Diagnostic accuracy of the Ottawa Knee Rule in adult acute knee injuries: a systematic review and meta-analysis

Objectives: This systematic review and meta-analysis aimed to evaluate the current evidence on the diagnostic accuracy of the Ottawa Knee Rule (OKR) for acute knee injuries in adults. Methods: A literature search of Embase (Elsevier), MEDLINE (U.S. National Library of Medicine), PubMed and Scopus databases (1995 to date; English language) was performed and the relevant references were assessed. Original articles documenting OKR use by emergency physicians to assess adult acute knee injuries were included. Study methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Results of eligible studies were pooled using random effects or fixed effects modelling to calculate the diagnostic performance of the OKR. The Higgins I2 test and Begg’s association test were performed to assess between-study heterogeneity and publication bias respectively, with Spearman’s correlation test for threshold effect. Results: Eight studies, including 7385 patients, were enrolled and pooled using the random effects model. Sensitivity, specificity, negative likelihood ratio, positive likelihood ratio and diagnostic odds ratio were 0.99 (95% CI, 0.97 to 1.00), 0.49 (95% CI, 0.47 to 0.51), 0.07 (95% CI, 0.02 to 0.24), 1.86 (95% CI, 1.72 to 2.01) and 25.10 (95% CI, 7.18 to 87.70) respectively. Based on the QUADAS-2 criteria, most studies presented low risk of bias and concern regarding applicability. Conclusions: Application of the OKR can rule out knee fracture and thus avoid unnecessary radiography. These results also translate to improved efficiency, lower medical costs and reduced waiting times. Key Points: • The Ottawa Knee Rule helps clinicians to rule out fracture in adults with an acute knee injury. • The rule allows a reduction in radiography requests, patient waiting time in the emergency department and healthcare costs.