The Food & Drug Administration (FDA) is concerned about the safety of certain types of pedicle screw systems, called dynamic-stabilization systems, and has ordered the 16 companies that make and market these devices to conduct postmarketing safety studies.

Dynamic stabilization systems are used in spinal surgery and some are intended to provide stabilizing support to the spinal column during bone fusion.  Dynamic stabilization systems have different design features, polymer cords, moveable screw heads, and springs, that allow bending or rotation while still facilitating fusion. According to the FDA,  there is not enough clinical data to determine whether these dynamic stabilization systems provide enough spinal stability to allow for complete spinal fusion, as the system components may loosen, bend, or break over time. If fusion does not occur, a patient’s condition could worsen and possibly require additional surgical procedures.

The FDA cleared the first dynamic stabilization system component in 1997. The FDA is now requiring postmarket studies to address these potential risks for systems already on the market. The  postmarket surveillance studies must address the following:

• the fusion rate for dynamic stabilization systems compared to traditional stabilization systems;
• the incidence rate, severity, and time course of adverse events for dynamic stabilization systems compared to traditional stabilization systems;
• the type, incidence rate, and time course of subsequent surgical procedures for dynamic stabilization systems compared to traditional stabilization systems; and
• the cause of failure for dynamic stabilization systems based on analysis of all reasonable available systems that have been removed from patients, along with any association between the patient’s demographic and clinical data and the device failure.

In reviewing the clinical data gathered from the postmarket surveillance studies, the FDA will consider whether labeling changes or additional preclinical and clinical testing requirements are necessary for these devices.