Purpose: The Ottawa Knee Rules were developed in order to determine the need for radiographs after acute knee injury secondary to the risk of fracture.
Rule:
1. Age greater than 55
2. Tenderness at the head of the fibula
3. Isolated tenderness of the patella during palpation
4. Inability to flex the knee to 90 degrees
5. Inability to bear weight immediately and upon ER evaluation
| Item | |
| SN | 0.99 |
| SP | 0.47 |
| +LR | 0.06 |
SN = sensitivity – ‘SnOut’ helps rule out a disease (higher number is better – >0.9 is excellent)
SP = Specificity – ‘SpIn’ helps rule in a disease (higher number is better – greater than 0.90 is excellent))
+LR = positive likelihood ratio – ratio of positive test results in a patients with the pathology (true positives) higher number is better (> 10 is excellent)
-LR = negative likelihood ratio – ratio of negative test results in a patients with the pathology (false negatives) lower number is better (< 0.1 is excellent)
PPV = positive predictive value – percentage of patients who both test positive & have the disease (true positives)
NPV = negative predictive value – percentage of patients who both test negative & do not have disease (true negatives)
References:
1. Bachmann LM, Haberzeth S, Stuerer J, ter Riet G. The accuracy of the Ottawa Knee Rule to rule out knee fractures: a systematic review. Ann Intern Med. 2004; 140: 121–124.
2. Vijaysankar D, Boyle AA, Atkinson P. Can the Ottawa Knee Rule be applied to children? A systematic review and meta analysis of observational studies. Emerg Med J. 2009; 26: 250-253.
