The syndesmosis is the articulation of the tibia and the fibula just proximal to the tibiotalar joint. It is a joint with articular cartilage and is stabilized by the syndesmotic ligaments [anterior-inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), and interosseous ligament].

The incisura fibularis tibiae is the lateral cavity of the tibia with which the fibula articulates. This anatomic feature of the tibia can differ fairly significantly from the almost C shape in the axial plane to a much flatter shape.

The mortise is composed of the articulation between the tibia and fibula superiorly and the talus inferiorly.

Much of the stability of the ankle mortise in stance comes from the bony conformity. A host of ligaments provide static restrictions to various ankle and hindfoot motions, while tendons can provide a dynamic component to this stability.

The capsule of the ankle joint is confluent with ligamentous structures laterally, posteriorly, and medially, while extending a few centimeters proximal to the plafond anteriorly. The role of the ankle capsule in ankle function is currently unclear.

The articular cartilage of the ankle is fundamentally different from that of the knee in ways that may relatively protect the ankle.

The fibula extends distal to the tibia and should form a curve, whereby the distal fibula is confluent with the lateral process of the talus.

The central goal of treatment of an ankle fracture is the restoration of full function. Treatment should be tailored to maximize function and minimize the risk of PTA.

Whether surgery is warranted or not will depend on injury and patient factors.

If surgery is needed, then the general concepts of anatomic reduction with rigid fixation coupled with delayed weight bearing and early range of motion should generally be followed.

More specifically with regards to surgery, length and rotation of the fibula must be restored, while intraarticular fractures must be anatomically reduced.

Given the differences involved with different types of fractures, the discussion of treatment will be made for each individual type of fracture.

SAD fractures are coronal plane injuries that are essentially the same mechanism as an ankle sprain. With type 1 injuries, there is a Weber A fibula fracture, while type 2 fractures are characterized by impaction of the talus into the medial shoulder of the plafond, creating a characteristic vertical medial malleolus fracture.

Marginal impaction can occur in the medial plafond; its presence should be actively sought and assessed with a CT scan if unclear on plain films.

SAD 1 fractures are essentially ankle sprain-equivalent injuries and rarely require operative treatment. If operative treatment is necessary, a single longitudinal screw is usually sufficient.

SAD 2 fractures will require operative treatment. A longitudinal anteromedial incision will allow access to the joint for disimpaction and anatomic reduction. Bone grafting is occasionally necessary. A medial buttress plate with subchondral lag screws provides optimal fixation.

SER fractures occur through 4 stages.

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  SER 1 fractures: In original description, this injury consisted of tear of AITFL or fracture of Chaput (insertion of AITFL on tibia) or Wagstaffe tubercle (insertion of AITFL on fibula); practically, these injuries, unless they involve large fracture fragment, likely get grouped in with ankle sprains more than fractures; surgical treatment is only rarely necessary

  
  
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  SER 2 fractures: Each stage is progressive, and so this would involve an SER 1 and an oblique fracture (Weber B) of the distal fibula; typical fracture orientation runs from anterior inferior to posterior superior

  
  
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  SER 3 fractures: SER 2 with either PITFL tear or posterior malleolar fracture

  
  
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  SER 4 fractures: SER 3 with either deltoid ligament tear or medial malleolar fracture

Generally speaking, SER 4 fractures are treated operatively. It can often be difficult to clearly diagnose SER 2 vs. SER 4 fractures on nonstress radiographs, especially when there is no medial fracture.

External rotation stress radiographs can help to differentiate SER 2 from SER 4 fractures. Opening of the medial clear space generally signifies injury to the deltoid ligament, although there has been debate about what degree of opening is truly indicative of injury, and different surgeons have different thoughts. The longitudinal data that would allow for a better understanding of how best to treat these injuries is currently lacking.

