AO North America

The Comprehensive Classification of Fractures of Long Bones

13-Humerus Distal

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

13a

A1 Extra-articular fracture, apophyseal avulsion
.1 lateral epicondyle
.2 medial epicondyle, non incarcerated
.3 medial epicondyle, incarcerated

A2 Extra-articular fracture, metaphyseal simple
.1 oblique downwards and inwards
.2 oblique downwards and outwards
.3 transverse

A3 Extra-articular fracture, metaphyseal multifragmentary
.1 with an intact wedge
.2 with a fragmented wedge
.3 complex

13b

B1 Partial articular fracture, lateral sagittal
.1 capitellum
.2 transtrochlear simple
.3 transtrochlear multifragmentary

B2 Partial articular fracture, medial sagittal
.1 transtrochlear simple, through the medial side (Milch I)
.2 transtrochlear simple, through the groove
.3 transtrochlear multifragmentary

B3 Partial articular fracture, frontal
.1 capitellum
.2 trochlea
.3 capitellum and trochlea

13c

C1 Complete articular fracture, articular simple, metaphyseal simple
.1 with slight displacement
.2 with marked displacement
.3 T-shaped epiphyseal

C2 Complete articular fracture, articular simple, metaphyseal multifragmentary
.1 with an intact wedge
.2 with a fragmented wedge
.3 complex

C3 Complete articular fracture, multifragmentary
.1 metaphyseal simple
.2 metaphyseal wedge
.3 metaphyseal complex

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