AO North America

The Comprehensive Classification of Fractures of Long Bones

21-Radius/Ulna Proximal

The subgroups represent a variation within the group and the one illustrated is indicated with red in the text.

extra articular fractures

A1 Extra-articular fracture, radius intact
.1 avulsion of the triceps insertion from the olecranon
.2 metaphyseal simple
.3 with a glenohumeral dislocation

A2 Extra-articular fracture, of the radius, ulna intact
.1 avulsion of the bicipital tuberosity of the radius
.2 neck simple
.3 neck multifragmentary

A3 Extra-articular fracture of both bones
.1 simple of both bones
.2 multifragmentary of one bone and simple of the other
.3 multifragmentary of both bones

21-Radius/Ulna Proximal

B1 Articular fracture, of the ulna, radius intact
.1 unifocal
.2 bifocal simple
.3 bifocal multifragmentary

B2 Articular fracture, of the radius, ulna intact
.1 simple
.2 multifragmentary without depression
.3 multifragmentary with depression

B3 Articular fracture, of the one bone, with extra-articular fracture of the other
.1 ulna, articular simple
.2 radius, articular simple
.3 lesser tuberosity fractured + posterior dislocation

bone fractures

C1 Articular fracture, of both bones, simple
.1 olecranon and head of radius
.2 coronoid process and head of radius

C2 Articular fracture, of both bones, the one simple and the other multifragmentary
.1 olecranon multifragmentary, radial head simple
.2 olecranon simple, radial head multifragmentary
.3 coronoid process simple, radial head multifragmentary

C3 Articular fracture, of both bones, multifragmentary
.1 three fragments of each bone
.2 ulna, more than three fragments
.3 radius, more than three fragments