What are the Ottawa foot X-ray (Ottawa foot radiograph) rules for determining when to order an X-ray for a foot injury?

Ottawa Foot X-ray Rules

A foot X-ray is required only if there is pain in the midfoot AND any one of the following: point bone tenderness of the navicular, point bone tenderness of the base of the fifth metatarsal, or inability to bear weight or walk 4 steps immediately after injury or in the emergency department. 1

Ottawa Foot Rules Criteria

• The Ottawa foot rules are clinical decision guidelines recommended by the American College of Radiology to determine when radiographs are necessary for patients with foot injuries 1
• These rules have 99% sensitivity for detecting fractures while reducing unnecessary imaging by approximately 30% 1
• The rules apply specifically to midfoot injuries and have distinct criteria from the Ottawa ankle rules 1, 2

When to Order Foot X-rays

• Order foot X-rays only when BOTH of these criteria are met:
  1. Pain in the midfoot region AND
  2. At least ONE of the following:
     • Point bone tenderness at the navicular bone 1, 2
     • Point bone tenderness at the base of the fifth metatarsal 1, 2
     • Inability to bear weight for four steps both immediately after injury and in the emergency department 1

Clinical Performance of Ottawa Foot Rules

• The Ottawa foot rules have demonstrated high sensitivity (96.8-100%) for detecting clinically significant fractures 1
• Implementation of these rules can reduce X-ray usage by approximately 5-10% without increasing the number of missed fractures 3, 4
• The negative predictive value is excellent (95-100%), making these rules highly reliable for excluding fractures 5, 6

Exclusionary Criteria - When NOT to Use Ottawa Foot Rules

The Ottawa foot rules should not be used or should be used with great caution in the following situations:

• Penetrating trauma 7, 1
• Pregnancy 7, 1
• Presence of skin wounds 7, 1
• Patients transferred with radiographs already taken 7, 1
• Injuries older than 10 days 7, 1
• Return visits for continued traumatic foot pain 7, 1
• Polytrauma patients 7, 1
• Altered mental status 7, 1
• Neurologic abnormality affecting the foot (including diabetic neuropathy) 7, 1
• Underlying bone disease 7, 1
• Children under 5 years of age 1

Standard Radiographic Views When Indicated

• When X-rays are indicated based on the Ottawa foot rules, three standard views should be obtained: anteroposterior, lateral, and mortise views 1
• Weight-bearing radiographs provide important additional information for fractures of uncertain stability 1

Clinical Scenarios Not Addressed by Ottawa Rules

• The Ottawa foot rules do not address:
  • Trauma to metatarsal heads and toes 7, 1
  • Acute tendon injuries 7
  • Penetrating trauma with concern for foreign body in soft tissues 7, 1

Common Pitfalls and Caveats

• Ensure proper assessment of all criteria before ruling out the need for imaging 1
• Consider age-specific modifications for elderly patients to improve sensitivity 1
• In polytrauma patients, approximately 25% of midfoot fractures identified on CT are overlooked on radiographs, making CT essential for appropriate treatment planning 7
• The ability to walk again within 48 hours after trauma is an auspicious sign and indicates a good prognosis 1

Implementation Tips

• Training healthcare providers in proper application of the Ottawa foot rules significantly improves compliance and reduces unnecessary X-rays 4
• Ultrasound may be a useful adjunct to the Ottawa rules, potentially further reducing the need for X-rays in positive Ottawa rule patients 5
• The rules have been validated for use by both physicians and properly trained non-physician providers 8