NYT Challenges Metal-on-Metal Hips
BY LAUREN UZDIENSKI, MARCH 8, 2010
Wear debris and surgical technique are at the center of a New York Times article on metal-on-metal total hip components, with the paper suggesting that metal-on-metal correlates to poorer outcomes and higher revision rates.
Metal-on-metal components are used in about a third of the 250,000 hip replacement procedures in the U.S. each year, and the procedures utilizing these components are a mix of traditional THA and resurfacing cases. Wear debris, which is created when contact between the ball and cup sheds metal ions, may occur at higher rates with metal-on-metal components than metal-on-poly and ceramic-on-ceramic (another surface to which the Times has voiced its objection). This can lead to inflammation and tissue death and necessitate a revision as soon as one to two years after an initial procedure.
The article cites a metal-on-metal revision rate of 1-3%, with women affected more frequently than men. A surgeon at Rush University who was quoted by the Times says he revises metal-on-metal hips at a rate of about "one a month." The failure rate is largely attributed to surgeon technique, such as how implant components are aligned. This connection is not entirely new, particularly in terms of resurfacing; it has been well-documented that resurfacing is a complex procedure with a steep learning curve.
While the Times may be among the first to bring major media attention to metal-on-metal, questions about wear debris and device failure have been circulating in the scientific and clinical community for some time. Suggestions that the revision rate is higher for resurfacing than a conventional THA have been corroborated in a recent review by the AAOS, which noted that data from three joint registries showed an increased revision rate for resurfacing. However, younger male OA patients may have a lower revision rate with resurfacing than a THA. Additionally, a poster presented at the AAOS annual meeting last year identified higher blood cobalt and chromium levels in patients with unexplained failure of metal-on-metal hips.
