Osteochondritis dissecans of the knee is most common. There are also cases of osteochondritis dissecans of the elbow or ankle. Very few patients have osteochondritis dissecans in other joints. Usually, this condition affects one joint at a time.
Osteochondritis dissecans is most common in growing children, ages 8–16, who are very active in sports. It often starts as a mild, aching pain that can get worse over time. The pain may occur after an injury or trauma to a joint. Without treatment, osteochondritis dissecans can lead to further joint damage and early development of osteoarthritis.

Figure 1: An X-ray of a typical knee compared to a knee with osteochondritis dissecans.
What are the Causes of Osteochondritis Dissecans?
Medical experts don’t know the specific cause of osteochondritis dissecans. Genetics may play a role. Some think that a lack of blood flow and oxygen to a joint leads to this condition. Others agree that repetitive stress to a joint (for example, repeated stress fractures) may result in osteochondritis dissecans.
Because the cause of osteochondritis dissecans isn’t known, there’s no clear way to prevent it. Only 15 to 29 people out of 100,000 get osteochondritis dissecans. The condition is most common in children and adolescents who play regular, highly competitive sports. It can affect adults if they had undiagnosed or untreated osteochondritis dissecans as a child.