High-yield overview
Clinical decision rule for radiography after acute ankle and midfoot injury
Nearly 100 percent sensitivityfor clinically important fractures — a negative rule reliably excludes fracture
Two zonesankle (malleolar) and foot (midfoot) — assessed separately
30–40 percent fewer X-rayswhen applied correctly in the emergency department
No radiograph neededif the patient can weight-bear 4 steps AND has no bone tenderness at key palpation sites
Critical Must-Knows
- The Ottawa Ankle Rules are a clinical decision rule that identifies which patients with acute ankle or foot injuries need radiography. They were developed to reduce unnecessary imaging while maintaining near-perfect sensitivity for clinically significant fractures.
- For the ANKLE rule: X-ray if there is bone tenderness at the posterior edge or tip of either malleolus, OR inability to weight-bear both immediately after injury and in the emergency department (4 steps).
- For the FOOT rule: X-ray if there is bone tenderness at the navicular or the base of the fifth metatarsal, OR inability to weight-bear as above.
- The rules are among the most validated clinical decision instruments in medicine — replicated across dozens of centres, in adults and children, and across multiple countries. A negative rule means a fracture is extraordinarily unlikely.
Clinical Pearls
- “State the two separate rules (ankle vs foot) with exact palpation sites
- “Frame as a rule-out test — SnNout: high Sensitivity, Negative rules Out
- “Always palpate the proximal fibula separately — Ottawa rules do not screen for Maisonneuve fractures
- “Do not apply if injury is over 48 to 72 hours old, or if there is altered sensorium, deformity, or open wound
What examiners want you to say
State the two separate rules clearly: the ankle rule (malleolar zone) and the foot rule (midfoot zone). Specify the exact palpation sites — posterior edge or tip of the medial and lateral malleolus for the ankle rule, and navicular and base of the fifth metatarsal for the foot rule. Emphasise that the sensitivity approaches 100 percent for clinically important fractures and that the rules reduce radiographs by roughly 30 to 40 percent. Know the limitations: they do not apply to injuries older than 48 to 72 hours, patients with obvious deformity or open fractures, or those with altered sensorium.
The Ottawa Ankle and Foot Rules — Criteria
The rules are applied to two separate anatomical zones. A positive finding in either zone mandates radiography of that zone.
| Criterion | Positive Finding | Action |
|---|---|---|
| Bone tenderness at the posterior edge or tip of the lateral malleolus | Present | Ankle X-ray (AP, lateral, mortise) |
| Bone tenderness at the posterior edge or tip of the medial malleolus | Present | Ankle X-ray (AP, lateral, mortise) |
| Inability to weight-bear 4 steps both immediately after injury and in the ED | Present | Ankle X-ray (AP, lateral, mortise) |
| All above negative | None of the criteria met | No radiograph required |
| Criterion | Positive Finding | Action |
|---|---|---|
| Bone tenderness at the navicular | Present | Foot X-ray (AP, lateral, oblique) |
| Bone tenderness at the base of the fifth metatarsal | Present | Foot X-ray (AP, lateral, oblique) |
| Inability to weight-bear 4 steps both immediately after injury and in the ED | Present | Foot X-ray (AP, lateral, oblique) |
| All above negative | None of the criteria met | No radiograph required |
Mnemonic
**M**alleolus — **A**P/lateral/mortise — **P**osterior edge or tip — **S**teps (4 weight-bearing)Ankle Rule — 'MAPS'
M
Malleolus
Palpate posterior edge and tip of both medial and lateral malleoli
A
Ankle series
AP, lateral, and mortise views if positive
P
Posterior edge
The specific zone to palpate on each malleolus — not just the tip
S
Steps (4)
Unable to take 4 steps both immediately after injury and in the ED
Hook:MAPS — map out the malleoli, then check steps
Mnemonic
**Nav**icular + **5**th metatarsal base = Foot Rule zonesFoot Rule — 'Nav 5'
P
Palpate the navicular — the most prominent bone on the medial midfoot arch
P
Palpate the base of the fifth metatarsal — the lateral midfoot prominence (not the shaft)
T
Tenderness at either site triggers the foot rule and mandates a foot X-ray series
W
Weight-bearing inability (4 steps) is also an independent positive criterion for the foot rule
Hook:Nav 5 — Navicular and 5th metatarsal base are the two foot rule palpation sites
Mnemonic
**B**oth times — **F**our steps — **S**ame rule for ankle and footWeight-bearing test — 'Both Times, Four Steps'
T
The patient must be unable to take 4 steps at BOTH time points: immediately after injury AND in the ED
P
Partial weight-bearing through pain counts as a step — they must be completely unable
I
If they managed 4 steps at either time point, this criterion is negative
T
The weight-bearing criterion applies identically to both the ankle rule and the foot rule
Hook:Both Times, Four Steps — check walking ability at two time points, 4 steps each
Clinical Pearl
Examiners may ask you to demonstrate the palpation sites on a volunteer or diagram. Posterior edge of the malleolus means the posterior ridge — palpate from the tip upward along the posterior margin for roughly 6 cm. The base of the fifth metatarsal is the palpable prominence at the lateral border of the midfoot, not the shaft. The navicular is the most prominent bony point on the medial midfoot arch.
