02.17.11
As the American Academy of Orthopedic Surgeons (AAOS) kicks off its annual meeting in San Diego, Calif., much of the talk undoubtedly will be about metal-on-metal implants and the most recent machinations surrounding the technology. The implants have been widely used for years to replace joints damaged by the ravages of time, trauma and arthritis.
The U.S. Food and Drug Administration (FDA) recently launched a webpage detailing some of the issues surrounding metal-on-metal implants, and agency officials said they are taking a close look at all-metal hips, which have faced sales pressure amid concerns about metal particles wearing off and causing medical problems. Some patient advocacy groups have laid blame at the FDA's feet, accusing the agency's review process of being too lax.
As a consequence of the sliding action of joint replacement devices, wear particles form in the joint space. Implant, design and materials selection can limit the concentration and size of the particles that develop during the expected life cycle of the implant, but essentially it is unavoidable. It is the presence of the wear particles, at certain concentrations and specific size ranges, that largely contributes to osteolysis (bone cell death) through various cell responses in the body. The formation of wear debris undoubtedly has created considerable concern about the long-term longevity of implants.
For this reason, the FDA requires manufacturers to show the wear particle size, shape distribution and concentration development during biomechanical testing. They must demonstrate that the particles produced are outside of the bioactive size range and also are of low concentration.
The agency said it's "actively working in several areas to further assess the safety and effectiveness" of the devices.
The agency also made detailed recommendations to surgeons, such as avoiding all-metal implants in patients with certain problems like suppressed immune systems or known metal sensitivity. People react to metal particles differently, and it's not currently possible to predict who will have a reaction, what it will entail or when it could happen, according to the FDA. The agency recommended patients with all-metal hips talk to their surgeon right away if they develop new or significantly worsening problems like pain, swelling, numbness and walking issues.
In August last year, Johnson & Johnson's (J&J) DePuy orthopedic division issued a voluntary recall of its ASR metal-on-metal implant after new data from a joint registry in the United Kingdom indicated an unusually high rate of repeat procedures. Zimmer Holdings Inc. suffered a blow in mid-2008 when it suspended U.S. sales of a metal hip cup called Durom amid reports of issues like cup loosening, which the company pegged to surgeons needing retraining. Biomet Inc., which is privately held, also manufactures a metal-on-metal hip.
All-metal hips most often are constructed of cobalt-chromium alloy.
Stryker Corp. doesn’t make all-metal hips. Zimmer still does, though company officials have said it is not a big business for them. Stryker and Zimmer both have reported upticks in their non-metal hip business as a result.
AAOS issued a statement thanking the FDA for its "thorough and well-considered look” at concerns surrounding the implants.
"The FDA is a partner in patient safety and education. We believe that a significant majority of metal-on-metal hip replacement implants have successfully relieved pain and improved function without any problems for the patients who have received them but there have been some concerning exceptions," John Callaghan, the academy's president, said in a release. "We are working together to investigate and report these concerns and will continue to communicate with our 36,000 members, the medical community and the public.” In Callaghan's disclosure, he reported receiving royalties from DePuy.
According to data from the Nationwide Implant Sample database, in a one-year period from 2005-2006, approximately 39,200 MoM hip replacements were performed.
The Academy has helped to establish the American Joint Replacement Registry (AJRR). The AJRR will track data on outcomes and devices, just as joint registries in other countries do. This national database will serve as an early alert system for continued or new device problems. The data collection process has just begun and will allow orthopedic surgeons to track the success and failures of any implant used nationwide, according to AAOS officials.
Data from a recent study performed by DePuy indicated that as many as 12 percent of patients who received ASR implants through a replacement or resurfacing required corrective surgery in fewer than five years after their initial surgery due to a failure of the component device. This is much sooner than the average follow-up procedure, which occurs roughly 15 to 20 years after implantation.
The problem with more frequent revisionary surgery is that every surgery has risks, and every additional surgery involving the hip joint exponentially increases the chances of serious complications like blood clots, bone loss, nerve damage or infection. Of course, there also is the associated pain, rehabilitation time, and expense.
In early 2010, DePuy reported that it would phase out these implants because not enough of the devices were selling to justify the costs of manufacture. Consumer watchdog groups and medical professionals, however, feel that DePuy's announcement was motivated by its own misgivings about the problems with the device.
The most common complication associated with these particular ASR implants is something called metal hypersensitivity. Surface sensitivity to metals is relatively common. An estimated 10 to 15 percent of the population has some form of allergic reaction to metal, from hives, redness and itching to eczema in the affected area.
The metal sensitivity experienced by hip replacement patients cannot be treated by an analgesic cream or a topical antihistamine. The problem occurs when metal-on-metal devices are either installed incorrectly or they fail altogether—causing the metal surfaces to scrape together with more friction than normal, releasing microscopic particles of metallic debris into nearby tissue.
