original_query: What is osteochondritis dissecans (OCD) and what are its primary effects on the joint?
query: What is osteochondritis dissecans (OCD) and what are its primary effects on the joint?
answer: Osteochondritis dissecans (OCD) is a joint disorder where cracks form in the articular cartilage and underlying bone, primarily affecting the subchondral bone.  Primary effects include pain (especially after sports), swelling, catching and locking of the joint during movement, and potential fragmentation of bone and cartilage within the joint space, leading to further damage and instability.