The FDA has ordered the manufacturers of new, flexible pedicle screw spinal fusion implants, known as dynamic stabilization systems, to conduct more research on potential problems with the devices, including the whether they provide enough stability to allow for complete spinal fusion and the frequency of additional surgery for patients who receive the pedicle screws.
In a press release issued on October 5, the FDA expressed concerns that the spine surgery screws may lead to future complications for patients and indicated that they are requiring manufacturers to conduct post-market surveillance studies for existing systems, and premarket clinical trials for systems currently under development.
Pedicle screw systems are used during back surgery to stabilize the spine and allow the bones to fuse into the proper place. Older pedicle screw spinal implants were rigid and mostly inflexible, but the new dynamic stabilization systems are designed to allow the patient to experience much more flexibility during the fusion process.
Johnson & Johnson and Medtronic both have flexible pedicle screw systems on the market, while another system by Zimmer Holdings, Inc. is currently awaiting FDA approval.
To date, the devices have fallen under the FDA’s controversial 510(k) approval process, which expedites approval of devices that are similar in form and function to existing, approved medical devices without the need for an in-depth review. Critics of the process and a recent Government Accountability Office report claim that the 510(k) approval process has allowed a number of dangerous, unique and virtually untested products to slip past FDA regulators before being thoroughly vetted.
FDA regulators said that there is not enough clinical data on the potential safety issues, indicating that the system components may loosen, bend or break over time. If the pedicle screw fails to provide enough support for fusion or fails over time, this may require patients to undergo corrective surgeries that may lead to serious and even life-threatening complications.
Older pedicle screw system work by installing screws into segments of the spine and anchoring them to metallic rods. The rods immobilized the spine and allowed bones to fuse together. The new dynamic stabilization systems use polymer cords, movable screw heads and springs that allow the patient to bend and rotate while the bones are in the fusion process. The new systems began to appear on the market in 1997.
The FDA is requesting that companies provide data that compares the rate of bone fusion between the old and new devices, and data that compares the incident rates and severity of adverse events and the need for follow-up surgical procedures. The FDA also is looking for information on the causes of any known failures of the new systems, as well as data on the demographics of patients who experienced the failures.
The agency announced that once it has the necessary data, it will decide whether labeling changes or any further action is needed. Currently, the FDA is not recommending any changes.