Some authors view opening of the medial clear space in a binary fashion, whereby a differentiation is made between those that nearly dislocate vs. those that widen a couple millimeters. Widening of a few millimeters is ultimately of unclear significance, especially given the inherent error in measurement, the lack of a consistently superior mode of measurement, and the inherent difficulty of standardizing how hard one should pull. Further, early results suggest that many of these equivocal injuries will stabilize under the mortise and attain stability over time, although, once again, more relevant long term data is lacking.

Like SAD fractures, PAB fractures are strictly coronal plane injuries, although the injury starts on the medial side.

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  PAB 1 fractures: Transverse medial malleolar fracture

  
  
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  PAB 2 fractures: PAB 1 + disruption of the syndesmotic ligaments with possible posterior malleolar fracture

  
  
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  PAB 3 fractures: PAB 2 + Weber C comminuted fibula fracture

These fractures will often need surgery, as they will be displaced; syndesmotic disruption is common with these injuries.

Attaining appropriate length and rotation of the fibula can be challenging in these fibula fractures, especially with significant comminution.

Talar dome fractures can occur from shear stresses associated with the fracture.

Like SER fractures, PER fractures occur through 4 stages.

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  PER 1 fractures: Transverse medial malleolar fracture

  
  
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  PER 2 fractures: PER 1 + AITFL tear

  
  
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  PER 3 fractures: PER 2 + spiral fibular fracture (Weber C), anterior superior to posterior inferior

  
  
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  PER 4 fractures: PER 3 + PITFL tear or posterior malleolar fracture

As before, PER injuries are often associated with syndesmotic disruption.

Operative treatment is the norm for these injuries.

Posterior pilon fractures can encompass any of the above if the injury has an axial component.

You will often see some marginal impaction of the fracture with an impacted fragment anterior to the posterior malleolar fracture.

They may necessitate a posterolateral approach to the ankle, utilizing the interval between the peroneal tendons laterally and the flexor hallucis longus medially. Care must be taken to protect the sural nerve given its proximity to the approach.

While traditional thinking on posterior malleolar fractures focused on the size of the fractured fragment as the main feature influencing surgical decision making, surgeons now also take into account the presence of any marginal impaction and the effect of PITFL restoration on syndesmotic stability.

Good results have been achieved with these injuries, although these injuries must be recognized and treated appropriately.

Disruption of the syndesmosis often represents a diagnostic challenge. In the setting of an ankle fracture, the fibula is typically stabilized prior to assessing syndesmotic instability.

The Cotton test is the most widely known test of syndesmotic instability, whereby the fibula is clamped, and any widening is sought in the coronal plane. A more sensitive measure of syndesmotic instability, however, may be seen in the sagittal plane where excess sagittal motion of the fibula relative to the tibia may indicate syndesmotic instability.

Other authors have suggested using arthroscopic evaluation to assess for syndesmotic instability.

An anatomic reduction of the syndesmosis is likely best achieved with an open reduction in order to directly place the fibula into the incisura. Further, some authors have noted that the quality of syndesmosis reduction correlates directly with outcome.

Syndesmotic reduction can be maintained with either syndesmotic screws or suture button devices. Some evidence suggests that suture button devices may be more forgiving in terms of reduction and may allow for better results in terms of functional outcome, quality of life, and pain.

Outpatient management of ankle fractures may be cheaper and associated with less medical morbidity postoperatively. A delay in timing between injury and surgery does not appear to adversely affect outcome.

Pain management focuses on minimizing the use of opioid medications by providing multimodal analgesia.

Deep vein thrombosis (DVT) prophylaxis appears unnecessary after ankle fracture given the low incidence of DVT and pulmonary embolism after ankle fracture. DVT prophylaxis should be considered in patients that are high risk.

Weight-bearing recommendations after ankle open reduction and internal fixation (ORIF) surgery have historically been a source of significant variability, often based more on tradition than any objective criteria.

Recent evidence has shown no difference in wound complications, infection, loss of reduction, or hardware failure with 2 weeks of non-weight bearing (NWB) as opposed to 6 weeks of NWB after ORIF of multiple types of ankle fractures.