Diagnosis

Infrasyndesmotic lesion, isolated (AO/OTA 44A1) 

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Infrasyndesmotic fractures (AO/OTA Type 44A) occur with the foot supinated and an adduction force applied to the talus, causing the lateral structures to fail in tension.

Isolated lateral side injuries, with the medial side intact, are classified as AO/OTA group 44A1. These correspond to supination-adduction fractures stage I in the Lauge-Hansen classification.

Complete radiological evaluation (AP, lateral and AP with internal rotation) is crucial for correct classification and decision making.

Options
1. Rupture of the lateral collateral ligaments (AO/OTA 44A1.1) 
2. Avulsion of the tip of the lateral malleolus (AO/OTA 44A1.2) 
3. Transverse fracture of the lateral malleolus (AO/OTA 44A1.3) 

1. Rupture of the lateral collateral ligaments (AO/OTA 44A1.1) 

Rupture of the lateral collateral ligaments (AO/OTA 44A1.1)

Rupture of the lateral collateral ligaments (AO/OTA 44A1.1)

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

Radiograph taken from Orozco R et al, (1998) Atlas of Internal Fixation. Used with kind permission.

2. Avulsion of the tip of the lateral malleolus (AO/OTA 44A1.2) 

Avulsion of the tip of the lateral malleolus (AO/OTA 44A1.2)

Avulsion of the tip of the lateral malleolus (AO/OTA 44A1.2)

If the lateral injury involves an avulsion of the tip of the lateral malleolus this is classified as an AO/OTA 44A1.2 fracture.

Radiograph taken from Orozco R et al, (1998) Atlas of Internal Fixation. Used with kind permission.

3. Transverse fracture of the lateral malleolus (AO/OTA 44A1.3) 

Transverse fracture of the lateral malleolus (AO/OTA 44A1.3)

Transverse fracture of the lateral malleolus (AO/OTA 44A1.3)

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.

Radiograph taken from Orozco R et al, (1998) Atlas of Internal Fixation. Used with kind permission.