AO/OTA classification of malleolar fractures

The AO/OTA classification of malleolar segment fractures is one of the most frequently used systems for classifying malleolar fractures. It takes the Danis-Weber classification into account and can be correlated to the Lauge-Hansen classification.

Malleolar fractures are divided into three groups subject to the severity and complexity of the respective injury ^{1, 2}:

• type A: infrasyndesmotic fibular injury

  • A1: isolated lateral malleolar injury

    • corresponds to supination-adduction injury – Lauge-Hansen stage I

    • A1.1 lateral collateral ligament injury

    • A1.2 lateral malleolus tip avulsion

    • A1.3 isolated transverse infrasyndesmotic lateral malleolar fracture

  • A2: infrasyndesmotic fibular injury and medial malleolar fracture

    • A2.1 lateral collateral ligament injury and medial malleolar fracture

    • corresponds to supination-adduction injury – Lauge-Hansen stage II

    • A2.2 lateral malleolus tip avulsion and medial malleolar fracture

    • A2.3 transverse infrasyndesmotic lateral malleolar fracture

  • A3: infrasyndesmotic fibular injury with a posteromedial fracture

    • no injury pattern in Lauge-Hansen classification

    • A3.1 infrasyndesmotic fibular injury and posteromedial fracture

    • A3.2 lateral malleolus tip avulsion and posteromedial fracture

    • A3.3 transverse infrasyndesmotic and posteromedial fracture

• type B: transsyndesmotic fibular fracture

  • B1: isolated transsyndesmotic fibular fracture

    • corresponds to supination-eversion injury – Lauge-Hansen stage I-II

    • B1.1 simple transsyndesmotic lateral malleolar fracture

    • B1.2 transsyndesmotic lateral malleolar fracture with anterior syndesmotic rupture

    • B1.3 wedge or multifragmentary transsyndesmotic lateral malleolar fracture

  • B2: transsyndesmotic fibular fracture with medial injury

    • corresponds to pronation-abduction injury – Lauge-Hansen stage I-III

    • B2.1 anterior syndesmotic rupture and deltoid ligament rupture

    • B2.2 anterior syndesmotic rupture and medial malleolar fracture

    • B2.3 wedge or multifragmentary transsyndesmotic fracture and medial injury

  • B3: transsyndesmotic fibular fracture with medial injury and posterolateral rim (Volkmann) fracture

    • B3.1 simple transsyndesmotic fracture with deltoid rupture and Volkmann fracture

    • B3.2 simple transsyndesmotic and medial malleolar fractures and Volkmann fracture

    • B3.3 wedge or multifragmentary transsyndesmotic, medial and Volkmann fracture

  • all but type B1.1 transsyndesmotic fibular fractures can be associated with Tillaux-Chaput tubercle fractures or Wagstaffe-Le Fort avulsions

• type C: suprasyndesmotic injury

  • C1: simple suprasyndesmotic fibular diaphyseal fracture with one of the following:

    • correspond to pronation-eversion injury – Lauge-Hansen stage I-IV

    • C1.1 rupture of the deltoid ligament

    • C1.2 fracture of the medial malleolus

    • C1.3 medial malleolar and posterior rim (Volkmann) fracture

  • C2: wedge or multifragmentary suprasyndesmotic fibular diaphyseal fracture with the following:

    • C2.1 rupture of the deltoid ligament

    • C2.2 fracture of the medial malleolus

    • C2.3 medial malleolar and posterior malleolar (Volkmann) fracture

    • C1 and C2 lesions can be additionally subcategorised regarding syndesmotic stability

    • correspond to pronation-eversion injury – Lauge-Hansen stage I-IV

  • C3: proximal suprasyndesmotic injury with the following:

    • C3.1 medial injury: deltoid ligament rupture or medial malleolar fracture

    • C3.2 fibular shortening and medial injury

    • C3.3 medial injury and posterior malleolar (Volkmann) fracture

    • C3 fractures can be additionally subdivided concerning proximal fibular injury (fracture/tibiofibular joint dislocation) and medial injury (deltoid ligament rupture/malleolar fracture)

If isolated medial malleolar fractures and isolated posterior malleolar or Volkmann fractures are not associated with a lateral malleolar injury or a fibular fracture they are classified and coded as partial articular distal tibial end segment fractures ¹.

See also

• AO/OTA classification of distal tibial fractures

• Weber classification of ankle fractures

• Lauge-Hansen classification

• Volkmann fracture