Patients often ask, “How long will knee replacements last?” This is an excellent question, and particularly relevant for those who are younger and contemplating knee replacement.
More than 600,000 knee replacements will be performed in 2017 and the number is due to rise to 2.2 million by 2020. Knee replacements reduce pain and improve function, and allow people to maintain a level of activity for as long as their overall health allows. Total knee replacement (TKA) does not, however, give you a normal knee and it is important for patients to have realistic expectations.
I tell patients that TKAs are mechanical devices, much like a set of tires, and they begin to wear out the day you put them in. Like tires, a number of factors contribute to the longevity of the implants. It is important to consider what long-term data is available for a particular model of implant, particularly when considering a “new” technique or device. Most of the major implant companies and common implant models have very solid 15 to 20 year follow-up information that finds that greater than 90 percent of implants are still functioning after 15 to 20 years of use. Given some of the material advances in the last 10 years, I am optimistic that implants currently being used will actually last closer to 30 years, but we need additional time and follow-up to be certain.
In summary, patients who take good care of their new knees - i.e. avoid running, jumping, heavy physical activity and have a well aligned, flexible knee - should enjoy 20 or more years of reliable service. Factors - such as excessive patient weight, large deformity and/or poor alignment, and unwise activity choices - may shorten the lifespan of a new knee replacement.