What factors determine how long a hip or knee replacement will last?
Hip and knee replacements can last between 10 and 20 years, but in certain senses they are similar to a car. It depends on how many miles you’ve put on it (how much it’s used), and part of that depends on size and age. So if you’re young and you’re working, you might go through a hip or knee replacement much faster than if you’re older, retired and not rushing back and forth to work every single day.
A well performed hip replacement that is done when you’re older might last for 20 years because you put much less stress on it, and a hip replacement done on people who are younger, working full-time and maybe chasing their kids around during the rest of their time, might only last for closer to 10 years.
There are some other factors that come into play as well in determining how long such a joint replacement may last. If you’re obese or overweight, the extra pounds adds to the wear and tear of that hip or knee replacement, which makes it last for less of a period of time.
How long should we hope our joint replacement will last?
One recent study on the long-term outcomes of a commonly used knee replacement found the implant to still be functioning in 96 percent of patients 20 years after being implanted. This is certainly one of the better reports, as other studies have not necessarily shown that level of success.
However, the goal of a knee replacement should be to achieve several decades of a functioning knee. You should remember that while some patients may have knee replacements that last several decades, other patients may require a repeat knee replacement just a handful of years after their surgery. Revision knee replacement (a second knee replacement) is a major undertaking that often has less successful results than an initial knee replacement. Implant manufacturers are constantly striving to create a "better" implant that will last longer. Some of these implants have only been used for a handful of years, and determining whether or not they will last longer is a question only time can answer.
It may seem obvious, but there are some specific medical conditions that can lead to complications affecting the joint replacement. Patients having any invasive medical procedures (including dental work) may require antibiotic treatment to prevent bacteria from getting into the joint replacement. Patients with osteoporosis should ensure they are being adequately treated as a fracture in the bone around a joint replacement can affect the functioning of the implant.