT include cord breakage and overcorrection and the potential for further operations. However, with careful patient selection, these problems have not resulted in high re-operation rates and corrections have been excellent overall.

Younger patients with abundant remaining growth and patients with larger and stiffer curves are more likely to have overcorrection or incomplete correction of the curvature(s), respectively. The best indications and time to perform surgery are still being studied. For patients with less remaining growth, two cords are often used to decrease the likelihood of cord breakage. As for any new procedure, long-term outcomes cannot be known, but VBT leaves all options on the table.

For example, if the cord breaks, most patients do not lose enough correction to require a revision surgery. But if you do lose some of your correction, you can have the cord replaced. In time, cords will be engineered that are stronger and longer lasting. Fusion also remains an option after tether surgery but once performed, a fusion cannot be undone. 

So, there is a trade-off that families must consider in choosing a non-fusion approach: flexibility and some uncertainty in the outcome versus a spinal fusion which eliminates motion but is likely to be a long-lasting solution. Early (two- to four-year) results in the medical literature report a clinical success rate up to 74% and researchers are are currently studying preservation of motion in the tethered portions of the spine.2

10-year-old who underwent vertebral body tetheringA 10-year-old girl who underwent VBT and is doing well at 3 years post-surgery.

Is VBT Right for You?

For some patients with large curves, VBT is not indicated due to the severity of the curvature. A large curve that is stiff cannot be adequately corrected with a tether. There are techniques that can make a larger, and stiffer curve more flexible and correctible such as disc release but the long-term outcomes of this have yet to be reported.

In some patients, the thoracic (mid-back) curvature is very large but there is a smaller lumbar (lower back) curvature that is amenable to VBT. In those cases, we offer a hybrid fusion of the thoracic curvature where loss of mobility is less noticed by the patient and a VBT is performed for the lumbar curvature where flexibility is so important and where a fusion extended into the lumbar spine results in disc degeneration.

Hybrid fusion A 14-year-old girl who underwent a hybrid fusion of the thoracic curvature and VBT of the lumbar curvature and is doing well at 1 year post-surgery

ApiFix

The other non-fusion option for scoliosis surgery is ApiFix. Posterior dynamic correction is performed posteriorly (from the back), using an internal bracing system, ApiFix. The device is secured to the spine with a single level fusion at the top using two screws and a single screw at the bottom of the device. It acts as an internal brace for the spine and corrects the curvature without a long fusion of the spine. The recovery is the quickest of all available procedures. Correction is achieved at the time of surgery and your spine specialist can further dial in the correction over time through a ratchet system.

ApiFix deviceApiFix device, which serves as an internal bracing system to correct the curvature of the spine.

Possible complications include device loosening or breakage and re-operation. 3-4 The procedure may be best reserved for patients who have failed a brace or cannot tolerate a brace.

ApiFix caseA 12-year-old girl who underwent posterior dynamic correction after being intolerant to bracing.

While there is some overlap in the indications for VBT and ApiFix, surgeons can assist families and patients in making the right choice depending on the patient’s activity level, curvature size, and goals for treatment (see Table below).

Scoliosis surgery optionsFamiliarize yourself with the pros and cons of each type of scoliosis surgery

Updated on: 07/20/21
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