A total knee replacement can last from 15 to 20 years. A knee replacement done today would have a 90 to 95 percent chance of lasting 10 years, and an 80 to 85 percent chance of lasting 20 years. The longevity of a knee replacement is also part of the patient’s responsibility. Patients should follow their doctor’s instructions after surgery and take care of their general health to add to the life of their knee replacement