Abstract

Background
We performed this study to validate the Ottawa Knee Rule for determining the need for radiography in patients with acute knee injuries. Methods: A prospective study was performed from August 2001 to July 2002. The patient population was composed of a convenience sample of 242 eligible adults out of 453 adult patients with acute knee injuries. The attending emergency physician assessed each patient for standardized clinical variables and determined the need for radiography according to the decision rule. After the findings of clinical evaluation had been recorded, radiography was performed in each patient, irrespective of the determination of the rule. The rule was assessed for its ability to correctly identify fracture of the knee. Results: The decision rule had a sensitivity of 1.0 and a specificity of 0.46. The potential reduction in use of radiography was estimated to be 40%. The probability of a fracture, existing when the decision rule was negative, is estimated to be 0%. Conclusion: A prospective validation has shown the Ottawa Knee Rule to be 100% sensitive for identifying fractures of the knee and to have the potential to allow physicians to reduce the use of radiography in patients with acute knee injuries.

• Keywords: Ottawa Knee Rule, Acute knee injury, Knee X-ray