Total knee and total hip implants have a limited life. Most doctors tell their patients to expect the implant to last 10 to 15 years. How long they last really depends on use, not time. Researchers are studying how active patients are and how this affects the implant.
The question asked in this study was how many days of study are needed to measure activity. They compared number of steps taken (walking) on four days and compared it to a sampling over seven days.
They found the level of activity recorded over four days is just as good as counting the number of steps taken over seven days. Researchers will be able to use this information to set up future studies of joint implants. Changes in activity from season to season and year to year will be studied next.