A History of DePuy ASR Hips
On August 26, 2010, Johnson and Johnson subsidiary DePuy Orthopaedics, a division of Johnson & Johnson, issued a voluntary recall of the DePuy ASR™ XL Acetabular System and DePuy ASR™ Hip Resurfacing System.
It has never been a smooth ride for DePuy with the ASR, yet somehow, some 93,000 devices were installed worldwide since 2003. The ASR Recall has cast a harsh light on the power manufacturers have to push devices onto the market and keep them there.
Recalling a medical device is obviously not like recalling some part of a car or typical retail product. Patients are now being faced with the very real possibility that the hip they believed would support them longer than its competitors is not only failing prematurely, but has, in fact, caused irreperable damage.
A Questionable Beginning
In 2005 the FDA approved DePuy's ASR™ XL Acetabular System: a total hip replacement device. The approval from the FDA, known as a 501(k) approval, is not the type of approval most consumers are familar with. From The New York Times:
Unlike new drugs, many of which go through a series of clinical trials before receiving approval from the Food and Drug Administration, critical implants can be sold without such testing if a device, like an artificial hip, resembles an implant already approved and used on patients.
That way, manufacturers can rapidly make small changes to a device to improve it. But those simpler procedures have also effectively created a loophole, experts say, that lets producers bundle a component from an unapproved implant into an existing design and sell a device with minimal testing. With the A.S.R., that process unfolded with devastating results. (Meier)
An ASR XL Acetabular System which is a total replacement shown on the left. Compare with the ASR Hip Resurfacing System on the right.
The FDA approved ASR™ XL Acetabular System was a total hip replacement; this means that not only is the joint (ball and socket) replaced, but the "neck" of the femur (or femoral neck) is also replaced. A rod coming off the artifical neck is inserted into the shaft of the femur.
DePuy wanted to get their ASR Hip Resurfacing device approved by the FDA as well, but no similar loophole was available, as resurfacing was a new technique in the US. Despite the fact that both devices share the same cup and ball design—the part that would prove flawed—FDA requirements only forced DePuy to submit their resurfacing device to clinical trials.
Problems arose during the clinical trials for the ASR resurfacing device; specifically, more fractures at the femur neck were occuring than should be expected. DePuy eventually withdrew their application for FDA approval, but continued selling the ASR resurfacing device in other countries.
Although it was never approved by the FDA, US doctors could choose to implant the ASR resurfacing device in what is considered an "off label" use. How much this may have been done is unknown; unlike other countries, such as the UK and Australia, the US does not have a national reporting database. Nor does DePuy, or any other orthopedic producer, track such implants.
This was also part of the reason many US doctors remained unaware of issues arising with the FDA-approved ASR hip. Although complaints can be filed with the FDA when a product fails, neither patients nor doctors are required to submit them. Many U.S. doctors and hospitals do not bother filing complaints with the FDA in the event of products failure. As a result, product complaints are generally considered underreported; despite a lack of mandatory reporting, there were still more than 300 complaints filed with the FDA between January 2008 and March 2010 on the ASR.
In the absence of clinical trials and tracking data, many surgeons chose a device based on marketing or financial incentives. In 2007, DePuy was among four device makers who settled with the US government over an investigation into kickbacks being paid to doctors. In order to avoid criminal prosecution, DePuy paid $84.7 million and agreed to reforms.
According to a Reuters article, U.S. Attorney Christopher Christie said of the probe into implant manufacturers: "Prior to our investigation, many orthopedic surgeons in this country made decisions predicated on how much money they could makechoosing which device to implant by going to the highest bidder."
However, even doctors who had once been persuaded to use the ASR were starting to doubt its design.
Doubts Emerge, DePuy Deflects
In 2007, British orthopedist Dr. Antoni Nargol began seeing patients complaining of pain at or near their new hip. When Dr. Nargol approached DePuy with concerns, he initially took to heart DePuy's argument that it was his surgical technique that was at fault; that he was improperly positioning the socket of the artificial hip.
