A new investigative study by the British Medical Journal (BMJ) shows a potential for significant danger with all or most metal-on-metal hip implants. In addition to higher than average failure rates, the metal-on-metal implants can leach metal ions into the body that have the propensity to destroy a patient's muscles and bones, causing permanent disability. There is also a risk of genetic and nervous system damage from abnormal levels of metal ions.
Constant pressure between the ball and socket components of the implants can cause the release of metal debris and metal ions. Hexavalent chromium, one particular type of metal ion potentially released from these implants, is labeled as a known carcinogen by the World Health Organization. Trivalent chromium, a potential carcinogen, and cobalt, a probable carcinogen, may also be released from these implants.
Additionally, metal-on-metal hip implants have a higher than average failure rate. DePuy recalled its ASR implant in 2010 following startling findings that the metal-on-metal implants could cause serious harm due to failure. When a metal-on-metal hip implant is used for hip resurfacing, the failure rate is 11.8 percent at 7 years. The rate jumps to 13.6 percent at 7 years for metal-on-metal total hip replacement. The average failure rate ranges from 3.3 percent to 4.9 percent at 7 years for hip implants that are not metal-on-metal, according to the 8th Annual Report of the National Joint Registry.
Many patients still have metal-on-metal implants in the U.S. It's important for patients to fully understand the potential risks involved with these devices. Contact our office if you or a loved one experienced a hip replacement failure or hip implant complication.
Source: BMJ/BBC Newsnight, "How safe are mental-on-metal hip implants," Deborah Cohen, 2/2012