Most physicians regard radiography of the ankle joint as a rather mundane subject, especially if the history indicates a traumatic episode and study of the films reveals no evidence of a fracture. The purpose of this communication is to stimulate interest in this subject and to demonstrate how ankle arthrography can be utilized in the study of ankle sprains to delineate the pathologic anatomy. This should contribute to the better treatment of these injuries. Review Of Literature Little on the subject of ankle arthrography has appeared in the American literature. Berridge and Bonnin (2) in 1944 discussed ankle arthrography and pointed out its value in the diagnosis of rupture of the tibiofibular syndesmosis. They did not feel that the procedure had a wide sphere of use and preferred radiography of the joint with strain under general anesthesia for testing the integrity of the medial and lateral ligaments. Almost everything of value on ankle arthrography is to be found in the European literature. The most useful articles on the subject and the ones that aroused my interest are by Arner and his associates (1) and by Broström et al. Arner performed a postmortem study to establish the range of normal findings encountered in ankle arthrography, and he also discussed four cases in which surgical verification of the arthrographic findings was obtained. Broström's 4 articles (3–6) discuss all aspects of ankle sprains and the radiographic evaluation of these injuries, including the use of positive contrast arthrography. He studied 321 consecutive ankle sprains with arthrography, and 239 of these patients had extra-articular leak of the contrast medium. Subsequent surgery was performed in 101 patients with verification of the arthrographic findings. This represents a well controlled study on the accuracy and value of ankle arthrography. Anatomy The ankle is a compound joint formed by the tibia, fibula, and talus. The joint capsule is attached at the bone-cartilage border of these bones. Anteriorly and posteriorly the capsule is lax and forms prominent recesses that allow plantar flexion and dorsiflexion at the joint. Laterally and medially the capsule is taut and reinforced by ligaments. The ankle and subtalar joints have many ligaments in common and function as a single unit, allowing pronation and supination of the foot. The ligaments of the ankle are the structures of interest in this discussion and will be described in detail. Laterally three distinct ligaments are present. The anterior talofibular ligament runs from the anterior margin of the lateral malleolus to the neck of the talus. The inner surface of this ligament is covered by synovial membrane, reflecting the close association of the joint capsule to the overlying ligament.