March 15, 2012

The world’s largest artificial joint registry, the National Joint Registry of England and Wales, recommended this month that the use of metal-on-metal hip replacements be stopped, based on a study of the data involving more than 400,000 hip replacements between 2003 and 2011 that included data on more than 31,000 metal-on-metal hip replacements.

The study found that about 6% of people with metal-on-metal hip replacements needed surgery to repair or replace the implants after only five years, compared to between 1.7% and 2.3% for people who had a ceramic or plastic hip replacement joint. Hip replacements are expected to last at least ten years.

Earlier this month, the British agency responsible for medical device safety warned that patients with metal-on-metal hip replacements should have yearly blood tests for metals seeping into their blood and that these patients should also have MRI scans to check for muscle damage if they have pain, swelling, or reduced movement in order to determine if the hip replacements need to be removed.


The National Joint Registry of England and Wales reports that about 160,000 total hip and knee replacement surgeries are performed each year in about 400 hospitals in the UK. About two-thirds of the procedures are performed in National Health Service hospitals and the remainder are performed in hospitals not part of the National Health Service.

Hip Replacement Revision Rates

The National Joint Registry of England and Wales described the revision rates for hip replacements in its 8th Annual Report 2011. What follows are quotes from the Annual Report:

Overall revision rates were low: only 1.1% of primary hip replacements had been revised by one year after primary surgery rising to 2.3% by year three, 3.5% by year five, and 4.7% by year seven. However, there was substantial variation in revision rates according to prosthesis type with the lowest rates associated with cemented prostheses (3% at seven years) and the highest rates associated with resurfacing (11.8% at seven years) and stemmed metal-on-metal bearing surfaces (13.6% at seven years). There appears to be a sharp increase in the risk of revision at around six years after primary surgery for the metal-on-metal group although more data is needed to confirm this finding…

There was little substantive difference between the ceramic-on-ceramic, ceramic-on-polyethylene and metal-on-polyethylene groups. However, the risk of revision for metal-on-metal and resurfacing prostheses was considerably higher than for other bearing surfaces. Metal-on-metal was close to the revision rate for resurfacing (also metal-on-metal) up to six years after surgery but then appears to overtake the resurfacing revision rate. This is because of a sharp increase in the risk of revision at around six years for the metal-on-metal group…

Patients with metal-on-metal bearing surfaces comprise a relatively small group of the total hip replacements considered here (7.3%, with resurfacing accounting for another 7.1%). However, some studies have raised concerns about metal-on-metal implants in terms of higher revision rates and poorer patient outcomes (related to pain and function) compared with other bearing surfaces. In particular, there are concerns about the possibility of metal debris damage to soft tissue surrounding the joint (metallosis) and the uncertain effects of any release of cobalt and chromium ions into the patient’s blood. Attention has tended to focus on whether these problems could be associated with the use of large diameter head sizes and on particular designs such as the ASR implants (the ASR XL Acetabular Hip System and ASR Hip Resurfacing System) which were voluntarily recalled by the manufacturer DePuy in August 2010…

Clearly, the ASR results are noticeably worse than other groups by two years post surgery…

This indicates that for the cohort we have been observing (those who had a primary hip replacement since 1st April 2003), the highest incidence of revision was for metal-on-metal hips with 1.73 revisions per 100 observed years. This is another way of saying that there has been approximately one revision per 58 years of use for metal-on-metal hips. This compares with one revision per 70 years for resurfacing hips, one revision per 106 years for uncemented hips, one per 152 years for hybrid hips and one every 204 years for cemented hips. Of course, these incidence rates are likely to change as the risk of revision increases over time…


If you or a family member suffered unexpected complications or injuries as a result of hip replacement, knee replacement, or ankle replacement surgery in the U.S., a medical malpractice attorney may help you determine if you are entitled to compensation for your losses.

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