Health Canada has issued new advice for doctors on how to manage patients with metal-on-metal hip implants.
The department is also alerting patients with the implants of trouble signs associated with the devices.
There has been a multitude of reports of problems with metal-on-metal hip implants internationally, with one major manufacturer recalling its product last year.
The U.S. Food and Drug Administration has even asked manufacturers to conduct safety studies on the devices.
Health Canada said earlier this year that metal-on-metal devices make up only about 10 per cent of replacement hips used in this country.
The department says people with these implants should be on the lookout for pain in the groin, hip or leg, swelling at or near the hip joint, or onset of a limp or change in walking ability or limited range of motion.
The department suggests the people who seem most likely to be affected are women, physically active patients, patients who are severely overweight, or those with implants in both hips.
Metal particle blood tests
In an advisory to patients, Health Canada says the thinking is that tiny metal particles or metal ions may wear off the device over time and patients may be reacting to them.
In its advice to doctors, Health Canada says only surgeons trained to perform metal-on-metal hip implant procedures should do this type of work.
It suggests doctors faced with patients who may be reacting to the devices should consider ordering whole blood or serum tests for cobalt and chromium metal ion levels.
But it acknowledged there could be problems interpreting data from those tests, because there are no approved standardized tests and readings could differ from laboratory to laboratory.
As well, there's no consensus on what level of metal ions in the blood is too high or when action should be taken.
The department is advising doctors that patients who receive metal-on-metal hip implants should be followed annually for five years and then afterwards on a schedule that meets the locally agreed practice.
But patients who are at higher risk of developing problems with these devices should be followed more closely, Health Canada says.