Tags

, , , , , , , , , , , , ,


MoMs Hips a Grinding Dilemma for Hospitals, Doctors, FDA.

MoMs Hips a Grinding Dilemma for Hospitals, Doctors, FDA

Cheryl Clark, for HealthLeaders Media, July 5, 2012

As health providers focused on the Supreme Court’s ruling last week, a quieter but much more human drama about medical harm and suffering—and what federal policymakers should do about it—was unfolding inside a hotel just beyond the Maryland beltway.

For two days, a parade of orthopedic surgeons, biomedical device reps, safety experts, poison specialists, risk managers, lawyers, and patients appeared before a U.S. Food and Drug Administration panel to talk about the disastrous problems, questions, and fear surrounding MoMs.

MoMs, or metal-on-metal hip replacement or hip resurfacing systems, represent between 27% and 40% of the estimated 500,000 hip surgeries performed a year in the U.S., an industry valued at about $12 billion a year in 2009, although new procedures are apparently in decline.

Presumably, after this meeting, the FDA’s 18-member Orthopaedic and Rehabilitation Devices Panel is thinking about what to do to clarify the safety of these devices. Should they recommend suspension of all further MoM implants as many patients and physicians recommend? And how should they further inform fearful patients who as yet have no symptoms what they should do in the meantime?

During the two days, panel members heard a mind-boggling array of words and phrases to describe the damage to bone, tissue, and blood resulting from MoM devices:

Tribocorrosion, trunnions, fracture of resurfacing systems, edge wear, microseparation, pseudotumors and asceptic lymphocytic vasculiis-associated lesions, voltage effects, infections, post-operative nerve palsy, prosthesis loosening, implant breakage or fracture, femoral neck fractures and heterotopic ossification, loss of mobility and pain, and mechanically assisted corrosion, to name just a few.

Starting a decade ago, newer MoM devices were seen as a safer alternative to prostheses made of polyethylene or ceramic, which wore out faster, and which released particles that could accumulate in local tissue and erode the bone.

Metal devices, which would last longer, held a promise to solve that problem, because they were seen as more appropriate for younger people who wanted to remain active in their 60s and 70s and beyond without having to undergo a revision surgery.

But all hell broke lose four years ago when a raft of failure and toxicity issues surfaced among patients who had received two major MoM devices sold under the name DePuy, the ASR Acetabular System, and the ASR Hip Resurfacing System, both manufactured by Johnson & Johnson. In a statement announcing it was recalling these devices in 2010, DePuy officials acknowledged that 12% to 13% of patients required revision surgery after five years.

Class action lawsuits tumbled in.

Then more complaints and concerns came flooding in from many more patients, including many who received other MoM protheses made by five manufacturers.  Many patients, like Steve Lorenz of Whitehall, PA, said that when they told their doctors that they weren’t recovering from their hip surgeries, but were getting worse, they were brushed off.

“He disregarded every symptom, and then he equated what happened to him when he took a Pilates class with his wife,” recalls Lorenz’ wife, Pat, who testified before the FDA panel about the surgeon’s reaction to her husband’s complaints.

How did hundreds of thousands of potentially unsafe devices get into the market?

Many blame the fact that all of these MoM devices were approved by the FDA over the years under the 510(k) process. It presumes that a new device that is very similar to an approved device, does not need to undergo rigorous safety testing, since the device it is being compared to, has already passed those tests The 510(k) essentially gave such  devices a free ride.

In February, 2011, the FDA launched a MoM Hip Implant System website, which emphasizes some symptoms patients and their doctors should look out for, including ion toxicity in the blood from cadmium or cobalt particles resulting from metal contact with bone.

“At this time, it is not possible to know who will experience a reaction, what type of reaction they might have, when the reaction will occur, or how severe the reaction will be. However, it is known that over time, the metal particles around some implants can cause damage to bone and/or tissue surrounding the implant and joint,” the FDA website says.

David Langton, an orthopedic surgery resident at University Hospital in North Tees, Great Britain, has focused on MoM device research for the last four years and believes MoM devices of all types have been an “an absolute disaster,” with failure rates or required revisions in far more than 12%-13%.

His research discovered revision surgeries required in 49% of patients, many of whom experienced toxicity from excessively high levels of cobalt and cadmium in their blood.

“The 49% failure rate…we expect will be 80% in eight years, and there are three other [centers] in the UK which have quoted similar figures at meetings,” Langton wrote in an e-mail Wednesday.

Langton says he is “not so concerned about gross hip failures. I am very concerned about the theoretical risks that these blood levels may lead to.”

He adds that in the UK, which has the benefit of a hip surgery registry that the United States lacks, problems have shown up with the other devices too. “We do not believe this is a problem specific to DePuy,” he wrote. “I have seen similar failures with most of the other manufacturers’ hips, too,” he says.

In May 2011, the FDA issued 145 orders for post-market surveillance to 21 manufacturers of MoM total hip systems to develop a research protocol that addresses these complaints. Manufacturers, who are responsible for funding these studies, should track patients for eight years after surgery, conduct a failure analysis.

But in a New England Journal of Medicinearticle published Thursday, Joshua Rising, MD, Ian Reynolds and Art Sedrakyan, MD, of the Medical Device Initiative of the Pew Health group, lamented not only that these studies are taking a long time to start, they may never produce meaningful information.

Three weeks ago, “the FDA and manufacturers had reached agreements on study protocols for less than one quarter of the devices, most of the study plans had not been finalized, and it was unclear whether any studies had begun.  Moreover, methodologic issues will limit the usefulness of the information that emerges from these studies,” they wrote.

“One significant shortcoming (of FDA’s order) is that each manufacturer is permitted to conduct its own independent study on its product or products,” they wrote. “The resulting lack of harmonization among studies will lead to challenges in pooling data and making cross-product comparisons.”

Companies may measure chromium and cobalt levels differently and introduce “uncertainty into attempts to pool results.”

The authors advise the FDA to use “warning letters, fines, and removal from the marketplace to demonstrate its commitment to post-market surveillance.

“While the FDA and other stakeholders struggle with these systemic issues, the problems with metal-on-metal hip implants will continue to occupy the agency, clinicians, manufacturers, and thousands of affected patients for the foreseeable future.”

Some aren’t sure the problem is that extensive. Stephen Kantor, MD, an orthopedist with a high-volume hip surgery practice at Dartmouth-Hitchcock Medical Center in Lebanon, NH, doubts that the problems with MoM devices approaches that many patients. At his hospital, patients have normal blood work and feel fine.

And he wonders if some of the concern isn’t fear caused by the publicity over some bad DePuy cases.

But to be safe, he’s stopped putting MoM devices in his patients and thinks it’s reasonable for the FDA to put a temporary hold on their use until safety issues can be clarified. “I don’t know that they’re bad. But I don’t know for certain that they’re safe, and I don’t want to take that chance with my patients,” he says.

Cheryl Clark is a senior editor and California correspondent for HealthLeaders Media Online. 

Advertisements