It's difficult to predict how long a joint replacement will last for several reasons. One is that it can take a decade or more to collect data on past operations to predict the success of future operations. Another challenge is that in recent years, there's been a tendency to operate on younger people, including baby boomers who are more active in their 50s and 60s and may expect more of their new joints than prior generations. Age is of particular importance, because a person with a life expectancy of 15 years has a much better chance of avoiding a future operation than a person with a life expectancy of 30 years. In addition, younger patients tend to be more active and put more stress on their new joint. For these reasons, some surgeons advise younger patients to put off surgery as long as possible, even if that means suffering with pain, stiffness, and reduced mobility.