Osteochondritis Dissecans of the Talus
This condition is one in which there is an injury to both the cartilage and the underlying bone. In the ankle region, the bone most commonly affected is the talus, which is the bone under the tibia and fibula, and above the heel bone (calcaneus).
Keeping in mind that a joint is where one bone meets another, and that most joints are covered with smooth cartilage on the surfaces where the bones touch each other, this condition occurs usually most often traumatically when the cartilage and underlying bone is injured, with fracture occurring, and possible displacement of the fragment.
Here are some examples of injuries to the talus, where both the cartilage on top and bone underneath are affected. Sometimes the piece can be loose, and sometimes it remains attached.
Usually, in cases where the symptoms continue despite periods of rest and immobilization (cast or walker boot), arthroscopic surgery is required to remove the loose piece. This procedure, where the arthroscope (a small telescope) is used to look into the ankle, involves removing the small piece and roughing up the surface from which the piece came to induce new cartilage to grow. This surgery is usually done on an outpatient basis.