The FDA has recently approved the first spinal tether device intended for use by children and adolescents with idiopathic scoliosis. This device, the Tether – Vertebral Body Tethering System is intended to treat those who did not have success using conservative treatments like external bracing. These candidates for the Tether System display spinal curves that require or are close to requiring surgical treatment.
“For children and adolescent patients with idiopathic scoliosis that does not respond favorably to bracing, treatment options have been limited to fusion surgeries,” explained Capt. Raquel Peat, Ph.D., director of the Office of Orthopedic Devices in the FDA’s Center for Devices and Radiological Health. “Today’s approval provides access to a new treatment option that could improve quality of life for patients with idiopathic scoliosis.”
What is Idiopathic Scoliosis?
Idiopathic scoliosis, the most common form of scoliosis, is characterized by lateral curvature in the spine with no known cause. This is the most common spinal deformity in children and is seen most frequently in patients between 10 and 18 years of age but can be seen in patients outside of this age range as well.
Traditional treatment options for adolescents and children with idiopathic scoliosis who are still growing are non-surgical, such as external bracing to correct the spine’s curvature. Nearly 7,000 U.S. patients a year develop spinal curvatures that do not respond to these conservative brace treatments.
For these patients, the next option is spinal fusion surgery, an operation in which implants are placed in the spine to correct this curvature. This procedure has success in correcting idiopathic scoliosis, however, it permanently limits the patient’s range of motion. In addition, long-term complications such as pain, spinal deformities, and arthritis accompany this surgery in some circumstances, requiring further operation.
The Tether – Vertebral Body Tethering System
The Tether System provides idiopathic scoliosis patients who do not respond to external braces with an alternative to spinal surgery. This device is designed to continue correcting the spinal curvature as the patient grows. Compared to spinal fusion surgery, the Tether System grants the patient a greater range of motion.
The device consists of anchors and vertebral screws that are placed on the same side of each vertebra in the location of the spinal curve. These components are implanted through an incision made on the side of the chest. Each screw is connected to the tether, a flexible cord that applies tension during surgery to correct the spine’s curvature using compression.
The tether slows the growth of the curved side over time and promotes growth on the opposite side, providing spinal correction throughout the patient’s growth and development. The device is not to be removed unless an issue such as overcorrection arises. The physician will follow up on the patient’s progress via x-rays to track the spine’s curve and identify potential issues that may require revision. If the patient’s scoliosis does not improve with the Tether System, spinal fusion surgery is still an option.
FDA Approval of the Device
The FDA reviewed data regarding the Tether System using the humanitarian device exemption process, which is designated for devices that are designed to treat or diagnose conditions that affect less than 8,000 U.S. patients a year.
The study that the FDA analyzed included 57 patients who received the device. Two years after the operation, 43 of these patients displayed improvements in their spinal curvatures and did not need spinal fusion surgery. The most common adverse outcomes associated with the procedure were overcorrection, broken tether, and pneumothorax (air leaking into space between the lung and chest wall). Zimmer Biomet Spine, the company that received FDA approval for the device, will be partnering with the Harms Study group to create a patient databank that will analyze the long-term performance of the Tether System.
“The FDA continues to collaborate with stakeholders to encourage the development of registries, including the one being developed for this device, as an additional tool to gather and track real world evidence,” said Amy Abernethy, M.D., Ph.D., and FDA Principal Deputy Commissioner. “This type of post-market data generation can provide ongoing device safety surveillance and additional evidence for effectiveness. More broadly, real world evidence can help support innovative developments while ensuring that patient health and safety remains the top priority.”
— Medscape (@Medscape) August 22, 2019