<prompt> Fallen fragment sign is a feature of ?Simple bone cystAneurysmal bone cystGiant cell tumorFibrous dysplasia  <response>: Ans. is a i.e., Simple bone Simple bone cyst SoliteryUnicameral bone cyst Simple bone cyst occurs before the age of 20 years The most common site is proximal humerus 50followed by Proximal femur 25-30. Radiological features are : - Concentric Metaphyseal Expansile lucent lytic Well defined border with sclerotic margin Fallen Fragment sign : - Coical fragment of pathological fracture settles in the most dependent poion. Hinged fragment sign : - Sometimes fractured fragment does not separate from adjacent coex. 