Part of the TeachMe Series

Ankle Fracture

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Original Author(s): Brijmohan Pandya
Last updated: September 30, 2019
Revisions: 13

Original Author(s): Brijmohan Pandya
Last updated: September 30, 2019
Revisions: 13

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Introduction

The ankle is comprised of the talus bone located within the mortise; the mortise is comprised of the tibial plafond and the medial and lateral malleoli, the fibula and tibia attached by the strong fibrous syndesmosis.

An ankle fracture is a fracture of any malleolus (lateral, medial, or posterior), with or without disruption to the syndesmosis.

Ankle fractures are a common injury, more common in younger males or older females, and account for around 10% of all fractures seen in the trauma setting.

Figure 1 – The ankle is comprised of the tibia, fibula, and talus

Classification

Ankle fractures can be described anatomically, divided up into isolated medial malleolar fractures, isolated lateral malleolar fractures, bimalleolar fractures, and trimalleolar fractures.

Other classifications of ankle fractures, such as the Lauge-Hansen classification or Danis-Weber classification, are also used.

Lateral malleolus fractures are commonly classified via the Weber Classification (Fig. 2):

  • Type A = below the syndesmosis
  • Type B = at the level of the syndesmosis
  • Type C = above the level of the syndesmosis

Figure 2 – The Weber Classification of Ankle Fracture

Clinical Features

Patients will often present with ankle pain following an traumatic injury and being unable to weight bear. There may be associated deformity in cases of fracture dislocation (which require urgent reduction).

Check the neurovascular status of the affected foot and ensure that there is no evidence of an open fracture or compromise to the overlying skin. Whilst the ankle may be diffusely painful, focal tenderness will be present at the fracture site.

The Ottawa ankle rules can be a useful clinical decision aid in helping decide whether radiographic imaging is further required. Always ensure to also check for concomitant injuries.

The main differential diagnosis for an ankle fracture is an ankle sprain (see below).

Ottawa Ankle Rules

The Ottawa ankle rules are a clinical decision tool to help determine the need for diagnostic imaging for ankle or foot trauma.

In the case of an ankle fracture, ankle plain film radiographs are only required if there is any pain in the malleolar regions and features of:

  • Bone tenderness at the posterior edge or tip of the lateral malleolus, OR
  • Bone tenderness at the posterior edge or tip of the medial malleolus, OR
  • An inability to bear weight both immediately and in the emergency department for four steps

Whilst useful, they cannot be used in cases if the patient us intoxicated or uncooperative, has other distracting painful injuries, has diminished sensation in their legs, or has gross swelling.

Investigations

A plain radiograph (Fig. 3) should be obtained in all suspected cases, with both AP  (or mortise) and lateral views. Check the joint space for uniformity, ensuring no evidence of talar shift.

Most ankle fractures can be diagnosed and managed with plain radiographs, however CT imaging may be required in cases of complexity or diagnostic uncertainty.

Figure 3- Ankle fracture (Weber C) show on plain film radiograph, in AP and lateral views

Management

Initial management requires timely fracture reduction, usually performed under sedation, in attempt to realign the fracture to near-anatomical alignment. Any that have with evidence of an open fracture should be managed to accordingly.

Once reduced, the ankle should be placed in a below knee back slab, before repeating neurovascular examination and repeat post-manipulation plain film radiographs. If the reduction is not adequate, repeat reduction attempts may be required.

Conservative management will often be opted for in:

  • Non-displaced medial malleolus fractures
  • Weber A fractures or Weber B fractures without talar shift,
  • Those unfit for surgical intervention

Surgical Management

Open reduction and internal fixation (ORIF) is often required in ankle fractures to achieve stable anatomical reduction of the talus in the ankle mortise. Ankle fractures that require an ORIF include:

  • Bimalleolar or trimalleolar fracture
  • Weber C fracture or Weber B fracture with talar shift
  • Open fracture

The type of operative procedure performed depends on the specific type of ankle fracture sustained.

Figure 3 – Bimalleolar ankle fracture, before and after surgical fixation (using plate and screws)

Complications

The main complication following an ankle fracture is the risk of post-traumatic arthritis, however this is rare in cases with appropriate reduction and fixation.

Those who have undergone an ORIF have addition risk factors include surgical site infection and malunion.

Key Points

  • Ankle fractures are a common fracture type seen in trauma
  • Can be classified anatomically into isolated medial malleolar fractures, isolated lateral malleolar fractures, bimalleolar fractures, and trimalleolar fractures
  • Ensure to obtain sufficient plain film radiographs in AP and lateral views
  • Management depends on the type of fracture sustained, either conservatively or surgically

Ankle Sprain

Ankle sprains are ligamentous injuries and are the main differential for an ankle fracture. They can be classified into high ankle sprains, which are injuries to the syndesmosis, or low ankle sprains, which are injuries to the anterior tibiofibular ligament (ATFL) and the calcaneofibular ligament (CFL), the latter being much more common.

Patients present following an inversion injury on a plantarflexed ankle. There is often significant swelling and pain, with the patient potentially not being able to weight bear.

Imaging of choice is with plain film radiographs to rule out any bony injury. Nearly all can be managed conservatively with analgesia, ice, and elevation, following by early mobilisation.