The ulnar fracture may be segmental or multifragmentary, the radius may be intact or injured with a simple fracture. In the latter case, the fractures are classified independently according to the morphology of each fracture.
Multifragmentary forearm fractures are usually the result of higher energy trauma, such as motor vehicle accidents, falls from heights, high velocity gunshot injuries, etc.
Segmental fracture of the ulna
Segmental ulnar fractures are classified by AO/OTA as 2U2C2.
They may be associated with a dislocation of the radial head from the radiocapitellar joint; the proximal radioulnar joint is also disrupted (Monteggia). This is indicated by the qualifier (m), so if the fracture illustrated is associated with a proximal dislocation, it would be a 2U2C2(m).
Segmental ulnar fracture, with associated radial fracture