Ottawa ankle rules

In medicine, the Ottawa ankle rules are a set of guidelines for doctors to aid them in deciding 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 X-rayed. However only about 15% of X-rays were positive for fracture, other patients had sprains or other injuries. As a result many unnecessary X-rays were taken, which was costly, time consuming and a possible health risk.

The Ottawa ankle rules
X-rays are 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.

The Ottawa foot rules are for assessing whether a foot X-ray series is indicated. It states that they are 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.

Utility of the Ottawa rules
The rules have been found to have a very low rate of false negatives. Evidence in systematic reviews supports the Ottawa ankle rules as an accurate instrument for excluding fractures of the ankle and mid-foot. The instrument has a sensitivity of almost 100% and a modest specificity, and its use should reduce the number of unnecessary radiographs by 30-40%.

Among the studies in the original review their research reported that the test was 100% sensitive and reduced the number of ankle X-rays by about 35%. A second trial with a larger number of patients confirmed these findings. Subsequently, a multi-centre study was done that explored the feasibility of implementing the rules on a wider scale. Unfortunately, teaching the rules to patients does not appear to help reduce presentation to hospital.

Generalization to other joints
The original rules were developed for ankle and foot injuries only, but similar guidelines have been developed for other injuries such as the Ottawa Knee Rule.

History
The Ottawa ankle rules were developed by a team of doctors in the Urgent Care department of the Ottawa Hospital in Ottawa, Canada. Since the rules were formulated in Ottawa they were dubbed the Ottawa ankle rules by its creators a few years after their development, a title that has stuck. In this respect, the naming of the rules is similar to those of the Bristol stool scale or the Glasgow Coma Scale (GCS), which also take their names from the cities in which they were created.