The total ankle arthroplasty procedure, more commonly known as an ankle replacement, is a relatively new procedure used to repair years of wear and tear resulting in end-stage osteoarthritis of the ankle joint. The purpose of this study is to compare ankle joint function and mobility in healthy patients vs. patients who have undergone total ankle arthroplasty. We will use a 18 camera Vicon system with a full body marker set and the Oxford foot model to closer analyze the motion of the foot/ankle. We will collect kinematics, ground reaction force, and EMG (muscle activation) data with the patients walking on a level surface, a surface tilted 15 degrees, and up and down stairs to stress the ankle and create variation in the internal foot joints. These data will be processed using Vicon Plug In Gait Model to calculate the joint angles and joint movements used in the patient's movements. We will use the kinematic data collected to find significant differences in the ankle joint movement of patients who have undergone total ankle arthroplasty. These results could be instrumental in understanding the impact of an ankle replacement on joint function and eventually, in determining which ankle procedure will allow patients the greatest mobility and comfort.