Performance Characteristics and Diagnostic Accuracy
The Ottawa Ankle Rules have been validated in over 30 studies and multiple meta-analyses. Their key strength is the extraordinarily high sensitivity — a negative rule effectively excludes a clinically important fracture.
| Metric | Ankle Rule | Foot Rule | Clinical Significance |
|---|---|---|---|
| Sensitivity | Nearly 100 percent (98–100 percent across studies) | Nearly 100 percent | A negative rule is a highly reliable exclusion test |
| Specificity | Moderate (roughly 30–50 percent) | Moderate | Many positive rules will have no fracture — but you will not miss one |
| Reduction in radiographs | 30–40 percent fewer X-rays | 30–40 percent fewer X-rays | Major cost and time saving in emergency departments |
| Negative predictive value | Near 100 percent | Near 100 percent | Clinicians can safely discharge without imaging if the rule is negative |
Clinical Pearl
The key to explaining the Ottawa rules in a viva is to frame them as a rule-out test (high sensitivity, SnNout: a highly Sensitive test, when Negative, rules Out the disease). The trade-off is moderate specificity, meaning some patients who meet the criteria will have normal X-rays — this is acceptable because the cost of a missed ankle or foot fracture is high.
Limitations and Special Populations
- The rules were developed for acute injuries — apply them within 48 to 72 hours of injury. If the patient presents after this window, the tenderness and weight-bearing findings may not be reliable and a low threshold for imaging is appropriate.
- Patients with altered sensorium (intoxication, head injury, dementia) cannot reliably localise tenderness or report weight-bearing ability — image liberally.
- Obvious deformity, open wounds, or neurovascular compromise are absolute indications for imaging regardless of the rule — do not apply the rules in these settings.
- Children: The rules have been validated in children down to about age 2 with good sensitivity, but the specificity is lower (more X-rays are still ordered). Some paediatric centres adapt the palpation technique for pre-verbal children. A systematic review (Bachmann et al., BMJ 2003) confirmed applicability but urged clinical judgement in the very young.
- Pregnant patients: The rules apply as normal — the decision instrument itself is radiation-free, and avoiding unnecessary radiographs is especially important in pregnancy.
- Patients with pre-existing ankle pathology (prior fracture, arthritis, hardware) may have baseline tenderness that confounds assessment — interpret with caution and a lower imaging threshold.
Clinical Application — Step by Step
- Take a focused history: mechanism of injury (inversion/eversion, twisting, fall from height), time of injury, ability to walk immediately afterwards, prior problems with the ankle or foot.
- Inspect for swelling, bruising, deformity, open wounds, and neurovascular status (dorsalis pedis and posterior tibial pulses, sensation in the toes).
- Palpate systematically — posterior edge and tip of the lateral malleolus, posterior edge and tip of the medial malleolus, navicular, base of the fifth metatarsal, and the proximal fibula (to screen for Maisonneuve-type injuries).
- Assess weight-bearing: ask the patient to take 4 steps (2 on each foot). Each step must bear weight, even if painful. Record whether they could do this immediately after the injury and now.
- Apply the rule: if any criterion is positive, order the appropriate X-ray series (ankle or foot). If all criteria are negative, no radiograph is needed — diagnose a soft-tissue injury (sprain), provide supportive care (RICE — rest, ice, compression, elevation), and advise follow-up if symptoms worsen.
Caution
Always palpate the proximal fibula in any patient with a medial malleolar injury or medial-sided ankle tenderness. A Maisonneuve fracture involves a syndesmotic disruption with a proximal fibular fracture — this will be missed if you only image the ankle. The Ottawa Ankle Rules do not specifically screen for proximal fibular tenderness, so make this a separate mandatory check.
