On average, a total knee replacement lasts between 15 to 20 years after surgery, according to the American Association of Hip and Knee Surgeons. The association bases this average on how many total knee replacements fail per year, and the annual failure rate is between 0.5 and 1 percent, according to its assessment of available data.
Most people who have a total knee replacement have a 90 to 95 percent chance of the replacement lasting 10 years and an 80 to 85 percent chance that the replacement lasts 20 years, with the potential for replacements lasting longer as joint replacement technologies improve, notes the American Association of Hip and Knee Surgeons.
In patients younger than 65, a knee replacement might not last as long as it does in patients over 65 due to more mechanical stress put on the implant, states the American Academy of Orthopaedic Surgeons. An examination of the literature on total knee replacement arthroplasty in patients under the age of 65 who underwent surgery due to underlying conditions such as rheumatoid arthritis or skeletal dysplasia showed that about 1 percent per year needed to have another surgery performed over a follow-up period of 10 or fewer years. In the April 2012 issue of AAOS Now, rheumatoid arthritis patients under the age of 65 who had low-activity lifestyles were reported to have a 100 percent success rate, with implants lasting up to 15 years.