Article Text

Download PDFPDF
Can the Ottawa knee rule be applied to children? A systematic review and meta-analysis of observational studies
  1. D Vijayasankar1,
  2. A A Boyle2,
  3. P Atkinson2
  1. 1
    Peterborough District Hospital, Peterborough, UK
  2. 2
    Addenbrooke’s Hospital, Cambridge, UK
  1. Dr A A Boyle, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 2QQ, UK; adrian.boyle{at}


Background: The Ottawa knee rule (OKR), a clinical decision aid is used to reduce unnecessary radiography. It is not clear whether this rule can be applied to children.

Objective: To establish whether the OKR had adequate sensitivity and acceptable specificity in children to advocate widespread use.

Methods: A systematic review and meta-analysis was conducted of observational studies that examined the diagnostic characteristics of the OKR in children.

Data sources: Relevant English language articles were identified from Medline (1950 to date), EMBASE (1974 to date), CINAHL (1982 to date), the Cochrane Library, Google Scholar and a hand search of bibliographies.

Study selection: Observational studies that included children and have used the OKR for ruling out fractures in children either radiologically or in combination with follow-up.

Results: Four relevant studies were identified. Three studies were suitable for inclusion in the meta-analysis, representing 1130 children. The pooled negative likelihood ratio was 0.07 (95% CI 0.02 to 0.29), the pooled positive likelihood ratio was 1.94 (95% CI 1.60 to 2.36), the pooled sensitivity was 99% (CI 94.4 to 99.8) and the pooled specificity was 46% (CI 43.0 to 49.1). The reduction in radiography was between 30% and 40%.

Conclusion: The OKR has high sensitivity and adequate specificity for children over the age of 5 years. There are not enough good data to advocate application of the OKR in children less than 5 years.

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


  • Funding: This study was funded by the Addenbrooke’s Emergency Medicine Ultrasound Fund. The money was used to purchase computer software.

  • Competing interests: None.