Osteochonritis dissecans (sometimes spelled dessecans, and abbreviated "OCD") is a painful condition within a joint of the body in humans or animals, in which fragments of cartilage or bone have become loose within a joint, leading to pain and inflammation. These fragments are sometimes referred to as "joint mice" due to a squeaking sound sometimes resulting from the joint. Specifically, OCD is a type of osteochondrosis in which a lesion has formed within the cartilage layer itself, giving rise to secondary inflammation. It has a complex etiology, and can be caused by genetic, hormonal, environmental and nutritional factors.