Malleoli

If the lateral lesion is a rupture or avulsion of the lateral collateral ligaments, (ligamentum calcaneofibulare and ligamentum talofibulare anterius / posterius) it is classified as an AO/OTA 44A1.1 or AO/OTA 44A1.2 injury.

When the lateral injury is a transverse fracture of the lateral malleolus below the syndesmotic ligament this classified as an AO/OTA 44A1.3 fracture.

If the lateral malleolus is intact, and the lateral injury involves a rupture of the lateral collateral ligaments (the calcaneo-fibular ligament and the anterior and posterior talo-fibular ligaments), with a medial malleolar fracture (oblique or vertical), this is classified as an AO/OTA 44A2.1 fracture.

If the lateral injury involves an avulsion fracture of the tip or a transverse fracture of the lateral malleolus, with a medial malleolar fracture (oblique or vertical), this is classified as an AO/OTA 44A2.2 or an  AO/OTA 44A2.3  fracture.

If the lateral malleolus is intact, and the lateral injury involves a rupture of the lateral collateral ligaments (the calcaneo-fibular ligament and the anterior and posterior talo-fibular ligaments), with a posteromedial malleolar fracture, this is classified as an AO/OTA 44A3.1 fracture.

If the lateral injury involves an avulsion fracture of the tip, or a transverse fracture of the lateral malleolus,  with a posteromedial malleolar fracture, this is classified as an AO/OTA 44A3.2 or AO/OTA 44A3.3 fracture.

If there is a simple fracture at the level of the syndesmotic ligaments, either undisplaced, or minimally displaced it is classified as an AO/OTA 44B1.1 or B1.2 fracture.

The stress begins at the anterior syndesmotic ligament and results in a ligamentous rupture or in an avulsion fracture of the anterior syndesmotic ligament's fibular or tibial insertion (Lauge-Hansen, SE stage I). Further stress due to continued external rotation of the talus leads to the fibular fracture (Lauge-Hansen, SE stage II).

When there is a simple, displaced, oblique fracture at the level of the syndesmotic ligaments, associated with a rupture of the medial collateral ligament, this is classified as an AO/OTA 44B2.1 fracture.

When there is a simple, displaced, oblique fracture at the level of the syndesmotic ligaments, associated with a fracture of the medial malleolus, this is classified as an AO/OTA 44B2.2 fracture.

When there is a multifragmentary fracture at the level of the syndesmotic ligaments, this is classified as an AO/OTA 44B2.3 fracture.

If there is a simple, oblique fibular fracture at the level of the syndesmotic ligaments, associated with a posterior malleolar fracture, and the injury on the medial side is a rupture of the deltoid ligament, this is classified as an AO/OTA 44B3.1 fracture.

If there is a simple, oblique fibular fracture at the level of the syndesmotic ligaments, associated with a posterior malleolar fracture, and a medial malleolar fracture, this is classified as an AO/OTA 44B3.2 fracture.

If there is a multifragmentary fibular fracture at the level of the syndesmotic ligaments, associated with a posterior malleolar fracture, this is classified as an AO/OTA 44B3.3 fracture.