Investigation of ankle injury (summary)

Ankle injury is a ubiquitous problem seen commonly in all minor injuries units and Emergency departments. Presentation may be the result of a relatively minor trip, or following a more significant traumatic precipitant.

Assessment

Following ankle trauma, the two main differential diagnoses are of a ligamentous injury (ankle sprain) and a fracture. The decision about whether an ankle x-ray is needed can be made using the Ottawa ankle rules.

Ottawa ankle/foot rules

An ankle radiograph is only required if:

• bony tenderness along the posterior border of the lateral malleolus, or
• bony tenderness along the posterior border of the medial malleolus, or
• inability to weightbear at the time of injury AND assessment

A foot radiograph is only required if:

• bony tenderness of the base of the 5th metatarsal, or
• bony tenderness of the navicular, or
• inability to weightbear at the time of injury AND assessment

Investigation

If an x-ray is required based on clinical assessment, then either an ankle or foot x-ray will be required to determine whether there is a fracture. It is relatively rare that both a ankle and foot x-rays are needed.

Distal fibula fractures are important injuries because depending on the involvement of the syndesmosis, the treatment strategy varies significantly. The Weber classification aids in the determination of treatment strategy and prognosis. 

Common pathology

• distal fibula fracture
  • Weber classification
• base of 5th metatarsal fracture
• ankle sprain (ligamentous injury)
  • lateral collateral ligament - inversion
  • deltoid ligament - eversion