Metal On Metal Artificial Hips May Face More Scrutiny From FDA

It has been well-documented that metal-on-metal artificial hips – implanted in hundreds of thousands of patients across the country – tend to fail sooner and require replacement more quickly than other artificial hip products. Because of these artificial hip failures, there have been a number of hip implant recalls including recalls by DePuy (a division of Johnson & Johnson), Zimmer, and Smith & Nephew.

Artificial hip systems with identified problems include:

• DePuy ASR XL Acetabular Hip System and ASR Hip Resurfacing System
• DePuy Pinnacle Hip Replacement System
• Stryker Rejuvenate and ABG II Modular Hip
• Biomet M2A – Magnum Hip
• Wright Pro Femur and Conserve Plus Hip

In addition to orthopedic failures requiring additional revision surgeries, metal-on-metal artificial hips may permit grinding of the metal particles, which are then released into the patients bloodstream causing metal toxicity. As the New York Times reported in 2011, the results are gruesome:

"As surgeons here sliced through tissue surrounding a failed artificial hip in a 53-year-old man, they discovered what looked like a biological dead zone. There were matted strands of tissue stained gray and black; a large strip of muscle near the hip no longer contracted."

The Times cited a New England Journal of Medicine study that found that metal-on-metal artificial hips failed at 3 times the rate of other artificial hips. The problems have gotten so bad, the FDA ordered an in-depth study of metal-on-metal artificial hip systems. However, the FDA is leaving it up to each individual manufacturer how to conduct its study.

Remarkably, most medical devices recalled by the FDA in recent years because of deaths or life-threatening problems were approved under less stringent regulations that did not require human testing — meaning the devices were never tested in human patients before being implanted into hundreds of thousands of people.

Making matters worse, not only are these devices not properly tested, but the hip manufacturers pay doctors to actively promote the defective products. DePuy paid more than $80 million to doctors across the country to promote, research, and consult on DePuy's defective hips.

Section 513 of the Federal Food, Drug, and Cosmetic Act (the FD Act) (along with subsequent amendments) establishes 3 classes of medical devices intended for human use – Class I (general controls), Class II (special controls), and Class III (premarket approval , or PMA). These Class III PMA devices, as the name suggests, require human clinical testing and FDA approval before they can be marketed to the general public.

However, devices that were being commercially marketed before the adoption of the 1976 Amendments to the FD Act (“preamendment devices”) are exempted and have been allowed to be marketed without a PMA regardless of the Class designation. Taking it one step further, FDA’s 510(k) approval program allows any post-amendment device that was found “substantially similar” to a preamendment device to also be exempted from the requirement for human testing before being marketed. All that a manufacturer has to do is tell the FDA that a new device is similar to an existing device and they are allowed to market it with little or no testing.

It was under this 510(k) approval process that many, if not all, current metal-on-metal hip implants were brought to market. I have written extensively about the dangerous side effects these hip implants present. But despite the dangerous side effects, and the fact that manufacturers knew of the problems with the metal-on-metal design, the implants were allowed to be marketed and sold.

The FDA, this week, has proposed a new rule which would require premarket approval for two current Class III preamendments devices: the Cemented and Uncemented Metal-on-Metal Acetabular Hip Joint Prostheses. If finalized, this rule would close the loophole allowing these devices to be marketed without testing, and would all but ensure that these devices would be removed from the market. It is unlikely that manufacturers would submit to the costly PMA process in light of the known problems with these dangerous devices.

The text of the proposed rules is below:

§ 888.3320 Hip joint metal/metal semi-constrained, with a cemented acetabular component, prosthesis.

(c) Date PMA or notice of completion of PDP is required. A PMA or notice of completion of a PDP is required to be filed with the Food and Drug Administration on or before [A DATE WILL BE ADDED 90 DAYS AFTER DATE OF PUBLICATION OF A FUTURE FINAL ORDER IN THE Federal Register], for any hip joint metal/metal semi-constrained prosthesis with a cemented acetabular component that was in commercial distribution before May 28, 1976, or that has, on or before [A DATE WILL BE ADDED 90 DAYS AFTER DATE OF PUBLICATION OF A FUTURE FINAL ORDER IN THE Federal Register], been found to be substantially equivalent to any hip joint metal/metal semi-constrained prosthesis with a cemented acetabular component that was in commercial distribution before May 28, 1976. Any other hip joint metal/metal semi-constrained prosthesis with a cemented acetabular component shall have an approved PMA or declared completed PDP in effect before being placed in commercial distribution.

§ 888.3330 Hip joint metal/metal semi-constrained, with an uncemented acetabular component, prosthesis.

(c) Date PMA or notice of completion of PDP is required. A PMA or notice of completion of a PDP is required to be filed with the Food and Drug Administration on or before [A DATE WILL BE ADDED 90 DAYS AFTER DATE OF PUBLICATION OF A FUTURE FINAL ORDER IN THE Federal Register], for any hip joint metal/metal semi-constrained prosthesis with an uncemented acetabular component that was in commercial distribution before May 28, 1976, or that has, on or before [A DATE WILL BE ADDED 90 DAYS AFTER DATE OF PUBLICATION OF A FUTURE FINAL ORDER IN THE Federal Register], been found to be substantially equivalent to any hip joint metal/metal semi-constrained prosthesis with an uncemented acetabular component that was in commercial distribution before May 28, 1976. Any other hip joint metal/metal semi-constrained prosthesis with an uncemented acetabular component shall have an approved PMA or declared completed PDP in effect before being placed in commercial distribution.

[More on Defective Hips]

Read More:

• Metal Hip Implants Face Tighter Controls [Thomas J. Burton at The Wall Street Journal]
• Remedy Is Elusive as Metallic Hips Fail at a Fast Rate [Barry Meier at The New York Times]

© Copyright 2012 Brett A. Emison

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