Ottawa Knee Rule saves 33 minutes, $133

A recent study out of the University of Ottawa in Ontario, Canada, assessed the impact of the Ottawa Knee Rule on 4,000 patients at two teaching and two community hospitals in Ottawa. The study found that implementation of the rule led to a 26.4% reduction in use of radiography, with no missed fractures.1 Patient satisfaction was enhanced, and wait times and costs were reduced. Those discharged saved an average of 33 minutes and $133. Under the Ottawa Knee Rule, an X-ray is required for knee injury patients who meet at least one of the following criteria:

· age 55 or older;

· isolated tenderness of the patella;

· tenderness at the head of the fibula;

· inability to flex the knee 90 degrees;

· inability to bear weight both immediately and in the ED.

Guidelines on high-volume, small-ticket items like knee X-rays are often ignored, say the investigators.


1. Stiell IG, Wells GA, Hoag RH, Implementation of the Ottawa Knee Rule for the use of radiography in acute knee injuries. JAMA 1997; 278:2,075-2,079.