3D X-ray Motion Analysis of Ankle-foot Motion After Total Ankle Arthroplasty

15 study participants will include those using a Stryker STAR prosthesis and a Wright Medical INBONE 2 prosthesis and a group of matched control subjects. CT scans of lower limb anatomy (ankle-foot complex) will be obtained for all subjects to be converted into 3D bone surface models for use in the joint motion tracking software. Each participant will participate in one day of data collection with an X-Ray Motion Analysis (XMA) system. High-speed biplanar XMA system will capture video images of the skeletal motions within the foot-ankle complex during normal movement. Subjects will walk and perform controlled movements in the capture volume within the XMA system. Following data collection, the 3D bone surface models will be mapped to the sagittal (side view), coronal (front view), and axial (top view) plane skeletal motions demonstrated in the collected x-ray videos. Motion tracking data will then be used to accurately animate the 3D bone models to demonstrate the active range of ankle-foot joint motions during voluntary movement and gait. Resulting range of motion measurements in dorsiflexion/plantarflexion, internal/external rotation, and inversion/eversion will be used to determine the extent to which normal motion in the ankle-foot complex has been restored in ankle prosthesis users.