Ottawa ankle rules

In medicine, the Ottawa ankle rules are a set of guidelines for clinicians to help decide if a patient with foot or ankle pain should be offered X-rays to diagnose a possible bone fracture. Before the introduction of the rules most patients with ankle injuries would have been imaged. However the vast majority of patients with unclear ankle injuries do not have bone fractures. As a result, many unnecessary X-rays were taken, which was costly, time-consuming and a slight health risk due to radiation exposure.

The Ottawa ankle rules

Ankle X-ray

Ankle X-ray is only required if:

There is any pain in the malleolar zone; and,

Any one of the following:

Bone tenderness along the distal 6 cm of the posterior edge of the tibia or tip of the medial malleolus, OR

Bone tenderness along the distal 6 cm of the posterior edge of the fibula or tip of the lateral malleolus, OR

An inability to bear weight both immediately and in the emergency department for four steps.

Foot X-ray series

Additionally, the Ottawa ankle rules indicate whether a foot X-ray series is required. It states that it is indicated if:

There is any pain in the midfoot zone; and,

Any one of the following:

Bone tenderness at the base of the fifth metatarsal (for foot injuries), OR

Bone tenderness at the navicular bone (for foot injuries), OR

An inability to bear weight both immediately and in the emergency department for four steps.

Certain groups are excluded, in particular pregnant women, and those with diminished ability to follow the test (for example due to head injury or intoxication). Several studies strongly support the use of the Ottawa Ankle Rules in children over 6 (98.5% sensitivity); however, their usefulness in younger children has not yet been thoroughly examined.

Usefulness

The rules have been found to have a very high sensitivity, moderate specificity, and therefore a very low rate of false negatives.