Syndesmotic ankle fractures

Injuries to the distal tibiofibular syndesmosis may present as ligament ruptures or bony avulsions. Both are equally important to overall ankle stability and are considered equivalent in the wake of ankle fractures. Syndesmotic ankle fractures and avulsions occur frequently at the anterior tibial tubercle (Tillaux-Chaput fracture – anterior malleolus, AM), anterior fibular tubercle (Wagstaffe-Le Fort fracture) or the posterior tibial tubercle (Earle’s or Volkmann’s triangle – posterior malleolus, PM). Overlooked, avulsed fragments may interfere with anatomic reduction of the distal fibula into the tibial incisura which is of prognostic relevance.

With suspected injury to the anterior or posterior tibial rim, the indication to perform computed tomography (CT) imaging should be made generously. With increased understanding of the three-dimensional pathoanatomy, fragment size of the avulsed posterior (and anterior) fragments is not the sole criterion for fixation anymore. Individualized treatment recommendations are guided by CT-based classifications of PM and AM fractures. These include criteria like displacement, joint impaction, the presence of intercalary fragments and loose bodies.

Anatomic reduction and internal fixation of displaced PM and AM fractures aims at recreation of the tibial incisura thus facilitating fibular reduction and restoration of the joint surface. Direct fixation of syndesmotic avulsions allows bone-to-bone stabilization of the syndesmosis rather than indirect stabilization with a syndesmotic screw or flexible implant. Direct fixation of PM fragments reportedly allows for higher quality of reduction and a more stable fixation than indirect reduction and fixation with a-p screws which in turn translates in superior outcome. A similar effect can be assumed for displaced AM fractures and needs to be confirmed in future studies.