Evidence Base
Evidence
A study to develop clinical decision rules for the use of radiography in acute ankle injuries
Stiell IG, Greenberg GH, McKnight RD, et al. • Ann Emerg Med (1992)
Key Findings:
- Derived the Ottawa Ankle Rules from a prospective cohort of 750 adult patients presenting to emergency departments with acute ankle injuries
- Identified bone tenderness at the malleoli and inability to weight-bear 4 steps as the key predictors of fracture
- Sensitivity of nearly 100 percent for clinically important fractures in the derivation cohort
Clinical implication: Established the original clinical decision rule that became one of the most widely validated instruments in emergency medicine.
Limitation: Single-centre derivation study; required validation in other settings.
Source: Ann Emerg Med 1992;21(4):384-90
Evidence
Decision rules for the use of radiography in acute ankle injuries: refinement and prospective validation
Stiell IG, McKnight RD, Greenberg GH, et al. • JAMA (1993)
Key Findings:
- Multicentre prospective validation in over 2,000 patients across community and university hospitals
- Sensitivity of 100 percent for clinically significant fractures — no fractures were missed when the rule was negative
- Potential to reduce ankle radiographs by approximately 36 percent
Clinical implication: Confirmed that the Ottawa Ankle Rules were safe, reproducible, and effective across diverse clinical settings.
Limitation: Adults only in this study; paediatric validation came later.
Source: JAMA 1993;269(9):1127-32
Evidence
Accuracy of the Ottawa Ankle and Foot Rules to exclude fractures: a systematic review
Bachmann LM, Kolb E, Koller MT, Steurer J, ter Riet G • BMJ (2003)
Key Findings:
- Systematic review and meta-analysis of 32 studies with over 25,000 patients
- Pooled sensitivity for the ankle rule was 98 percent (some studies 100 percent); for the foot rule, similarly high
- Specificity was approximately 40 percent for the ankle rule and 30 percent for the foot rule
- Computed that applying the rules could reduce radiographs by 30 to 40 percent
Clinical implication: The Ottawa rules have the highest quality evidence of any clinical decision rule for extremity trauma and should be standard practice.
Limitation: Heterogeneity in study populations and rule application across included studies.
Source: BMJ 2003;326(7386):417
Evidence
The Ottawa Ankle Rules in children: a systematic review and meta-analysis
Dowling S, Spooner CH, Liang Y, et al. • Acad Emerg Med (2009)
Key Findings:
- Systematic review confirming high sensitivity (approximately 99 percent) for clinically important fractures in children
- Specificity was lower than in adults, meaning more imaging is still performed
- Recommended for use in children older than age 2, with appropriate clinical judgement in pre-verbal children
Clinical implication: The Ottawa Ankle Rules can be safely applied to the paediatric population, further broadening their clinical utility.
Limitation: Fewer high-quality paediatric studies compared with the adult literature.
Source: Acad Emerg Med 2009;16(4):277-87
Guidelines, Registries and Global Practice
NICE (UK) — NG41 (Fractures: assessment and management, 2016, updated 2022)
- Recommendation
- Recommends the Ottawa Ankle Rules as the clinical decision tool for determining the need for radiography in acute ankle injuries in adults.
AAOS (US) — Clinical Practice Guideline on Acute Achilles Tendon Rupture and Ankle Injury
- Recommendation
- Supports the use of validated clinical decision rules (Ottawa) to reduce unnecessary imaging in acute ankle and foot injuries.
ACEP (American College of Emergency Physicians)
- Recommendation
- Endorses the Ottawa Ankle Rules as a validated, high-sensitivity clinical decision instrument. Application is recommended as standard emergency department practice.
Australian Commission on Safety and Quality in Health Care
- Recommendation
- Includes the Ottawa Ankle Rules in its resource stewardship initiatives to reduce low-value imaging.
Global practice variation: In many high-income emergency departments, the rules are embedded into triage protocols and electronic decision support. In lower-resource settings, where radiography may be limited or costly, the Ottawa rules are especially valuable for rationing imaging to those who truly need it. Some centres in Europe and Asia report near-universal uptake, while others cite medicolegal concerns as a barrier — clinicians fear missing a rare fracture despite the evidence. The overall trend globally is toward broader adoption.
Exam Viva
Practise clinical reasoning and management decisions out loud
Viva scenarioStandard
Clinical prompt
“A 28-year-old man presents to the emergency department 2 hours after inversion injury to his right ankle while playing basketball. He was unable to walk off the court. On examination there is swelling over the lateral ankle, tenderness at the posterior edge of the lateral malleolus, and he cannot take 4 steps in the department. How do you apply the Ottawa Ankle Rules?”
