Osteochondritis dissecans: a diagnosis not to miss.

Osteochondritis dissecans is the most common cause of a loose body in the joint space in adolescent patients. Because clinical findings are often subtle, diagnosis requires a high index of suspicion. Limited range of motion may be the only notable clinical sign. The diagnosis is made by radiographic examination, and magnetic resonance imaging has a key role in determining the stability of the lesion. Conservative management is the mainstay of treatment for stable lesions. While the majority of patients respond to conservative treatment, those with unstable lesions require arthroscopic management.