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Artificial Hip Recall Shows Dangers of a Broken Medical Implant System

The A.S.R., or Aritcular Surface Replacement, artificial hip was promoted by Johnson and Johnson as a breakthrough in design that would last 15 years or more and provide patients with more natural movement. Now, the device has been recalled due to patients developing inexplicable pain and surgeons discovering mysterious masses of dead tissue in patients who are having the device replaced. DePuy Orthopedics, the Johnson and Johnson unit responsible for the hip and the largest maker of replacement hips worldwide, maintained that the hip was working for a long time despite warnings that it was a failure.

As pointed out in a recent New York Times article, the trouble with the hip is an indicator of a bigger problem: a piecemeal, broken medical implant system. Critical implants are sold without going through medical trials and testing or gaining FDA approval if the device resembles an implant that has already been approved. Theoretically, this allows manufacturers to make small changes to devices without having to jump through approval hoops; however, according to experts, it has also created a loophole that allows manufacturers to bundle an unapproved component into an existing design and sell it with minimal testing.

This is what happened with the A.S.R. as DePuy announced late last year that it was phasing the device out. However, the company blamed lagging sales rather than safety issues. In a recent statement an official stated that, “We believe we made the appropriate decision to recall at the appropriate time given the available information.”
DePuy does not know how many patients received the faulty device but estimated that about one third of 93,000 patients worldwide who received the implant were in the United States. This lack of exact numbers or documentation brings up another problem: the lack of an independent monitoring system in this country to track implant failures. If the U.S. had a database like those used elsewhere, doctors may have been clued into the problem a lot sooner.

Some doctors did try to get the word out about the problem but were rebuffed by DePuy. In fact, according to the director of Austrailia’s orthopedic database, data showed that the A.S.R. was failing earlier and at a higher rate than other devices all the way back in 2008.

Patients who have a defective A.S.R. require additional painful surgery to replace the device. Worse yet, some are permanently disabled due to damage to their bone, muscles, and nerves. Suffering patients often do not even know that the hip component that caused their disability is part of another device the FDA never approved.

DePuy initially developed the A.S.R as a “resurfacing implant,” composed of a cup and thigh component, used in a procedure where less of a patient’s thigh bone is removed compared to a standard hip replacement. However, because the resurfacing was a new procedure, the FDA required that implant be tested in a clinical trial before it could be sold in the US. So, in 2005, the FDA allowed DePuy to sell another version of the same device, a modified standard hip replacement containing the same cup found in the resurfacing device, thus, getting around the clinical trial requirement. Current rules do not even require producers to notify the FDA when they bundle components from approved and unapproved devices.

According to British doctor Antoni Nargol, in 2007 his A.S.R. patients started complaining of groin pain. Nargol claims he told DePuy officials that he found an explanation for why the device was failing. However, the company did not stop selling it, or even issue a warning. Instead, the company blamed the failures on the doctor’s surgical technique. At first, Dr. Nargol thought surgical technique could have been the problem. However, another orthopedic resident, Dr. Langton was not so sure so he began taking blood samples of patients using the A.S.R. and a competing device who were not experiencing pain. The tests showed elevated levels of cobalt and chromium in A.S.R. patients (used in the device) and soon proved that placement error was not the problem. As doctors in Britain and other countries operated on patients to remove the device, they found metallic debris shed by the device was causing a chemical reaction that destroyed muscle and bone. By early 2009, more testing revealed that the cup that the FDA had allowed to be sold without testing was the heart of the problem due to an interior surface that was too shallow.

This case is not the first time that problems with orthopedic implants emerged in registries outside the U.S. well before doctors here stopped using defective devices. Device companies, rather than doctors, patients, or regulators determine when safety alerts are issued or products are withdrawn from the market. DePuy actually did issue a safety alert about the A.S.R., a year after data revealed it was dangerous, and even then it was still on the market.

This episode has led to a wave of litigation around the world. In addition, officials have renewed there efforts to begin an orthopedic registry in the US. Many believe that such a system will only be effective if the federal government mandates reporting of data as a condition of payment of taxpayer funded programs like Medicare. The FDA has recently proposed rules that could require implanted devices to undergo more thorough testing before they are approved for sale, however, the fate of the proposals is unclear and receiving opposition from the device industry.

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