From the Guidelines
The Ottawa ankle rules are clinical decision guidelines that state ankle X-rays are only required if there is an inability to bear weight immediately after the injury, point tenderness over the medial malleolus, the posterior edge or inferior tip of the lateral malleolus, talus, or calcaneus, or an inability to ambulate for 4 steps in the emergency department, as validated by recent studies 1. These rules apply to patients who are alert, over 5 years of age, and have no other distracting injuries or conditions that would impair their ability to report pain accurately. The guidelines are used to determine when X-rays are necessary for patients with ankle injuries, with the goal of reducing unnecessary radiography while maintaining high sensitivity for detecting clinically significant fractures. Key points of the Ottawa ankle rules include:
- Inability to bear weight immediately after the injury
- Point tenderness over specific areas, including the medial malleolus, the posterior edge or inferior tip of the lateral malleolus, talus, or calcaneus
- Inability to ambulate for 4 steps in the emergency department Recent meta-analyses have confirmed the effectiveness and utility of the Ottawa ankle rules, with sensitivity of 92% to 100% and specificity of 16% to 51% in excluding fractures in the acute ankle setting 1. The use of these rules can help reduce unnecessary radiographs and costs, and improve clinical outcomes, with some studies showing a reduction in emergency room patient stay by up to 20 minutes 1.
From the Research
Ottawa Ankle Rules
The Ottawa Ankle Rules (OAR) are a tool used by physicians to determine whether an x-ray is necessary after an ankle or midfoot injury 2. The rules state that an ankle x-ray is required if there is:
- Bone tenderness along the distal six centimeters of the posterior part of the medial or lateral malleolus
- Inability to bear weight immediately after the accident and in the emergency department
For midfoot injuries, an x-ray is required if there is:
- Bone tenderness at the base of the 5th metatarsal or the navicular bone
- Inability to bear weight immediately after the accident and in the emergency department 2
Application of the Ottawa Ankle Rules
The OAR can be applied by physicians and non-physician providers to minimize unnecessary radiographs in ankle and foot injuries 3. The rules have been shown to be accurate in ruling out fractures after an ankle sprain, with sensitivity ranging from 92-100% and specificity ranging from 16-51% 4.
Refining the Ottawa Ankle Rules
Some studies suggest refining the OAR to include an age criterion, as the rules may be less specific in geriatric patients 5. For example, one study proposed that patients aged 65 years or older with ankle pain should undergo imaging studies, regardless of other criteria 5.
Benefits of the Ottawa Ankle Rules
The use of the OAR can reduce the number of x-rays ordered, potentially saving costs and time 2. The rules can also help prevent patients from unnecessary radiation exposure 6. Key points to consider when applying the OAR include:
- The rules are a reliable tool to exclude fractures in children over 5 years of age when applied by physicians 3
- Non-physician providers can accurately apply the OAR, but may require additional training and practice to improve inter-observer reliability 3
- The OAR can be used in conjunction with other tools, such as the Bernese ankle rules, vibrating tuning fork test, and ultrasound, to decrease the need for radiographs 4