UK Bans Metal-on-Metal Hip Implants in NHS Hospitals

High failure rates and toxicity concerns have prompted the banning of metal-on-metal (MoM) hip implants in replacement surgeries performed at National Health Service (NHS, London, United Kingdom) hospitals.

The ban was issued following a guidance released to NHS hospitals by the National Institute for Health and Care Excellence (NICE; London, UK) in the wake of alarming results from recent studies showing that some MoM hip replacement brands, specifically the DePuy ASR, had failure rates as high as 43%. According to the NHS, data now suggest that large head MoM hip implants (those with a width of 36 mm or greater) wear down at a faster rate than other types of implants. As friction acts upon their surfaces, it can cause metal debris to break off and enter the space around the implant.

Over time, this can cause damage and deterioration in the bone and tissue surrounding the implant and joint, leading to the need for a revision surgery; of the 76,759 procedures performed in the UK in 2010, some 7,852 were revision surgeries. This led to the Medicines and Healthcare products Regulatory Agency (MHRA; London, UK) in 2012 to advise that larger types of MoM devices should be checked every year while the implant is in place. Previous guidelines issued in 2010 suggested larger MoM implants should only be checked annually for five years after surgery.

A further trigger for the ban are concerns that the debris could lead to metal ions, particularly cobalt and chromium, leaking in trace amounts into the bloodstream. While there has been no definitive link between ions from MoM implants and illness, there have been a small number of cases in which high levels of metal ions in the bloodstream were associated with symptoms or illnesses elsewhere in the body, including effects on the heart, nervous system, and thyroid gland.

“The figures speak for themselves: even the best metal-on-metals have four times the failure rate of the rest. This is a really significant problem because these were given to an awful lot of people,” said Stephen Cannon, an honorary consultant surgeon for the Royal National Orthopedic Hospital (Stanmore, UK), who welcomed the report. “I think there is a question about whether it goes far enough, but this is definitely a step in the right direction—it amounts to a ban on most of them.”

Meanwhile, in the United States, the Food and Drug Administration (FDA, Silver Spring, MD, USA) is busy gathering additional information about adverse events in patients with MoM implants, but has not yet made any regulatory decisions. At this time, the FDA advises patients with MoM implants who have no symptoms to attend follow-up appointments as normal with their surgeon. Patients who develop symptoms should see their surgeon promptly for further evaluation.

Related Links:
UK National Health Service
National Institute for Health and Care Excellence
Medicines and Healthcare products Regulatory Agency