Fehlerhafte ASR Hüftprothesen der Firma DePuy werden in Europa seit August 2010 zurückgerufen. Die Durom-SHG hat erste Informationen für Betroffene mit einer ASR-Hüftprothese von DePuy zusammengestellt.
What are the concerns with metal-on-metal implants?
In late 2009 the DePuy ASR MoM implants were withdrawn from the Australian market after analysis of data from the AOANJRR – external site demonstrated that the rate of early revision surgery for these implants was high relative to other hip replacements. Monitoring of all MoM hip implants, to date, has not revealed a general problem with all MoM hip implants. However, there are concerns about MoM hip implants and the possibility of adverse health consequences of metal particles and metal ions that may be generated by wear of the components of these implants. For example:
- Medical Device Alert: All metal-on-metal (MoM) hip replacements (MDA/2012/008) – external site, MHRA, 28 February 2012
- Concerns about Metal-on-Metal Hip Implant Systems – external site, US Food and Drug Administration, February 2011
- Metal on Metal Hip Replacements – The Facts – external site, British Orthopaedics Association, (not dated – last accessed June 2012)
- Metal-on-metal Hip Implants – Information for Orthopaedic Surgeons Regarding Patient Management Following Surgery – external site, Health Canada. 9 May 2012.
Even though the physical wear rate of MoM hip implants is low, the body’s natural joint lubricating fluid can react with metal ions or metal particles that may be produced around the implant. Where this occurs, the surrounding tissue can be affected leading to pain and inflammation and ultimately to the need for replacement of the implant. This type of local reaction can be a cause of premature failure of MoM hip implants. Furthermore, the extent of local soft tissue damage can increase over time increasing the risk of complications with revision surgery. There is also concern that chromium and cobalt ions from a wearing MoM implant can enter the blood stream and that this may lead to side effects in other areas of the body. There are a small number of individual case reports about health problems being experienced by patients with MoM Implants1, 2. These do not establish a definitive link between the use of metal-on-metal implants and the symptoms. Therefore there is insufficient evidence at this time to demonstrate that MoM hip implants produce side effects beyond those that may occur at the site of implantation. A study from the United Kingdom did not find an association between having a MoM hip joint and an increased risk of cancer.3 Work is underway internationally to determine if a link exists between MoM hip implants and systemic toxicity, and in particular what levels of cobalt and/or chromium in the blood are likely to be associated with any such effects. The TGA is actively monitoring international developments in this area.
Implant design, its alignment during surgery and selecting the appropriate implant for the individual patient plays a large role in determining the ultimate outcome. Some MoM implants with large diameter femoral head components used in conventional total hip replacements have experienced relatively high rates of revision. Use of these large femoral head implants for total hip replacements is declining although they may still have advantages for some patients. Resurfacing surgery with small femoral head sizes has similar problems. Importantly, the revision rate of many MoM implants is currently comparable to other types of hip implants.