Although Dr. Nargol had initially accepted DePuy's argument about improper positioning, he continued to see ASR patients with problems. In November 2007, Dr. Nargol presented some of his adverse findings at the Seventeenth Annual Fall Meeting of the American Association of Hip and Knee Surgeons. In addition to a "poor" performance rate for the ASR resurfacing device in women, he and his fellow researcher had "growing concerns regarding metal ion debris reactions and conclude[d] that the incidence of this immunological response to metal wear products is higher than previously thought." 1
"After I gave my talk," Dr. Nargol said, "surgeons were sort of lining up to say 'I've seen one of two of these in patients and we just didn't know what it was.' And that's when I realized that perhaps the problem was a bit bigger than we thought."
Around the same time Dr. Nargol was talking with DePuy officials and presenting his data in Dallas, the Australian National Joint Replacement Registry's 2007 annual report found that the DePuy ASR™ Hip Resurfacing System had at least double the risk of revision compared to others. By the following year's annual report, the DePuy ASR™ XL Acetabular System poor performance was also reported.
According to the British Medical Journal, the Australian joint registry warned DePuy 17 times between 2007 and 2009 about problems with the ASR, including a revision rate twice what was expected.9
Amid growing concern for their patients, Dr. Nargol's colleague, Dr. David Langton began to notice that many of these patients had elevated chromium and cobalt levels. In 2008, Dr. Langton presented his findings "describing problems caused by the shallowness of the cup [that] was leading to increased wear" (Cohen, 2011). DePuy representatives were in attendance at this British Orthopaedic Assocation Conference, but still, nothing changed.
By January of 2009, Dr. Nargol and Dr. Langton and engineer Tom Joyce from Newcastle University completed additional studies which led them to conclude the design of the ASR's shallow cup was at the crux of the problems with the hip. DePuy officials maintained confidence in their product, arguing they had not been made aware of any similar issues. "I told them I was done," Dr. Nargol told the NYT.2
In late 2009, DePuy finally made a move, voluntarily pulling the ASR from the Australian market. However, DePuy cited decreased demand for the device as the primary motivation, not safety.
Early in 2010, DePuy announced worldwide phase out of the ASR systems, again, citing slowing sales. A few months later, DePuy followed up the phase out announcement with an alert letter addressed to doctors describing the Australian Joint Registry data showing higher-than-average failure rates.
The letter described the Australian Joint Registry's data indicating that the ASR's failure rate was higher than expected. DePuy continued to sell the hip, however. DePuy said in a statement made shortly after the alert was released that "this is new and important information surgeons who continue to use ASR should have to inform their clinical decision making."3
It is odd DePuy chose to highlight the Australian data in their warning letter to doctors since they were soon to forget it.
Finally, a Recall
August 26, 2010, DePuy issued a worldwide recall of both the ASR Hip Resurfacing System and the ASR XL Acetabular System.Their reasoning? "New, unpublished 2010 data from the National Joint Registry (NJR) of England and Wales" revealing revision rates more than double what is expected after five years in both ASR products. The press release continues:
Previous post-market surveillance data from a variety of sources – including national joint replacement registries, published literature, company sponsored clinical trials, internal complaints data and unpublished clinical research reports – had shown lower revision rates and that the ASR hip was performing in line with other devices in its class.
Dr. Stephen Graves, director of the joint registry in Australia disputes DePuy's assessment of the information available to them. "This is why regulators should not rely so heavily on manufacturer data." He told The Independent in September 2010, "It is a complete untruth that DePuy did not have reason to withdraw the ASR before now; we have been telling them since 2007, but they allowed it to be used on thousands of people."8
"When it is clear to the orthopedic community that a company has not been honest, that is a problem," Graves complained to the NYT in December, 2010.
While the numbers DePuy cited in their press release—12% failure rate for the total hip replacement and 13% for the resurfacing device—were more than double the typical rate, the news would eventually get much worse. In March of 2011, the British Hip Society and British Orthopaedic Association released a statement revealing even higher rates of failure.
Revision rates at four years were 21%, with the potential for numbers to reach 35% if implants that are currently known to be painful worsened to the point of needing replaced. After six years, almost half (49%) of implants had to be replaced.
It is not just hip pain and/or weakness however, that is indicative of a problem. A May 2010 case study of two Alaskan implant recipients also found elevated levels of cobalt and chromium were causing negative systemic effects. The metal of the hip implant had worn off the device and metal ions that entered the blood stream affected cardivascular, neurological, and other systems within the body. The two Alaskan patients complained of problems such as hearing loss, tinnitus, fuzzy memory, tremors, discoordination, and vertigo. Both reported their symptoms improved after revision surgery.
