<qa>  What is the purpose of this study?Little work has been done on the pathogenesis and prevention of post-traumatic OA. The human ankle joint provides a unique opportunity for the study of post-traumatic OA because of the low risk of primary OA and the relatively high risk of post-traumatic OA. This study involves a multidisciplinary approach utilizing both laboratory and clinical research to improve understanding of OA and to develop innovative approaches for preventing and treating this disease. Mechanical distraction involves operative placement of specialized pins and rods to hold the joint in place. Some distraction allows for limited motion of the joint, while other distraction holds the joint immobile. The purpose of this study is to elucidate the mechanical factors that lead to restoration of a cartilaginous articular surface, decreased pain, and improved joint function after mechanical distraction of osteoarthritic joints. 