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Editor,—In their study to verify the Ottawa ankle rules Perry et al point out “the potential dangers of rigidly adhering to decision rules”.1 The study discovered that four malleolar fractures would have been missed had the guidelines (per the Ottawa ankle rules2) been applied—that is, these patients would not have had radiography.
The data from the study were derived from the emergency department ankle “stamper”, which comprises 12 parameters. Of these they selected four: age, posterior malleolar tenderness (which malleolus was not specified), inability to weight bear immediately, and inability to weight bear in the emergency department. This information was deemed adequate to meet the study's requirements.
However, age is relevant only as an eligibility criterion for application of the rules—it does not impact on decision making regarding radiography thereafter. Secondly, the failure to specify which malleolus was tender detracts from attempts at verification—the rules specify both malleoli must be assessed. Moreover, the study (and the stamper!) ignores the second part of the ankle rules entirely—that is, navicular zone and fifth metatarsal zone tenderness.
In view of the authors' decision to apply only part of the Ottawa ankle rules, and the disregard for one of the malleoli, it seems inappropriate to conclude that “although useful, decision rules should be used with care and cannot replace clinical judgment and experience”.
Dr Perry replies
Thank you very much for giving me the opportunity to reply to Dr McCann's letter. I disagree with Dr McCann's comments about age. The Ottawa ankle rules clearly state that plain radiography is indicated if the patient is aged 55 years or greater.1
The authors accept that our stamper did not specify which malleolus had been examined and may, theoretically, have resulted in some patients being recorded as “Ottawa negative” inappropriately. However, it is clearly stated in the discussion that the four missed fracture patients had their case notes reviewed and there were no apparent reasons why these fractures were not identified. This included ensuring adequate documentation of the clinical examinations.
It was never the intention to study the second rule concerning foot radiography and patients with bony tenderness of the foot were, therefore, excluded.
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