Ankle osteoarthritis is characterized by joint pain, tenderness, limitation of movement, and variable degrees of inflammation. These factors combined and left untreated will severely limit a person's mobility and willingness to participate in activities. Two common surgical procedures chosen to alleviate pain and to increase mobility are ankle arthrodesis (ankle fusion) and arthroplasty (ankle replacement). Success rates for these procedures are variable and the amount of information available regarding long-term follow-up is limited. The extent to which a person is able and willing to move around the world is often an indicator of his/her condition. The proposed study will examine walking activity levels, and any difference in activity, in patients immediately before and after undergoing surgical treatment for ankle arthritis.