Friday, January 18, 2013

510(k) Ancestry Reveals Serious Flaws of Metal-on-Metal Hip Implants

Public Health Watchdog

Overview: A new report in the New England Journal of Medicine (NEJM) focuses on the 510(k) ancestry of the DePuy ASR XL hip system, highlighting issues common not only to that device, but to the metal-on-metal hip industry as a whole. The 510(k) route is a process that allows new devices onto the market without any clinical testing for safety or efficacy. Although initially meant for low risk products, 510(k) has been and continues to be a route that approves high-risk devices such as metal-on-metal hip implants.
  • An NEJM article discusses 510(k), a route used to approve devices without testing for safety or efficacy as long as the manufacturer can argue that it is substantially equivalent to a previously approved device
  • The articles focuses on the DePuy ASR XL, which was recalled in 2010 due to a high rate of revision
  • According to the NEJM article, the DePuy ASR was approved through 510(k); the devices cited as predicates differed substantially in design from the ASR and some showed poor clinical performance
Johnson & Johnson/ DePuy OrthopaedicsBiometSmith & NephewZimmerWright Medical Technology
ASR (recalled)M2a MagnumOxiniumDuromCONSERVE Hip Systems
Pinnacle Birmingham BHR Profemur

Side Effects & Complications
  • High failure rate
  • Necrosis (tissue death)
  • Increased levels of cobalt and chromium ions
  • Pain at the implant, sometimes spreading to the groin and back
  • Osteolysis (bone loss)
  • Fluid collections/solid masses around the hip joint

510(k) Approves Devices without Safety Tests
The NEJM perspective piece, published last Thursday, discusses the 510(k) process and the approval of metal-on-metal hip implants, specifically the DePuy ASR. The 510(k) will allow a device on to the market without clinical testing for efficacy or safety if the manufacturer can prove that is it “substantially equivalent” to a previously approved device, even if that product was never tested or showed poor clinical performance. The report points out that this approval route was only meant for low and moderate-risk devices, such as tooth brushes and infusion pumps, respectively. High-risk devices, also deemed as Class III devices under the Medical Device Amendments of 1976, were meant to undergo the stricter premarket approval (PMA) process, which would mandate clinical testing. However, the Class III devices were allowed to go through 510(k) temporarily until the U.S. Food and Drug Administration (FDA) down-classified the devices or implemented regulations requiring premarket approval. According to the report, “Congress had always intended class III devices to undergo PMA, and in 1990, it directed the agency to establish a schedule to finish the transition to PMAs for all devices that were to remain in class III.” Even though the FDA said it intended to complete this by December 31, 2012, by December 10th, 2012 the agency has still not completed the transition.

DePuy ASR XL Approved Through 510(k)
The DePuy ASR XL hip system, which was recalled in 2010 after data from the National Joint Registry of England and Wales indicated a revision rate of 13 percent in five years, was also approved through 510(k). The authors of the report used documents from the FDA database and the Freedom of Information Office to trace the ancestry of the ASR XL over the past fifty years. According to the report, the 510(k) approval of the recalled device focused on three specific characteristics: the porous bone ingrowth surface, metal-on-metal articulation and large femoral head sizes. These three aspects were combined for the first time in the ASR XL; none of the “predicate” devices cited in the approval combined all these features together. Furthermore, many of the devices used to prove substantial equivalence differed substantially from the ASR XL while others demonstrated poor clinical performance.

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