UMEM Educational Pearls

Category: Orthopedics

Title: The Ottawa Rules

Keywords: Ottawa, Ankle, Knee, Foot (PubMed Search)

Posted: 2/28/2009 by Michael Bond, MD (Updated: 9/24/2021)
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Most people are familiar with the Ottawa Ankle Rules, but there are also Ottawa Knee and Foot rules.  The Ottawa rules help to limit the number of x-rays you may need in patients that present with ankle, foot or knee pain after an injury.

The Ottawa Ankle Rule

An ankle x-ray is only needed if there pain in the mallelolar area and any of the following:

  • Bone tenderness at the posterior tip of the base of the lateral mallelous
  • Bone tenderness at the posterior tip of the base of the medial mallelous
  • Inability to weight bear immediately and in the Emergency Department

The Ottawa Foot Rule

A foot x-ray is only needed if there is pain in the midfoot and any of the following:

  • Bone tenderness at the base of the 5th metatarsal
  • Bone tenderness over the navicular
  • Inability to weight bear immediately and in the Emergency Department

The Ottawa Knee Rule

A knee x-ray is only needed for knee injury patients when they have any of the following:

  • Age 55 or over
  • Isolated tenderness of the patella (no bone tenderness of the knee other than the patella)
  • Tenderness at the head of the fibula
  • Inability to flex to 90 degrees
  • Inability to weight bear both immediately and in the Emergency Department (4 steps - unable to transfer weight twice onto each lower limb regardless of limping).