Metal-on-metal hip implants: Information for patients
20 September 2012
While the use of metal-on-metal hip implants is in decline in Australia some surgeons may still offer these implants because such a device may be considered the best treatment for a particular patient.
TGA is aware that the public may be concerned about these implants as a result of reports in the media about potential problems with metal-on-metal hip implants. These reports relate to whether the implants release trace amounts of the metals cobalt and chromium into the tissues surrounding the implant and also into the blood stream and if so, does this cause harm.
TGA is providing this information to the public (and more detailed information to health professionals) so people can make informed choices about their hip implant options and are aware of the role of the TGA in monitoring and regulating these medical devices.
Benefits: A metal-on-metal hip implant might be preferred by a surgeon depending on the individual needs of the patient. If the surgeon performs a resurfacing hip replacement procedure then a metal-on-metal device will almost always be used. A resurfacing surgery involves placing a cap over the existing thigh bone (femur) head rather than replacing the entire head of the bone and is therefore less invasive than a full hip replacement surgery. Metal-on-metal hip implants also have useful properties such as good durability.
Surgical practice has changed in response to emerging knowledge of what causes poor performance with some metal-on-metal hip implants. Also regular follow-up - including ongoing imaging and blood tests can help reduce the risk of the implant posing a health risk to the patient.
Risks: There is a growing body of evidence that because the two moving parts of a metal-on-metal hip implant wear against each other they can release trace amounts of chromium and cobalt, especially during the first 18-months or so after the operation. This leaching leads to an increase in chromium and cobalt in the blood and tissues at a low, stable level. If the amount of wear is too great, then the body may not be able to excrete the extra cobalt and chromium quickly enough. In some patients this can lead to high levels of those metals in the tissues surrounding the implant. If that happens, hip or thigh pain will usually develop. High blood levels of chromium and cobalt may also be observed.
While it is recognised that the ongoing release of cobalt and chromium can lead to problems around the joint it is not known how often these metals find their way into other parts of the body, and precisely how much of either is a toxic amount. Cobalt and chromium have been reported to be associated with problems in other parts of the body of some patients with metal-on-metal hip implants, but the small numbers of such reports has not provided the TGA with enough evidence to establish a link between those health problems and the use of metal-on-metal implants.
Most implanted medical devices have a limited life in the human body and may have to be replaced at some point. However it is important to ensure that implants do not require replacement too often or too soon after implantation and that any side effects are minor compared to the health benefits of having the implant.
TGA works closely with Australia's National Joint Replacement Registry which tracks all hip, knee and shoulder joint surgeries, including ones involving replacement of metal-on-metal hips. Information from this registry shows which implants are being replaced sooner than expected.
TGA works with a committee of Australian orthopaedic surgeons, known as the Orthopaedic Expert Working Group, to analyse and provide advice to the TGA about the data from the joint replacement registry. This group of surgeons has been involved with TGA in considering the specific concerns with metal-on-metal hip implants. We have also collaborated with regulatory authorities in the USA, UK and Canada on the issue.
As of 1 July 2012, the TGA upgraded its requirements for approval of all hip, knee and shoulder implants to the highest level (Class III). All metal-on-metal hip implants currently being supplied in Australia will be reassessed against the new requirements.
The TGA will continue to assess the safety, quality and performance of each metal-on-metal implant on a case-by-case basis. It will also closely monitor reports of adverse events as well as concerns raised about the performance of some brands, both in Australia and overseas. In addition it will continue to review relevant scientific and clinical literature.
On the basis of the available evidence and on the advice of our orthopaedic experts, the TGA recommends that patients with metal-on-metal hips implants be followed up regularly (at least annually in some cases) and that, in addition to soft tissue imaging such as ultrasound and/or MRI the follow-ups should include blood tests for cobalt and chromium.
The TGA is closely monitoring the issue of metal-on-metal hip implants. We will keep you informed if the situation changes, or as more information comes to light.
In the meantime, more detailed information about the TGA's current position on metal-on-metal hip implants (including advice to doctors and other health professionals) is available on the TGA website.
If you are not sure what type of hip replacement you have or if you have concerns about your hip replacement, you should seek information from the surgeon who performed the operation or the hospital where the operation was performed.
If you have a metal-on-metal hip replacement and have pain in your hip or thigh you should consult your general practitioner and/or your orthopaedic surgeon. Your GP/surgeon will usually order X-rays and may in some instances order further tests such as ultrasound, MRI and blood tests.
Consumers are encouraged to report any problems with your medical device and to ask your doctor to do the same - report any problems of this kind to us.
Content last updated: Thursday, 20 September 2012
Content last reviewed: Thursday, 20 September 2012
Web page last updated: Thursday, 20 September 2012