A buildup of this metal can cause inflammation, pain in the groin region, bone loss, systemic immunological responses and tissue death. These serious complications often require the revisionary surgery referenced above to correct tissue problems or even swap out the faulty joint for a new one. That is why medical professionals have recommended—in a recent edition of The Journal of Arthroplasty—that physicians only use these particular ASR devices once they have carefully considered the possible benefits and risks to the patient.
The U.S. Food and Drug Administration (FDA) recently launched a webpage detailing some of the issues surrounding metal-on-metal implants, and agency officials said they are taking a close look at all-metal hips, which have faced sales pressure amid concerns about metal particles wearing off and causing medical problems. Some patient advocacy groups have laid blame at the FDA's feet, accusing the agency's review process of being too lax.
For this reason, the FDA requires manufacturers to show the wear particle size, shape distribution and concentration development during biomechanical testing. They must demonstrate that the particles produced are outside of the bioactive size range and also are of low concentration.
The agency said it's "actively working in several areas to further assess the safety and effectiveness" of the devices.
The agency also made detailed recommendations to surgeons, such as avoiding all-metal implants in patients with certain problems like suppressed immune systems or known metal sensitivity. People react to metal particles differently, and it's not currently possible to predict who will have a reaction, what it will entail or when it could happen, according to the FDA. The agency recommended patients with all-metal hips talk to their surgeon right away if they develop new or significantly worsening problems like pain, swelling, numbness and walking issues.
In August last year, Johnson & Johnson's (J&J) DePuy orthopedic division issued a voluntary recall of its ASR metal-on-metal implant after new data from a joint registry in the United Kingdom indicated an unusually high rate of repeat procedures. Zimmer Holdings Inc. suffered a blow in mid-2008 when it suspended U.S. sales of a metal hip cup called Durom amid reports of issues like cup loosening, which the company pegged to surgeons needing retraining. Biomet Inc., which is privately held, also manufactures a metal-on-metal hip.
All-metal hips most often are constructed of cobalt-chromium alloy.
Stryker Corp. doesn’t make all-metal hips. Zimmer still does, though company officials have said it is not a big business for them. Stryker and Zimmer both have reported upticks in their non-metal hip business as a result.
AAOS issued a statement thanking the FDA for its "thorough and well-considered look” at concerns surrounding the implants.
"The FDA is a partner in patient safety and education. We believe that a significant majority of metal-on-metal hip replacement implants have successfully relieved pain and improved function without any problems for the patients who have received them but there have been some concerning exceptions," John Callaghan, the academy's president, said in a release. "We are working together to investigate and report these concerns and will continue to communicate with our 36,000 members, the medical community and the public.” In Callaghan's disclosure, he reported receiving royalties from DePuy.
According to data from the Nationwide Implant Sample database, in a one-year period from 2005-2006, approximately 39,200 MoM hip replacements were performed.
The Academy has helped to establish the American Joint Replacement Registry (AJRR). The AJRR will track data on outcomes and devices, just as joint registries in other countries do. This national database will serve as an early alert system for continued or new device problems. The data collection process has just begun and will allow orthopedic surgeons to track the success and failures of any implant used nationwide, according to AAOS officials.
Data from a recent study performed by DePuy indicated that as many as 12 percent of patients who received ASR implants through a replacement or resurfacing required corrective surgery in fewer than five years after their initial surgery due to a failure of the component device. This is much sooner than the average follow-up procedure, which occurs roughly 15 to 20 years after implantation.
The problem with more frequent revisionary surgery is that every surgery has risks, and every additional surgery involving the hip joint exponentially increases the chances of serious complications like blood clots, bone loss, nerve damage or infection. Of course, there also is the associated pain, rehabilitation time, and expense.
In early 2010, DePuy reported that it would phase out these implants because not enough of the devices were selling to justify the costs of manufacture. Consumer watchdog groups and medical professionals, however, feel that DePuy's announcement was motivated by its own misgivings about the problems with the device.
The most common complication associated with these particular ASR implants is something called metal hypersensitivity. Surface sensitivity to metals is relatively common. An estimated 10 to 15 percent of the population has some form of allergic reaction to metal, from hives, redness and itching to eczema in the affected area.
The metal sensitivity experienced by hip replacement patients cannot be treated by an analgesic cream or a topical antihistamine. The problem occurs when metal-on-metal devices are either installed incorrectly or they fail altogether—causing the metal surfaces to scrape together with more friction than normal, releasing microscopic particles of metallic debris into nearby tissue.
A buildup of this metal can cause inflammation, pain in the groin region, bone loss, systemic immunological responses and tissue death. These serious complications often require the revisionary surgery referenced above to correct tissue problems or even swap out the faulty joint for a new one. That is why medical professionals have recommended—in a recent edition of The Journal of Arthroplasty—that physicians only use these particular ASR devices once they have carefully considered the possible benefits and risks to the patient.