Patients who feel great and have clean x-rays may be actually be suffering from a "silent pathology" caused by the metal debris shed from the ASR. These metal particles can cause extensive damage to the soft tissues, muscles, blood supply, and bones around the implant.
Dr. Nargol was horrified by the damage he saw when opening up the hips of patients who were happy with the results of their ASR hips (from June 2011):
We found a horrendous amount of metal debris and the cups often have sort of been loosened by the metal and the metal gets behind the cup—the metal debris—and gets into the bone and goes deep into the pelvis and blown holes in the pelvis, we're almost at the bladder. It's just unbelievable and the unbelievable fact is that the patients have no pain.... [L]ast year, we felt it was the odd patient, but with the recall, we're seeing so many that it really now needs to be highlighted around the world.
Do you have an ASR hip?
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- Program for American Association of Hip and Knee Surgeons Seventeenth Annual Fall Meeting; November 2 – 4, 2007; Gaylord Texan Resort, Dallas, Texas <http://www.aahks.org/meetings/anmeet/pastanmeets/2007FinalProgram.pdf>
- Meier, Barry. "The Implants Loophole," The New York Times. December 16, 2010. <http://www.nytimes.com/2010/12/17/business/17hip.html>
- Meier, Barry. "With Warning, a Hip Device Is Withdrawn," The New York Times. March 9, 2010. <http://www.nytimes.com/2010/03/10/business/10device.html>
- Tower, Stephen S. "Cobalt Toxicity in Two Hip Replacement Patients." State of Alaska Epidemiology Bulletin. <http://docs.google.com/viewer?a=v&q=cache:EJ7JpaEeklIJ:www.epi.alaska.gov/bulletins/docs/b2010_14.pdf+alaska+cobalt+blood+levels&hl=en&gl=us&pid=bl&srcid=ADGEESj0Bxgdy-DpnsfW1SMYNHocGGS1w7AfxXjtIV_D3zy7yh6A74kvnmwfLuwMiTziChPa4HF1hcfSu75sR-hwXHDuqiMT96ADzK-Yn3lWZhvs3L5lL6ZECAqTrpAqXCGTeQg2lwQ9&sig=AHIEtbSxjXoo1VLycwTetB4yxMBG5hliEg> May 28, 2010.
- Swan, Norman. "Hip Replacement Device Withdrawn," The Health Report. ABC Radio. August 30, 2010. <http://www.abc.net.au/rn/healthreport/stories/2010/2995626.htm>
- Edith Honan. "Device makers to pay $311 mln to settle kickbacks probe," Reuters. September 27, 2007. <http://www.reuters.com/article/2007/09/27/us-medicaldevices-fraud-idUSN2735855720070927>
- Statement by the President of the British Orthopaedic Association and the British Hip Society Executive Committee: Large Diameter Metal on Metal Bearing Total Hip Replacements. British Hip Society & British Orthopaedic Association. March, 2011. (PDF)
- Lakhani, Nina. "Thousands of patients left in agony by faulty hip replacements," The Independent. September 12, 2010. <http://www.independent.co.uk/life-style/health-and-families/health-news/thousands-of-patients-left-in-agony-by-faulty-hip-replacements-2077180.html>
- Cohen, Deborah. "Out of Joint: The story of the ASR," British Medical Journal. http://www.bmj.com/content/342/bmj.d2905.full. May 14, 2011.
If the cup of the replacement hip is set into the pelvis at the wrong angle, the ball may press the inside of the cup unevenly, putting increased pressure on the edge of the cup. This is known as "edge-loading." This increased pressure can cause excessive wear, material may slough off the replacement hip, and the joint may loosen.
The sloughed off metal can damage surrounding tissues and once it enters the blood stream, potentially effect far-removed systems and organs within the body. The level of cobalt in the blood should be monitored closely in patients with ASR hips [learn more about the damage metal from replacement hips can cause].
These problems are especially true of smaller diameter ASRs, considered below 50mm in diameter, a size primarily implanted in women. Ironically, this is the exact group DePuy chose to target in an advertisement in the UK (where advertising laws allow medical device ads, unlike in the US) as late as February 2008.
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