Aneurysmal bone cyst arising after anterior cruciate ligament rupture

An aneurysmal bone cyst, a condition first described in 1942, is a relatively rare benign tumor. Approximately 1% of all primary bone tumors are aneurysmal cysts. Diagnosis is typically made in a patient's first or second decade and rarely follows trauma. This is the first reported case of an aneurysmal bone cyst arising after rupture of the anterior cruciate ligament.