The Monteggia fracture is a fracture of the ulna that affects the joint with the radius.
More precisely, it is a fracture of the proximal third of the ulna with dislocation of the head of the radius.
It is named after Giovanni Battista Monteggia.
There are four types (depending upon displacement of the radial head):
I – Extension type (60%) – ulna shaft angulates anteriorly (extends) and radial head dislocates anteriorly.
II – Flexion type (15%) – ulna shaft angulates posteriorly (flexes) and radial head dislocates posteriorly.
III – Lateral type (20%) – ulna shaft angulates laterally (bent to outside) and radial head dislocates to the side.
IV – Combined type (5%) – ulna shaft and radial shaft are both fractured and radial head is dislocated, typically anteriorly.
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