Do You Need an X-Ray?

One of the first questions asked after suffering an injury is, “Do I need an X-Ray?” As with most issues in the medical field, the answer is, “It depends!”  Two of the most frequently injured body parts seen in a physical therapy clinic are the ankle and the knee. Luckily for us and you, our friends across the border in Ottawa developed a few signs that allow us to figure out if you need an x-ray right away or if it is not necessary. Both the Ottawa Knee and and Ottawa Ankle Rules are extremely sensitive tests. This means that they air strongly on the side of caution and were actually found to not miss anyone who needed an x-ray!

Here is where we get into a bit of technical jargon. This is not meant to substitute a full, in person medical evaluation, but is intended to let you know that this information allows a physical therapist to confidently suggest you seek an x-ray or that it may not be necessary.  Studies like this provide us with information that allow PT’s to get your care started earlier and get you back to a life filled with activity!

Here are the Ottawa Ankle Rules:

A. Bony tenderness along bottom 6 cm of posterior edge of fibula or tip of lateral malleolus

B. Bony tenderness along bottom 6 cm of posterior edge of tibia/tip of medial malleolus

C. Bony tenderness at the base of 5th metatarsal

D. Bony tenderness at the navicular

E. Inability to bear weight both immediately after injury and for 4 steps during initial evaluation

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Here are the Ottawa Knee Rules:

  1. <18 years old

  2. Age >55 years

  3. Isolated patellar tenderness without other bone tenderness

  4. Tenderness of the fibular head

  5. Inability to flex the knee to 90°

  6. Inability to bear weight immediately after injury and in the emergency department (4 steps) regardless of limping


This information does not substitute for medical advice, examination or opinion. If you suffer an injury, be sure to seek a professional medical examination.


Stiell IG, McKnight RD, Greenberg GH, McDowell I, Nair RC, Wells GA, Johns C, Worthington JR. Implementation of the Ottawa Ankle Rules. JAMA 1994;271:827-32.

Bachmann LM, Haberzeth S, Steurer J, ter Riet, G. The accuracy of the Ottawa knee rule to rule out knee fractures: a systematic review. Ann Intern Med. 2004 Jan 20;140(2):121-4. Review.

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