Have you injured your knee? Is your knee now swollen or tender? Is the movement of your knee restricted? Can you walk?....Should you get an x-ray??

As clinicians we often use a screening test (the Ottawa Knee Rule) to help guide our decision making in whether or not to refer for an x-ray after a knee injury.

A knee x-ray is required in the following scenarios:

• You are unable to put weight through the leg for 4 steps after the injury occurs (limping is allowed).

OR

• You are aged 55 or over.

OR

• You have tenderness over the bony bump on the outside of your leg, just below your knee (head of fibula).

OR

• You have tenderness of your kneecap only (i.e. nowhere else around the knee is tender).

OR

• You cannot bend your knee more than 90 degrees.

*It is important to note that this screening test is only valid for up to 7 days after the injury has occured.*

These guidelines are for clinicians to combine with their own assessment and clinical reasoning skills. They should not replace an assessment by a medical professional nor medical advice. These guidelines purely act as a screening test to help us rule out the possibility of a bony injury to the knee.

Did you know: x-rays are also often used to assess for arthritic change in the knee BUT they are not necessarily needed for a diagnosis of arthritis to be made (read more here).

Information based on:

Stiell IG, Greenberg GH, Wells GA, McDowell I, Cwinn AA, Smith NA, Cacciotti TF, Sivilotti ML. Prospective validation of a decision rule for the use of radiography in acute knee injuries. JAMA. 1996 Feb 28;275(8):611-5.

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.