Does the normal four steps weight-bearing rule predict the need for radiography in cases of blunt ankle trauma?

Background: Ankle injuries are one of the most common complaints of patients presenting to emergency departments (ED). The Ottawa ankle rules (OAR) was introduced to help physicians to decide who may require x-ray for blunt injuries. The present study aimed at validating the four steps weight-bearing rule of OAR as a sole criterion.    Methods: This prospective observational study was conducted on 214 patients with acute ankle injury who referred to 3 emergency departments over a 7-months period in 2008. Main outcome measures of this survey included the sensitivity, specificity, positive and negative predictive values, and the likelihood ratios (positive and negative) of the four steps weight-bearing rule.    Results: In this study, 34 fractures were found among the patients. The decision rule had a sensitivity of 0.88 and specificity of 0.61 in detecting all midfoot and ankle fractures. Application of this rule by emergency medicine residents resulted in a 47% reduction in the use of midfoot and ankle radiography.    Conclusion: Applying a four steps weight-bearing rule as a sole criterion to detect ankle fractures is not as accurate and sensitive as OAR. Solitary application of this rule may lead to an increasing number of missed fractures compared with OAR.