Medically Reviewed by Rodney K. Alan, MD
Anyone researching hip joint replacements will eventually turn up the question of “Metal-on-Metal” (MOM) implants. In short, a hip replacement involves a ball-and-joint. The ball being the part placed in the leg and the joint or socket placed in the hip. For more information, see “9 Things You Should Know about Total Joint Replacement.”
“Truth is, all hip implants wear over time due to the constant movement in running and walking,” says McLeod Orthopedic Surgeon Dr. Rodney Alan. “Some people can live their entire lives after hip replacement without any problems. Others – generally about 10% of those with replacements will need surgery to remove or replace it. This is termed a revision.”
Traditionally, one surface was metal and the other a type of plastic. In the late 1990s, a newer version of the artificial joint was introduced with metal on both surfaces. The goal was to create a longer lasting joint, especially for young, active people.
A small number of the metal-on-metal joint recipients began to complain of these symptoms:
Investigation discovered deterioration in the tissue and bone surrounding the implant. In some patients, this damage caused the implant to loosen. It appears that the bodies of these recipients were reacting to the small metal particles – some so small they were “ions” – that wore off the joint.
How Often Is There a Problem?
Some specific designs have more problems than others. However, in general, the issue is a rare one. The US Food & Drug Administration has mandated continuing observation of the results on 21 brands of MOM joints. Ask your orthopedic surgeon is you have questions about a specific brand.
Several studies have looked at whether these metal ions could trigger cancer. The answer seems to be “no.” One study found that the overall cancer risk of metal-on-metal in hip patients was not higher than the general population. Another study stated flatly that there is no scientific evidence that cancer risk is increased in MOM hip recipients.
What if I have a metal-on-metal hip joint?
Keep an eye out for the symptoms mentioned above. If they appear, see your orthopedic surgeon. Even if you do not have symptoms, annual exams with your orthopedic surgeon are recommended so that the wear and metal ion concentrations can be monitored.
If you are experiencing other symptoms elsewhere in your body, report them to your primary care physician and mention that you have a metal-to-metal hip replacement.
What if I’m considering a hip joint replacement?
Talk with your orthopedic surgeon about your options. New developments are continually appearing in the area of total joint replacement.
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Sources include: McLeod Health, American Academy of Orthopaedic Surgeons, National Institutes of Health, National Health System (UK), British Medical Journal, US Food & Drug Administration