What two features support this theory?
The segment of clavicle which is fractured appears lucent with irregular margins and a wide zone of transition. In addition periosteal reaction is seen superiorly, which is against this being and acute injury.
Minimally displaced fracture through the distal third of the clavicle, at or just lateral to the coracoclavicular ligaments. The underlying bone appears abnormal and lucent, with a wide zone of transition and periosteal reaction is already visible.