The Ottawa ankle rules exclude a fracture after an ankle injury with 97.6% sensitivity: being unable to walk four steps or having bone tenderness at specific points means an X-ray
Key Findings
The rule: an ankle X-ray is indicated if the person could not walk four steps (immediately after the injury or at assessment), or has localised tenderness at the posterior edge or tip of either malleolus. A foot X-ray is indicated with the same walking criterion or tenderness at the navicular or the base of the fifth metatarsal.
Pooled sensitivity 97.6% (96.4–98.9); median specificity 31.5%.
With a negative rule the probability of a fracture was below 1.4% at a 15% fracture prevalence.
Use of the rule should reduce unnecessary radiographs by 30–40%.
Practical Application
After any ankle sprain ask two things before training advice: could you walk four steps, and does pressing on the bone hurt — at the back edge or tip of either ankle bone, on the navicular (inner midfoot), or at the base of the fifth metatarsal (outer midfoot). A "no" to walking or a "yes" to bone tenderness means an X-ray the same day, and no training plan until it is done.
Also refer out for visible deformity, numbness or a cold foot, pain above the ankle joint, a repeat sprain or giving way, or no clear improvement within 4–5 days REF-1025.
A negative rule makes a fracture unlikely, not impossible, and says nothing about ligament rupture.
Limitations
The rule was applied by clinicians palpating defined points; self-assessment by an athlete is not validated.
Low specificity: most positives are not fractures.
Full text was read. The original implementation study (Stiell 1994, DOI 10.1001/jama.1994.03510350037034, 2342 adults) reported sensitivity 1.0 for 74 malleolar and 19 midfoot fractures.