The goal of this clinical trial is to learn about preventing falls in people who have total knee replacement surgery using treadmill perturbation training. Perturbation training involves adjusting to rapid speed changes on a treadmill. The main questions it aims to answer are: * Does perturbation training improve the way that people who are planning to have total knee replacement surgery recover after treadmill test that reproduces a trip to the front or side? * Does perturbation training reduce the incidence of preventable gait-related falls during the first year after total knee replacement? Participants will: * complete surveys about their condition and fall history and take part in testing of walking ability and balance. * have a baseline gait analysis test to measure the motion of their body during normal walking. * Be randomized into two groups. One will receive fall-prevention literature. The other will receive the same literature and then take part in a two-week treadmill perturbation training program. * be contacted every two weeks for one year, and asked questions about whether they have fallen during that time. * wear a Fitbit activity monitor on their wrist for one year. Researchers will compare the number of falls from the group that only received literature to the treatment group to see if the training group has fewer falls during the year after surgery.