Ottawa Knee, Ankle, and Foot Rules

Plain film x-rays are indicated if presence of traumatized extremity and ANY of the following findings:

Ottawa Knee Rules

1. Patient age ≥55 years
2. Isolated tenderness of the patella
3. Tenderness at the head of the fibula
4. Inability to flex knee to 90 degrees

5. Inability to walk 4 steps both immediately and in the ED

6. Performance characteristics (Emparanza et al, Ann Emerg Med (2001))

   • Sensitivity 100%
   • Reduced x-ray need by 49%

Ottawa Ankle Rules

Exclusion criteria: Patients <18 years old

1. Most distal 6 cm of fibula (lateral malleolus): Tenderness at or along posterior edge
2. Most distal 6 cm of tibia (medial malleolus): Tenderness at or along posterior edge
3. Inability to walk 4 steps both immediately and in the ED

Ottawa Foot Rules

1. Tenderness at base of 5th metatarsal
2. Tenderness over navicular bone
3. Inability to walk 4 steps both immediately and in the ED

Combined Ottawa Ankle and Root Rules

Performance characteristics (Mayer D. BMJ (2009))

• Sensitivity = 97.8%
• Specificity = 31.5%
• Negative LR = 0.07

Pearls

Pediatric patients: Variable validation data for Ottawa ankle and foot rules

• General rule: Ligaments are stronger than growth plates in children.
• OK to use knee rules in pediatrics based on (Bulloch et al. Ann Emerg Med, 2003)
  • Mean age in study = 11.8 years +/- 3.1 years
  • Inclusion age range = 2-16 years old

References

• Mayer D. The injured ankle and foot. BMJ. 2009 Aug 7;339. [PubMed]
• Bulloch B. et al. Validation of the Ottawa Knee Rule in children: a multicenter study. Ann Emerg Med. 2003 Jul;42(1):48-55. [PubMed]
• Emparanza JI. et.al.Validation of the Ottawa Knee Rules. Ann Emerg Med. 2001 Oct;38(4):364-8. [PubMed]