The investigators propose a new method of exercising following knee replacement surgery. This method involves using a commercially available game system to promote "re-loading" of the surgical limb. The game system has games designed to allow the person playing to move objects or characters on a screen by shifting his/her weight from one leg to another while standing on an instrumented "balance board". The investigators have developed an exercise program to promote shifting weight to the surgical limb, by choosing appropriate games and manipulating the goals of those games. It is the investigators' hypothesis that early application of this surgical leg "re-loading" intervention after knee replacement will result in meaningful improvement in physical function by improving movement symmetry.