The US Food and Drug Administration (FDA) has proposed a new rule that would classify all hip joint metal-on-metal semi-constrained prosthesis with either cemented or un-cemented acetabular components as class III medical devices requiring the submission of a premarket approval application (PMA) or a product development protocol (PDP) instead of a 510(k) premarket notification.
The devices have been plagued with controversy around the globe. The devices, which claimed to be similar enough to predicate devices made with non-metal parts, have since been associated with high revision rates and the generation of metal (often chromium) shavings that have damaged the tissue of some patients.
Globally, some regulators have advised patients against using the devices. In June 2012, a panel of experts convened by FDA indicated that they, too, would recommend against their use, saying the devices' risks now outweighed their benefits. The panel did not recommend removing the devices from the market, however.
FDA's proposed rule is primarily aimed at closing something critics have routinely derided as a "loophole." Medical devices are a relatively recent addition to FDA's regulatory authority, having only been authorized in 1976. Because some medical devices were already marketed at that time, FDA classified them all as class III, high-risk medical devices until it could review and classify them properly.
Some of those devices went on to serve as predicates for 510(k) premarket notification applications, which claimed that they were substantially equivalent to already-approved devices and were thus able to avoid conducting clinical trials to re-prove their safety and efficacy.
The problem with that, claim researchers, is that many of the original devices which metal-on-metal hips claimed to be ancestors of have since been recalled from the market under dubious circumstances, meaning the devices might never have been safe to begin with. Further, the metal-on-metal hips were not so similar to the original device as to be clearly substantially equivalent. Devices of this sort are routinely approved and are referred to as "split predicates."
In light of those concerns-and a lack of action on the part of Congress during the 2012 passage of the FDA Safety and Innovation Act to explicitly close the so-called loophole-FDA announced on 17 January 2013 that it would move to require all metal-on-metal implant devices to be submitted in the form of a PMA or PDP, which typically require clinical trials in support of the application and thus an investigational device exemption (IDE) application as well.
The new PMA requirements for metal-on-metal hips are scheduled to begin 90 days after the rule is finalized. Devices already on the market will be allowed to continue being marketed while FDA reviews their PMA or PDP submission, FDA said, so long as it is "timely filed" within 90 days of the date of issuance. After that time, the devices would be deemed "adulterated."
"FDA [also] recommends that IDE applications be submitted to FDA at least 30 days before the end of the 90-day period after the issuance of the final order to avoid interrupting any ongoing investigations," the agency said.
Comments on the proposed rule are due 90 days after the notice's final publication in the Federal Register, expected to occur on 18 January 2013.