Familial osteochondritis dissecans is a condition that affects the joints and is associated with abnormal cartilage. Cartilage is a tough but flexible tissue that covers the ends of the bones at joints and is also part of the developing skeleton. A characteristic feature of familial osteochondritis dissecans is areas of bone damage (lesions) caused by detachment of cartilage and a piece of the underlying bone from the end of the bone at a joint. People with this condition develop multiple lesions that affect several joints, primarily the knees, elbows, hips, and ankles. The lesions cause stiffness, pain, and swelling in the joint. Often, the affected joint feels like it catches or locks during movement. Other characteristic features of familial osteochondritis dissecans include short stature and development of a joint disorder called osteoarthritis at an early age. Osteoarthritis is characterized by the breakdown of joint cartilage and the underlying bone. It causes pain and stiffness and restricts the movement of joints.

A similar condition called sporadic osteochondritis dissecans is associated with a single lesion in one joint, most often the knee. These cases may be caused by injury to or repetitive use of the joint (often sports-related). Some people with sporadic osteochondritis dissecans develop osteoarthritis in the affected joint, especially if the lesion occurs later in life after the bone has stopped growing. Short stature is not associated with this form of the condition.

The signs and symptoms of osteochondritis dissecans vary from person to person. If the piece of cartilage and bone remain close to where they detached, they may not cause any symptoms. However, affected people may experience the following if the cartilage and bone travel into the joint space:

• Pain, swelling and/or tenderness
• Joint popping
• Joint weakness
• Decreased range of motion

Although osteochondritis dissecans can develop in any joint of the body, the knee, ankle and elbow are most commonly affected. Most people only develop the condition in a single joint.

A diagnosis of osteochondritis dissecans is usually suspected based on the presence of characteristic signs and symptoms. Additional testing can then be ordered to confirm the diagnosis. These test may include x-rays, magnetic resonance imaging (MRI) and/or computed tomography (CT scan).