The Bado Classification of Monteggia Fractures.

Type I: anterior dislocation of the radial head with associated anteriorly angulated fracture of the ulna shaft. Type II: posterior dislocation of the radial head with a posteriorly angulated fracture of the ulna. Type III: lateral or anterolateral dislocation of the radial head with a fracture of the ulnar metaphysic. Type IV: anterior dislocation of the radial head with a fracture of the radius and ulna.

(Reprinted with permission from BadoJL. The Monteggia lesion. Clin Orthop Relat Res1967;50:70–86.)