Metal-on-Metal Hips: A Tale of Harm, Weak
Medical Device-Approval, and Lax Postmarket Scrutiny

Hip replacement, National Institutes of Health

Nearly 1 million metal-on- metal hips have been implanted in patients in the United States, making the US the world’s largest consumer of the implants. According to a BMJ/BBC Newsnight Investigation released today, the “risks associated with these devices have been known for decades, yet patients have been kept in the dark about their participation in what has effectively been a large uncontrolled experiment.” At issue are “leaky hips,” specifically, “release of metal ions that can seep into local tissue causing reactions that destroy muscle and bone and leaving some patients with long term disability,” writes Deborah Cohen, BMJ’s Investigations Editor. In a companion paper, Carl Heneghan, MD, director of the Centre for Evidence-Based Medicine, University of Oxford, Oxford, UK, and coauthors, point to the litany of safety warnings out on these implants for a decade or more.

Together, these reports point out:

• internal memos deemed proprietary acknowledging safety issues dating back more than a decade;
• lack of medium-to-long-term safety and reliability data on these devices;
• uncertainty about safe levels of metal (cobalt and chromium) ion exposure;
• design flaws;
• a weak device regulatory approval process, seemingly more intent on rapid market entry, and not requiring clinical data submission prior to approval;
• postmarketing databanks in the EU that alone are insufficient for flagging safety;
• and despite all of this, exhibitors at a February 2012 American Academy of Orthopedic Surgery annual meeting, showcased metal-on-metal hips to thousands of attendees.

This story is hardly new, but what’s alarming is that the metal-on-metal hip story is emblematic of how thousands of medical devices like hip implants get out to market. FDA does not require clinical data submissions, but merely proof that the implants are “substantially similar” to other devices already out there through FDA’s 510(k) program.

Richard Deyo, MD, Professor of Evidence-Based Family Medicine, Oregon Health and Science University, Portland, OR, reviewed the report. In an email, Deyo wrote: “I think implanted medical devices should have much closer pre-approval scrutiny than they currently receive, and there is a need for much better post-marketing surveillance. The latter might uncover problems of this sort before too many patients are affected.”

As far as patients are concerned, Deyo wrote: “Patients may want to inquire as to the length of the track record for any implantable device. This is a situation where it’s not safe to assume that the latest is the greatest. It often takes years to learn about the durability of implants, and some new devices prove to be worse than older ones.”

Rita F. Redberg, MD, Professor of Medicine at the University of California San Francisco, told Patient POV:  ““We are dependent on foreign registries for data on hip implants and currently,there is no provision that would require collection and reporting of such data.” Redberg says we need more data in the  FDA premarket process, as well as more consistent and complete postmarketing surveillance. “A  US hip and knee registry would help,” Redberg said, adding that plans for such are moving very slowly.

Hip and knee replacement registries are further along outside of the United States. In 1999, Australia launched a mandatory, confidential hip and knee registry that generates detailed information on outcomes, implant performance, patient deaths, and revisions. Proponents say that it has been helpful in real-time quality control, in weeding out poorly performing implants, as well as pushing orthopods with less-than-optimal outcomes to improve their technique or stop doing implants. New Zealand similarly launched its registry in 1999.

In both Australia and New Zealand, individual surgeon data has not been discoverable, but this has been a sticking point for the US-based Association of Health Care Journalists and ProPublica, who have been fighting in the US to have the HHS National Practitioner Databank accessible at the provider level.

Patients need to think through who they should lobby to improve their odds of getting a safe, new hip, pacemaker, or new knee, should they need them. Thousands of devices become FDA approved through the 510(k) process, without clinical data submission. Sadly, I doubt most of us, including me, have tools available to make the best choice on where to go for a hip implant with a good track record and an orthopod with good outcomes. I haven’t found the websites of orthopedists very helpful.

A mandatory, real-time patient registry with uniform requirements would be a step in the right direction, but headway in this area has been slow. Putting safety first and insisting that industry submit clinical data before the FDA approves new devices is paramount. The 510(k) process needs to be abandoned and supplanted with clinical data reviewed by FDA. Postmarketing surveillance needs to be ramped up so that safety problems are flagged as early as possible. Comparative effectiveness research could also go a long way in evaluating the safety of implanted devices. Even though cost effectiveness research provisions are in place through the Accountable Care Act, orthopods have yet to contribute to the process.

An earlier version of this article misquoted Dr. Redberg. The corrected quote appears above.