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Revised AO/OTA classification (Jan 2018)


A revision of the AO/OTA Fracture and Dislocation Classification was published in the January 2018 issue of the Journal of Orthopaedic Trauma (Compendium and support material). This module is organized according to the 2007 version. Please read through its revised classification (below) before returning to the AO Surgery Reference.

33A1 Extraarticular, avulsion fracture

33A1.1 Lateral epicondyle fracture

33A1.2 Medial epicondyle fracture

33A2 Extraarticular, simple fracture

33A2.1 Spiral fracture

33A2.2 Oblique fracture

33A2.3 Transverse fracture

33A3 Extraarticular, wedge or multifragmentary fracture

33A3.1* Intact wedge fracture

f – Lateral
h - Medial

33A3.2* Fragmentary wedge fracture

f – Lateral
h - Medial

33A3.3 Multifragmentary fracture

33B1 Partial articular, lateral condyle, sagittal fracture

33B1.1 Simple through the notch

33B1.2 Simple through the load bearing surface

33B1.3 Fragmentary fracture

33B2 Partial articular, medial condyle, sagittal fracture

33B2.1 Simple through the notch

33B2.2 Simple through the load bearing surface

33B2.3 Fragmentary fracture

33B3 Partial articular, frontal/coronal fracture

33B3.1 Anterior and lateral flake fracture

33B3.2* Posterior unicondylar fracture (Hoffa)

f - Lateral
h - Medial

33B3.3 Posterior bicondylar fracture

(bilateral Hoffa)

33C1 Complete, simple articular, simple metaphyseal fracture

33C1.1 Above transcondylar axis

33C1.3 Through or below the transcondylar axis

33C2 Complete, simple articular, wedge or multifragmentary metaphyseal fracture

33C2.1* Intact wedge metaphyseal fracture

f - Lateral
h - Medial

33C2.2* Fragmentary wedge metaphyseal fracture

f - Lateral
h - Medial

33C2.3 Multifragmentary metaphyseal fracture

33C3 Complete, multifragmentary articular, simple, wedge or multifragmentary metaphyseal fracture

33C3.1 Simple metaphyseal fracture


33C3.2* Wedge metaphyseal fracture

f - Lateral
h - Medial
s - Intact
l - Fragmentary

33C3.3 Multifragmentary metaphyseal fracture

Executive Editor: Chris Colton

Authors: Florian Gebhard, Phil Kregor, Chris Oliver

Additional credits

Distal femur



Fractures of the distal femur may be extraarticular or have an intraarticular component. Mismanagement of any of these fractures can result in abnormalities of alignment of the load-bearing axis of the lower limb and/or rotational deformities. These can have profound biomechanical consequences.

Additionally, the intraarticular fractures can result in joint irregularities leading to degenerative joint disease.

Treatment is based on sound bone healing with full restoration of the biomechanical axes and of the joint surfaces.

Accurate diagnosis and categorization of the injury anatomy leads to a full understanding of the repertoire of treatment methods, wise surgical decision making and improved outcomes.

Further comments regarding distal femoral fractures.


Evidence summary

Decision support

Additional material

Further reading

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v1.0 2008-12-03