<unk>  is a relatively rare disorder, with an estimated incidence of 15 to 30 cases per 100,000 persons per year. Widuchowski W et al. found<unk>  to be the cause of articular cartilage defects in 2% of cases in a study of 25,124 knee arthroscopies. Although rare,<unk>  is noted as an important cause of joint pain in active adolescents. The juvenile form of the disease occurs in children with open growth plates, usually between the ages 5 and 15 years and occurs more commonly in males than females, with a ratio between 2:1 and 3:1. However,<unk>  has become more common among adolescent females as they become more active in sports. The adult form, which occurs in those who have reached skeletal maturity, is most commonly found in people 16 to 50 years old. While<unk>  may affect any joint, the knee—specifically the medial femoral condyle in 75–85% of knee cases—tends to be the most commonly affected, and constitutes 75% of all cases. The elbow (specifically the capitulum of the humerus) is the second most affected joint with 6% of cases; the talar dome of the ankle represents 4% of cases. Less frequent locations include the patella, vertebrae, the femoral head, and the glenoid of the scapula. The oldest case of<unk>  was identified on the temporo-mandibular joint of the Qafzeh 9 fossil.
Osteochondritis dissecans
Tennis elbow
Osteochondrosis
Osteochondroma
Myositis ossificans
Osteitis pubis
Osteitis fibrosa cystica
Synovial osteochondromatosis