Monteggia fracture-dislocations are classified by the Bado system. Bado type I injuries are characterized by a proximal ulnar fracture with anterior dislocation of the radial head. This is due to a forceful pronation injury of the forearm and is the most common type. Bado type II injuries are "reversed" Monteggia fracture-dislocation injuries. Here, there is posterior angulation of the ulnar fracture site and posterior dislocation of the radial head. Bade type III and IV injuries are rare.

A	AP radiograph of the elbow. This shows a comminuted fracture of the proximal ulna.
B	Lateral radiograph of the elbow. This demonstrates posterior dislocation of the radial head, a "reversed" Monteggia injury (Bado type II).

Links to online textbooks:

• Wheeless' Orthopedics: discussion of Monteggia fracture-dislocations

Links to online cases:

• Uhrad.com
• University of Delaware
• American Family Physician

References:

• Ring D, Jupiter JB, Simpson NS: Monteggia fractures in adults J Bone Joint Surg Am. 1998 Dec;80(12):1733-44.           [See related articles]
• Kay RM, Skaggs DL: The pediatric Monteggia fracture Am J Orthop. 1998 Sep;27(9):606-9.           [See related articles]