Joint injury and trauma dramatically increase the risk of developing osteoarthritis (OA). The purpose of this study is to determine what factors lead to decreased pain, improved joint function, and repair of the joint surface in post-traumatic OA.

Study hypotheses: 1) Ankle motion during distraction will result in clinically significant improvements in Ankle Osteoarthritis Scale scores, SF-36 scores, and improved cartilage thickness distribution over the habitually most heavily loaded portion of the articular surface, as compared to the use of distraction without ankle motion. 2a) Ankles with low geometric surface irregularity and greater range of motion will have better preservation of neo-chondroid tissue (increased normalized cartilage thickness and reduced longitudinal compressive strain in the habitually heavily regions of the articular surface) than those with high surface irregularity. 2b) Low geometric surface irregularity and greater range of motion will have reduced habitual focal or regional contact stress elevation. 3) Joints that have better improvements in Ankle Osteoarthritis Scale scores and improved cartilage thickness distribution over habitually heavily loaded portion of the articular surface will have improved normalization of synovial fluid markers of biosynthetic/degradative activity and oxidative stress.

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.

Participants in this study will be randomly assigned to one of two treatment groups. Group A will be treated with mechanical distraction with motion; Group B will be treated with mechanical distraction without motion. Participants will be followed for 28 months and will have 11 study visits. Most of the study visits will occur during the first half of the study. State-of-the-art techniques for clinical assessment, articular surface imaging, biomechanical modeling, and biochemical testing will be used in this study.

Inclusion Criteria:

• Symptomatic isolated ankle OA (unilateral Kellgren grade 3, 4, or 5)
• Skeletally mature (children included if they have no open growth plates)
• Failure of less than 1 year nonoperative treatment, including 3 months of continuous treatment with nonsteroidal anti-inflammatory agents and 3 months of unloading treatment (i.e., unloading brace, crutches, cane, walker)