DePuy ASR Total Hip Replacement
The Device
Designed by Johnson and Johnson’s subsidiary, the ASR total hip replacement device was released in 2005 after obtaining 510k clearances from the FDA. Such clearance allowed the manufacturer to enter the market without first evaluating the safety and effectiveness of the device on the basis of ‘substantial similarity’ to previously cleared devices.
The purported advantage of the device was two-fold. First, the device used a chromium-cobalt alloy, hypothesized to reduce wear damage and consequently last longer. Second, instead of using traditional adhesive cement, or screws to bind the device to the skeleton, the ASR is covered in a porous metal coating, facilitating natural adhesion via bone growth into the pores. Since its release, 93,000 devices have been installed worldwide.
The Controversy
Since 2005, the ASR device has suffered multiple blows from academic, medical, and government reports; ultimately resulting in DePuy recalling the device in July of 2010[1]. The magnitude of such a catastrophic failure is strongly evidenced by Johnson and Johnson’s most recent financial statement indicating the company had set aside $992 million dollars in anticipation of litigation[2]. These funds will be used to litigate, and settle, claims arising from both the defective nature of the device, as well as potential heavy metal poisoning.
Evidence of the substandard nature of the ASR device began to surface in 2008, with reports by both the FDA and the British HMRA (the British equivalent to the FDA). In their report, the MHRA detailed evidence of ‘genetic damage in patients with certain metal hip implants,’ including those with the same components as the ASR. In addition, the report cites the potential for systemic immunotoxic effects, local immune effects, and increased levels of metal in serum [3]. In the same year, the FDA reported over 400 complaints from or about patients with the ASR device. Thirteen percent of patients with the ASR device required a second surgery to replace the defective device[4].
A year later, the Australian Joint Registry investigated metal on metal bearings, concluding that both the Zimmer Durom, and the DePuy ASR exhibited higher than average revision rates. Specifically, the authors pointed out that 41% of the devices exhibited loosening, while noting a pattern of extensive wear markings, corrosion, and some carbide precipitation (which can affect wear and mechanical performance)[5].
Subsequent reports support the conclusion that the ASR is an inferior device. Difficulty installing the device, as well as getting it to adhere to the body, have resulted in unreported data from the UK and Wales Joint registry, suggesting a failure rate requiring revision between 11-13%[6]. There have also been subsequent studies pointing to the danger of having heavy metal particles, which enter the bloodstream after separating from the device during movement, accumulating in the body. Specifically, clinical research has shown that a small percentage of patients with a metal-on-metal device similar to the ASR exhibited adverse reactions to metal debris, requiring revision. These patients further exhibited higher blood levels of Cr and Co ions than asymptomatic patients[7]. Genotoxicity, which can alter the structure or integrity of genetic material in an organism, has also been reported by the British Committee on the Safety of Devices[8]. The danger of this form of toxicity is that it can result in cancer, or if the damage occurs in reproductive cells, inherited disorders in offspring. Finally, as these metal ions are excreted through the kidneys, internal damage can be exacerbated in those with renal failure, or those at risk of renal failure.
Symptoms
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Unexplained hip pain
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Difficulty standing or walking
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Loss of mobility
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Intense lift-off pain, noted as the most common symptom
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Behavioral effects associated with heavy metal poisoning
If you or a loved one have a DePuy hip implant, please contact Freese & Goss today.
[1] DePuy ASR Hip System Recall Guide
[2] Johnson and Johnson Reports 2010 Fourth-Quarter and Full-Year Results, January 25, 2011.
[4] Natasha Singer, Johnson and Johnson Recalls Hip Implants, NY Times, August 26, 2010.
[5] Metal-on-Metal Bearings: How Effective? Royal Perth Hospital, Bioengineering Bulletin, March, 2010.
[6] DePuy ASR Hip System Recall Guide.