Subclasses of injury are not always injuries

[nklsbckmnn]

I see a problem with injuries. Injury is defined as "Damage inflicted on the body as the direct or indirect result of an external force, with or without disruption of structural continuity." "Bone fracture" has injury as its only superclass. Where to we put fractures without significant trauma though? External forces in a narrower sense do not seem to be necessary for bone fractures. The only "external force" identifiable here might be gravity and that plays a role in all kinds of diseases. External forces in a super broad sense are necessary for all kinds of diseases and can't serve as a logically sufficient criterion in a definition for injuries. In that case we need additional necessary criteria. On both readings, bone fractures should not be restricted to injuries.