Osteochondritis Dissecans

Osteochondritis dissecans is a joint disorder of the subchondral bone, the bone layer just beneath the cartilage, in which cracks form in the cartilage and underlying bone after the blood supply to that area is disrupted, most often from repetitive overloading during running and jumping. Early on it causes pain during and after sports, while later stages bring swelling, joint catching and locking, and a crackling sensation called crepitus, with tenderness and fluid detectable on physical examination. In roughly half of cases the affected bone heals on its own; otherwise a fragment can separate and move freely within the joint, causing pain, blockage, and further damage. Treatment succeeds without surgery in about half of cases, while surgical options for the rest include arthroscopic drilling, securing loose cartilage flaps, or cartilage replacement, with children whose growth plates are still open generally recovering better because of their greater capacity for bone remodeling. It occurs in an estimated fifteen to thirty people per hundred thousand each year, most often in the knee, which accounts for about three-quarters of cases, and is an important cause of joint pain in active adolescents.