This issue of Clinics in Sports Medicine will include the diagnosis and treatment of Osteochondritis Dissecans in athletes. Osteochondritis Dissecans, a joint condition in which a piece of cartilage, along with a thin layer of the bone beneath it, comes loose from the end of a bone. It is most common in the knee; however it can occur in other joints. Those individuals who frequently participate in strenuous sports, particularly young athletes, or perform repetitive activities that put the joint under stress, are at an increased risk of developing Osteochondritis Dissecans.