Practical approach
This patient has a positive Ottawa Ankle Rule. The ankle rule mandates radiography when there is bone tenderness at the posterior edge or tip of either malleolus, OR inability to weight-bear 4 steps both immediately after injury and in the ED. He has both: tenderness at the posterior edge of the lateral malleolus, and inability to walk 4 steps at the scene and now. I would order a full ankle X-ray series — AP, lateral, and mortise views. I would also palpate the proximal fibula to screen for a Maisonneuve-type injury, check neurovascular status (dorsalis pedis and posterior tibial pulses, sensation), and assess the medial malleolus and syndesmotic squeeze. If X-rays show a fracture, I would classify and manage accordingly. If X-rays are negative, I would still treat this as a significant soft-tissue injury with supportive care and follow-up.
Key clinical points
State both criteria clearly: malleolar tenderness and inability to weight-bear 4 steps
This patient meets both criteria — ankle X-ray is mandatory
Always palpate the proximal fibula to exclude a Maisonneuve fracture
Negative X-ray does not mean negative injury — soft-tissue injuries still need management
Common pitfalls
Forgetting to check weight-bearing at both time points (immediately after injury AND in the ED)
Only palpating the lateral malleolus and missing medial malleolar tenderness
Not screening the proximal fibula for a Maisonneuve injury
Further questions
“What if the X-ray shows a fracture at the base of the fifth metatarsal — how does that change things?”
“How do the Ottawa Ankle Rules perform in children?”
“What is the significance of the mortise view specifically?”
Viva scenarioAdvanced
Clinical prompt
“A 45-year-old woman twists her foot on uneven ground. She can walk but with a limp. There is no tenderness at either malleolus, but there is marked tenderness over the navicular on the medial midfoot and at the base of the fifth metatarsal laterally. She can manage 4 steps in the department. How do you apply the Ottawa Foot Rules?”
Practical approach
This patient has a positive Ottawa Foot Rule. The foot rule mandates radiography when there is bone tenderness at the navicular OR the base of the fifth metatarsal. She has tenderness at both sites. Although she can weight-bear 4 steps, the bone tenderness criterion alone triggers the rule. I would order a foot X-ray series — AP, lateral, and oblique views — to look for a navicular fracture, a fifth metatarsal base fracture (including a Jones fracture versus an avulsion fracture), or a midfoot Lisfranc-type injury. I would also carefully assess the tarsometatarsal joint line and perform a careful neurovascular examination. If X-rays are negative but clinical suspicion remains high (especially for a Lisfranc injury), I would consider weight-bearing foot views or CT.
Key clinical points
The foot rule and ankle rule are separate — apply the correct one for the anatomical zone
Bone tenderness at the navicular or fifth metatarsal base is sufficient to trigger the foot rule, regardless of weight-bearing ability
A negative rule does not exclude all pathology — it specifically targets clinically important fractures
Consider Lisfranc injury in any midfoot tenderness pattern, especially with a twisting mechanism
Common pitfalls
Applying the ankle rule instead of the foot rule for midfoot symptoms
Dismissing the patient because she can weight-bear — the bone tenderness criterion is already positive
Calling any fifth metatarsal base fracture a 'Jones fracture' — distinguish avulsion fractures (tuberosity) from true Jones fractures (metaphyseal-diaphyseal junction)
Further questions
“What is the difference between a Jones fracture and an avulsion fracture of the fifth metatarsal tuberosity, and why does it matter?”
“How would you investigate a suspected Lisfranc injury with normal plain X-rays?”
“What are the Ottawa rules' limitations in the first 48 hours versus delayed presentation?”
Exam day cheat sheet
Ottawa Ankle and Foot Rules — Exam Cheat Sheet
Ankle Rule (malleolar zone)
- X-ray if: bone tenderness at posterior edge or tip of the lateral malleolus
- X-ray if: bone tenderness at posterior edge or tip of the medial malleolus
- X-ray if: unable to weight-bear 4 steps both immediately after injury AND in the ED
- All three negative: no radiograph needed — diagnose soft-tissue injury
Foot Rule (midfoot zone)
- X-ray if: bone tenderness at the navicular
- X-ray if: bone tenderness at the base of the fifth metatarsal
- X-ray if: unable to weight-bear 4 steps (both time points, same as ankle rule)
- All three negative: no radiograph needed
Key performance and caveats
- Sensitivity approximately 98 to 100 percent — a negative rule effectively excludes fracture
- Reduces radiographs by roughly 30 to 40 percent when correctly applied
- Does NOT apply to: delayed presentation over 48 to 72 hours, altered sensorium, obvious deformity, open fractures
- Always palpate the proximal fibula separately — Ottawa rules do not screen for Maisonneuve fractures
- Validated in adults and children (over age 2) across multiple countries and healthcare systems