Caption

Ankle disease. Coloured X-ray of the ankle of a patient with osteochondritis dissecans (OCD) of the talus (ankle bone, centre). OCD affects the talus at the joint with the tibia (shinbone, top). It occurs when a small fragment of cartilage and bone separates from the joint, most often after a twisting injury. The fragment may stay in place or fall into the joint, where it causes swelling and pain, and may cause the joint to lock. If the fragment is still in place treatment is with rest, but if it has moved surgery may be needed.