Biomechanical domain: Instrumented gait analysis will be performed on each subject. Reflective markers will be placed on each subject's head, hands, arms, trunk, legs, and feet. The subject will walk along a 12 m walkway with embedded forceplates. The motion of the markers will be collected with a 10 camera Vicon 612 system and processed to determine the motion of the ankle joint in three planes as well as the moment and power generated by the ankle during walking. This will allow us to assess the technical functional of the ankle joint, the range of motion used during gait and the moment, power and energy contribution of the ankle during walking for each of the treatments. Gait assessments will occur prior to surgical intervention and at 12, 24, and 36 months post-op. Gait assessment takes place at the VA Puget Sound Health Care System in Seattle, WA. The investigators will only recruit subjects from the VA and Harborview Medical Center for the gait analysis portion of the study.