People who've had certain metal-on-metal hip implants are more likely to need the artificial joints replaced compared with more traditional hip implants, according to a new Canadian report.
Hip replacements are one of the most commonly performed surgical procedures and are meant to improve quality of life for patients with degenerative arthritis of the hip. But people who undergo a second total hip replacement face longer recovery periods, which increases hospital stays and costs to the health-care system.
After research studies suggested that those using a metal ball and a metal cup are more than three times more likely to fail and can cause tissue damage around the joint, regulators in the U.K., U.S. and Canada issued safety alerts because tiny metal particles may wear off the device and enter the bloodstream.
On Thursday, the Canadian Institute for Health Information released its report looking at the factors influencing how long artificial hip implants lasted based on voluntary data for 56,942 surgeries that were performed in all provinces except Quebec from 2003 to 2011.
In Canada, more than 40,000 total hip replacements are performed every year.
Use of metal-on-metal implants has declined since its peak in 2007-2008.
Patients with a specific type of metal-on-metal hip replacement (large-diameter modular implants) had a 5.9 per cent chance of needing a second implant within five years compared with 2.7 per cent chance among those with the most common type of metal-on-plastic implant (metal-on-cross-linked polyethylene), the institute reported.
The large diameter versions contain a metal ball inside a larger-than-average metal socket. Until a couple of years ago, they made up about three per cent of hip replacements, mostly for younger patients, who need a hip to last longer than the typical 10 to 15 years.
Dr. Tom Turgeon, an orthopedic surgeon in Winnipeg, said metal-on-metal hips are only used in few circumstances now.
It's unclear why metal-on-metal implants are more likely to fail, Turgeon said.
The most common types of hip implants in the study were:
- Metal-on-plastic — 73 per cent.
- Metal-on-metal — 9 per cent.
- Ceramic-on-ceramic — 8 per cent.
- Ceramic-on-plastic — 5 five per cent.
People who have had the large-diameter modular type of metal-on-metal artificial hip implants or who have other risk factors — such as a pre-existing long-term medical condition — may not necessarily require an early replacement but could be at higher risk of needing one.
The data also suggested that patients whose hips were replaced with a metal-on-metal implant were most likely to be male and younger than age 55.