Study objective: To validate the Ottawa Ankle Rules (OAR) to predict significant fractures in a Danish clinical setting.

Methods: We designed an interventional clinical study in the emergency department, Kolding Hospital. The intervention and control groups consisted of all patients presenting with a blunt trauma of the ankle within 12 months. Patients in the first 6 months were included in the control group. The intervention consisted of a 45 minutes introduction to the OAR to the new group of junior doctors starting in the emergency department. Flyers and poster were distributed. There were 854 and 1006 patients respectively in the control and intervention group.

Results: The main outcome of the study was a reduction in the number of preformed radiographs and an increase in diagnostic sensitivity. In the control group 62% of the patients were referred to radiographs, while only 57% in the intervention group. OAR had a sensitivity of 0.988, while the usual examinations techniques in the control group resulted in a sensitivity of 0.969. The use of OAR resulted in an increase in diagnostic specificity from 0.442 in the control group to 0.513 in the intervention group. The negative predictive value of OAR was 0.995. The rules failed in identifying 2 ankle fractures: a shaft fracture of the fifth metatarsal and 6 mm avulsion of the distal fibula. Both were diagnosed within the first week and treated conservatively, when returning to the hospital, as the OAR recommended in cases of no clinical improvement. When using the OAR, the radiology department would approximately perform 176 ankles and midfoot x-rays less a year, which is equivalent to 16%.

Conclusion: Use of the OAR in a Danish clinical setting resulted in an increased diagnostic safety in detecting significant ankel fractures and in a reduction of unnecessary radiographs of the ankle and midfoot. We believe that the implementation of OAR could be beneficial to many emergency departments in Denmark and possibly in other similar settings.