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. doi: 10.7326/0003-4819-140-5-200403020-00013.


Background: The Ottawa knee rule is a clinical decision aid that helps rule out fractures and avoid unnecessary radiography.

Purpose: To summarize evidence about the accuracy of the Ottawa knee rule.

Data sources: Relevant English- and non-English-language articles were identified from PreMEDLINE and MEDLINE (1966-2003), EMBASE (1980-2003), CINAHL (1982-2003), BIOSIS (1990-2003), the Cochrane Library (2002, Issue 3), the Science Citation Index database, reference lists of included studies, and experts.

Study selection: Articles were included if they reported enough information to determine the sensitivity and specificity of the Ottawa knee rule for detecting fractures confirmed either radiologically or in combination with follow-up.

Data extraction: Two reviewers independently extracted data on study samples, the ways that the Ottawa knee rule was used, and methodologic characteristics of studies.

Data synthesis: Of 11 identified studies, 6 involving 4249 adult patients were considered appropriate for pooled analysis. The pooled negative likelihood ratio was 0.05 (95% CI, 0.02 to 0.23), the pooled sensitivity was 98.5% (CI, 93.2% to 100%), and the pooled specificity was 48.6% (CI, 43.4% to 51.0%).

Conclusion: A negative result on an Ottawa knee rule test accurately excluded knee fractures after acute knee injury. However, because the rule is calibrated toward 100% sensitivity and actual fracture prevalences are usually low, large-scale, multicentered studies are still needed to establish the cost-effectiveness of routinely implementing the rule.

Publication types

  • Meta-Analysis
  • Review
  • Systematic Review

MeSH terms

  • Decision Support Techniques
  • Emergency Service, Hospital
  • Fractures, Bone / diagnosis*
  • Fractures, Bone / diagnostic imaging
  • Humans
  • Injury Severity Score*
  • Knee Injuries / diagnosis*
  • Knee Injuries / diagnostic imaging
  • Predictive Value of Tests
  • Radiography / statistics & numerical data