March 14, 2012

Experts Say Metal On Metal Hip Replacements Need To Be Banned

According to a new study published in the Lancet journal, there is unequivocal evidence of high failure rates of metal on metal hip replacements, especially in women.

The data showed that on more than 400,000 hip replacements, metal on metal types needed revising more often than other types. Those found in women were especially prone to failure.

The researchers say that tiny metal ions, made of cobalt and chromium, break off the implant and leach into the blood. This causes muscle, bone and possibly neurological damage.

The British Medicines and Healthcare products Regulatory Agency (MHRA) issued new guidelines for the devices, according to the Guardian, 50,000 patients in the UK will need to have annual MRI´s and frequent blood checks, for heavy metals in the blood.

The research found that metal to metal hip replacements have a five-year revision rate of 6.2 percent. Whereas ceramic on ceramic devices have a 2.3 percent five-year revision rate. And plastic on metal types only have a 1.7 percent revision rate.

The study found that devices with a bigger head failed quicker. They found a 2 percent increase in risk of failure with every 1mm increase in head size, whereas ceramic types had lower failure rates with bigger head size.

The study followed more than 31,000 metal on metal implants given to patients between 2003 and 2011 following the devices progress over seven years.

According to the study at seven years after surgery, revision rates for 55 year-old women with 46 mm heads were as high at 10 percent, whereas with a 36mm head the revision rate was 8.4 percent.

At five years after surgery 55-year old women with 46mm heads had a revision rate of only 6.1 percent. Those with a 28mm metal on plastic implant had a revision rate of only 1.6 percent.

As for men, those aged 60 and had metal on metal implants, revision rates were 3.2 percent with a 28mm head and 5.1 percent  for the larger 52mm head.

The Guardian reports that metal on metal hip replacements are on the decline in England  and Wales, whereas in the US it is found they are used frequently.


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