FDA Misses Deadline to Require Testing On Metal-on-Metal Hip Implants

Federal regulators are dragging their feet on industry requirements that could prevent dangerous and defective metal-on-metal hip replacement systems from getting to the market, according to an editorial in a leading medical journal. 

The editorial, published on January 10 in the New England Journal of Medicine (NEJM), notes that the FDA missed a deadline last month that would have removed the ability of medical device manufacturers to introduce new metal-on-metal hip implants onto the market without clinical trials on safety and effectiveness.

The editorial also notes that it is unclear when the FDA will actually make good on its commitment to more effectively protect the public from harmful and poorly designed medical devices.

Recalled Metal Hips Never Needed Clinical Trials for Approval

At issue is the FDA’s 510(k) fast-track approval process. Under this process, some medical devices are allowed onto the market without testing if they can be shown to be “substantially equivalent” to a device already in use.

Most metal-on-metal hip replacement systems have gotten to the market this way, meaning virtually none were tested thoroughly before they were implanted in patients commercially. A number of the designs have since been recalled, and many doctors and health experts say that the entire metal-on-metal hip implant concept may be flawed and defective.

In the case of one recalled metal hip implant, the DePuy ASR XL Acetabular Cup System, the implant’s 510(k) application actually used three different, previously approved devices to claim it was substantially equivalent, the editorial notes. Each device had a different feature that was included in the ASR, but none had ever used all three features together, meaning that DePuy was able to get what was essentially an entirely new medical device onto the market and into patients’ bodies without any testing required.

Metal artificial hips fall into the Class III category of medical devices, which includes high-risk medical devices and those awaiting proper classification. All Class III devices are supposed to undergo rigorous premarket approval (PMA) processes, as opposed to the 510(k) program. However, they were given temporary reprieve from that law, laid down in the 1976 Medical Device Amendments, until the FDA classified them or made concrete regulations for PMA. Once Congress saw that the FDA was not doing that, it ordered the agency in 1990 to create a schedule to transition to PMAs for all Class III devices.

That deadline passed on December 31, 2012, and the FDA has yet to comply and complete the congressionally-mandated transition to PMA. This means that manufacturers can continue to get metal-on-metal hip implants approved by the FDA without ever having tested them to see if they actually work or if they are dangerous to patients.

Thousands Need Revision Surgery Due to Failed Metal Hip Implants

Critics say this has led to a number of high-profile metal-on-metal hip recalls, as well as thousands of patients who have had to undergo revision surgery because their implants failed, possibly because they were never actually tested before being sold. The most high profile of these recalls occurred in August 2010, when Johnson & Johnson issued a DePuy ASR metal-on-metal hip implant recall that affected 93,000 units sold worldwide, and about 11,000 sold here in the U.S. The recall came after the manufacturer, Johnson & Johnson subsidiary DePuy Orthopaedics, determined that the devices had a failure rate as high as 13%. Some independent estimates say the failure rate is closer to 30%.

The problem appears to be in the metal-on-metal ball and cup design. The metal parts, made of cobalt and chromium, rub against each other, shedding metal debris into the surrounding tissue. This can lead to inflammations and a form of metal blood poisoning known as metallosis. It can also cause the devices to fail prematurely.

Johnson & Johnson now faces thousands of DePuy ASR hip lawsuits. All lawsuits over the implant filed in U.S. District Courts throughout the country have been consolidated for pretrial proceedings as part of an MDL, or multidistrict litigation. The proceedings have been centralized before U.S. District Judge David Katz in the Northern District of Ohio.

Nearly identical claims have been filed against the DePuy Pinnacle hip implant. Manufacturers of other metal-on-metal hip systems also face similar lawsuits over problems with their implants, including the Biomet M2A-Magnum hip and Wright Medical Conserve Plus hip. 

“As thousands of Americans are painfully learning, there are unknown risks with devices that enter the market without clinical data showing safety and effectiveness,” the NEJM editorial states, “and implanted body parts cannot be recalled as easily as defective auto parts.”