AO/OTA classification of distal humeral fractures

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The AO/OTA classification of distal humeral fractures is one of the most frequently used systems for classifying distal humeral fractures.

The AO classification divides distal humeral fractures into three groups, A, B and C with complexity and severity increasing .

  • type A: extraarticular 
    • A1: avulsion
      • A1.1 lateral epicondyle
      • A.1.2 medial epicondyle
    • A2: simple 
      • A2.2 oblique
      • A1.3 transverse
    • A3: wedge or multifragmentary
      • A3.2 intact or fragmentary wedge
      • A3.3 multifragmentary
  • type B: partial articular, the fracture is involving one part of the articular surface, yet the rest of the joint is still attached to the metaphysis and diaphysis
    • B1: lateral sagittal
      • B1.1 transtrochlear
      • B1.2 transcapitellar
      • B1.3 transtrochlear multifragmentary
    • B2: medial sagittal
      • B2.1 transtrochlear
      • B2.2 medial articular surface
      • B2.3 transtrochlear multifragmentary
    • B3: frontal/coronal 
      • B3.1 capitellum
      • B3.2 trochlea
      • B3.3 combo of capitellum and trochlea
  • type C: complete articular, the fracture is distributing the joint surface and separated from the diaphysis
    • C1: both the articular and the metaphyseal portions are simple
    • C2: simple articular with a fragmentary metaphyseal component 
    • C3: multifragmentary articular