Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Osteochondritis dissecans ?
    ### Response:
    Osteochondritis dissecans is a joint condition that occurs when a piece of cartilage and the thin layer of bone beneath it, separates from the end of the bone. If the piece of cartilage and bone remain close to where they detached, they may not cause any symptoms.
    