Validation of the Ottawa ankle rules in a Danish emergency department

The Ottawa ankle rules (OAR) is a tool physicians may use to determine whether or not to perform an x-ray after an ankle or midfoot distortion or blunt trauma to these structures. The rationale of using the OAR is to exclude a fracture by means of clinical examination without resort to x-rays, and thereby limiting the use of x-rays, time, costs, etc. The principle of the OAR is that an ankle x-ray is only required when there is bone tenderness along the distal six centimetres of the posterior part of the medial or lateral malleolus, or when the patient is unable to bear weight immediately after the accident and in the emergency department (ED). Similarly, an x-ray of the midfoot is required only when there is bone tenderness at the base of the 5th metatarsal or the navicular bone, or when the patient is unable to bear weight immediately after the accident and also in the ED. Our hypothesis was that by introducing the OAR, we would reduce the use of x-rays without increasing the number of missed fractures.

The study was designed as an intervention study with 882 patients in the control group and 1,014 patients in the intervention group. The intervention consisted of several OAR implementation measures.

Before use of the OAR, 62% had an x-ray taken. This proportion was reduced to 57% with the introduction of the OAR. We registered a significant reduction (p < 0.001) in x-ray without increasing the number of missed fractures.

The OAR may reduce the number of x-rays and possibly also save costs and time if implemented in Denmark.