Caring for adolescents with idiopathic scoliosis is a field ripe for development. In advanced cases, surgeons have few surgical options: fusions or complex procedures with growing systems.
Now, however, a few surgeons around the world are working on fusionless techniques that will allow young patients to continue growing without the challenges presented by growing rods.
"For most kids with scoliosis and spine problems, we have to perform a fusion on them," says Amer Samdani, MD, chief of surgery at Shriners Hospital for Children—Philadelphia. "Those procedures work well, but have their limitations — stunting growth and limiting activities. There is also long term sequela that may lead to additional procedures. We've been working on anterior vertebral body tethering which uses the child's growth to help modulate their scoliosis and gain correction."
Dr. Samdani and his colleagues have modified the Dynesys Dynamic Stabilization System (Zimmer Spine). This system is cleared for posterior lumbar surgery, and they are utilizing it off label for fusion less anterior thoracic surgery. "We've had very good success with controlling spinal deformity and avoiding a need for fusion in the right patients," says Patrick Cahill, MD, a spine surgeon at Shriners Hospital for Children—Philadelphia. "We are working on which patient populations can benefit from these techniques."
Dr. Samdani and his colleagues have done more than 70 of these procedures and seen positive results after two years. More than 90 percent of the patients studied have avoided a fusion, to date although longer term follow up is needed. Their data has been presented at a few professional conferences. Additional studies comparing it to traditional treatments such as bracing and fusion are needed.
"This procedure is not for every child, but if you select the right patient it's a real benefit because you prevent the convex side of scoliosis from growing so the concave side catches up and the child experiences correction without fusion," Dr. Samdani says. "The best patient is someone who is skeletally immature with a curve somewhere between 40 and 60 degrees."
Surprisingly, through his studies Dr. Samdani has found tethering can even have a positive impact on patients with up to 60 degree curves if the patient has enough growth potential. To perform the procedure, surgeons insert the tether thorascopically through three small incisions and run the tether through the screw heads. If necessary, the tether can be adjusted for growth and loosened to prevent over correction.
"There are only a few centers around the world doing this, although we expect that number to increase," says Dr. Samdani. "Some centers advocate removing the tether when the child is done growing; our policy is to leave it in if the child is doing well. However, I see a day when we would remove the tether after the job is done."
As technology for surgical AIS correction develops, work done at the Shriners Children's Hospital — Philadelphia will likely pave the way for even more advancement in the future.
"I believe the tether will be part of a potential solution for the growing spine, but there is a whole other cohort of patients that need the development of this technique," says Dr. Samdani. "In the future you'll see fewer fusions performed in the idiopathic area. As we get better with genetics — an area with a lot of active research — we'll be able to predict those patients at highest risk for progression. I see a day when genetic markers and fusionless interventions such as tethers will allow us to intervene earlier in patients, but that's still several years away."
While this technique research and development is in the early stages, there is still room for scoliosis treatment development in the short and long term.
"I think in the short term, we may be able to see a marriage between robotic surgery and navigation such that we will have surgeons develop a preoperative plan on a computer screen that can be carried out in an automated fashion without the surgeon placing the implant; I hope that will happen within the next decade or so," says Dr. Cahill. "In the long term, I would be excited to see pharmacological management of scoliosis as we are able to unlock and manipulate the molecular mechanisms of scoliosis and spinal deformity."
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