True regarding Monteggia fracture is:

: Upper ulnar fracture & dislocated radial head 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. Bado type III and IV are rare injuries. REF : Maheshwari book of ohopedics 6th Ed.