Fallen fragment sign on X-ray is seen in -
Fallen fragment sign and hinged fragment sign are seen in simple bone cyst. Fallen fragment sign refers the settlement of fractured fragment in dependent position Hinged fragment sign (aka Trap door sign) refers to non separation of fractured fragment from the adjacent coex.
Simple bone cyst
Aneurysmal bone cyst
GCT
Fibrous dysplasia
Skeletal system