Osteochondritis dissecans is a rare bone disease that involves an acquired necrotic lesion in the subchondral bone, leading to the formation of loose bodies in joints. It primarily affects the knee, ankle, and elbow joints, causing pain, functional limitations, and potential secondary osteoarthritis. The condition occurs when a piece of cartilage and bone detach from the end of a bone, resulting in symptoms like pain, weakness, and decreased range of motion. In some cases, the exact cause is unknown, but familial cases are linked to changes in the ACAN gene. Symptoms may include pain during and after sports, joint swelling, catching, and locking during movement. Early stages may only show pain, while later stages can present with effusion, tenderness, and a crackling sound with joint movement. Osteochondritis dissecans is characterized by cracks in the articular cartilage and subchondral bone, with physical examination revealing various symptoms depending on the stage of the disorder.