Tethering Device Provides an Alternative to Fusion for Scoliosis Correction

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Eleven year old Baylee wanted to soar and tumble like Simone Biles. Or, at least, just like every other average kid. Her mother, Melissa, had reservations about Baylee having any procedure to correct her scoliosis that might impair her flexibility, like spinal fusion.  

At Shriners Hospitals for Children — Northern California, Baylee didn’t have to.

Pediatric orthopedic spine surgeon Rolando Roberto, M.D., performs a newly approved tethering procedure. It is less invasive than spinal fusion. It preserves mobility. And it has shown excellent results without the risk of some of the late problems associated with spinal fusion.

Over the past 10 years, the tethering device used for the spine has been a braided, polyethylene cord (a tether) instead of metal staples. Approved by the Food and Drug Administration in 2019, The Tether™ – Vertebral Body Tethering System (Zimmer Biomet Spine, Inc.), is attached to screws implanted in individual vertebrae on the convex side of the curvature, usually with the topmost screw at the T5 vertebrae and going as low as T12, sometimes into the lumbar spine. The screws are attached on the anterior part of the spine and the procedure is done arthroscopically. It requires that one of the lungs be deflated.

To date Dr. Roberto has completed more than 25 cases. The ideal candidate for tethering is a child who is going to need surgery, has a Cobb angle curvature between 50 degrees and 75 degrees and has two years of continued growth remaining.

According to Dr. Roberto, the cord has enough tension when the disks get compressed after the tether is attached to the screws. Consequently, there is some correction in the curvature immediately. But the main improvement comes as the child grows. 

The very first case of scoliosis tethering was in an eight-year-old patient with a 40 degree curve in his thoracic spine. A team from Washington University in St. Louis performed the procedure using a tether approved for use in the lumbar spine of adults (J Bone Joint Surg Am 2010;92:202-9). Four years later, in the published report on the case, the surgeons reported that the patient had overcorrected by about 11 degrees.

Dr. Roberto said that he recently learned that this boy still had a fair amount of growing to do after age 12. He ended up with a 50-degree overcorrection and opted to have a spinal fusion procedure.

After that first Louisville patient, much of the pioneering work was picked up by Shriners Hospitals for Children — Philadelphia, and its current chief of surgery, Dr. Amer Samdani. The tether uses patented methods and techniques developed by medical staff at the Philadelphia Shriners Hospital.

In fact, Dr. Samdani may have the most experience performing the procedure of anyone, having done more than 450 cases.

In a 2019 report that Dr. Samdani made at a meeting in Canada, on 53 patients with a mean follow-up of four years, he said that 86% of the patients now had a Cobb angle of less than 30 degrees, which is considered quite adequate, and the average Cobb angle achieved was 16 degrees. Only five patients needed surgical revision.

Dr. Roberto traveled to Shriners Hospitals for Children — Philadelphia to learn the procedure and later began performing them in Sacramento.

“The tethered kids do REALLY really well. They bounce back very quickly.” – Dr. Rolando Roberto

Baylee’s mother, Melissa, is a nurse. She learned about the tethering procedure. She and Baylee decided that was what they wanted Baylee to have, as her self-image was suffering and she was in pain. But, then they found that their insurance company was not going to pay for the procedure.

Shriners Hospitals for Children has no barriers to care, and accepts patients regardless of insurance coverage. So Melissa contacted the Philadelphia Shriners Hospital, and the hospital told her that she and Baylee did not have to travel so far. Baylee could have the procedure done less than 20 miles away  
in Sacramento.

Baylee is now a bit more than nine months out from her procedure. Six months into Baylee’s recovery, she was back to learning how to do back handsprings in her gymnastics class.

Dr. Roberto says that additional experience needs to be accrued, now that the tether is approved. He notes that tethers can break and some individuals get overcorrected. But, “the tethered kids do really, really well,” Dr. Roberto said. “They bounce back very quickly compared to fusion. And they are often able to do more [than with fusion].”

Like Baylee, Dr. Roberto’s very first patient is doing well too. He had a 65 degree curvature when he had his surgery, about four years ago. Now he has a 30-35 degree curve. Since then he is learning taekwondo. Moreover, recently he boldly informed his mother that he intends to play tackle football.

“She told me to tell him, ‘No.’” Dr. Roberto said. “But I don’t have that kind of control over teenagers. Neither does she.”

Asked if the prospect of America’s most physical sport for this patient worried him, Dr. Roberto said: “I think I’d be more worried about his head.” 

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