Purpose: To analyze the validity of the Ottawa Ankle Rules in our environment as a basis for ordering emergency radiographs after angle and/or mid-foot lesions.

Materials and methods: In this observational study we applied the Ottawa Ankle Rules and prospectively measured the result obtained in patients treated in our emergency department for ankle and/or mid-foot lesions from 1 July 2003 to 1 February 2004. The study excluded polytraumatized and multicontused patients as well as pregnant women and patients who had had the lesion for over 7 days. Radiographs were obtained for all the patients in the study regardless of the result produced by the Ottawa Rules.

Results: 687 patients were included in the study; 111 presented with a fracture. The Ottawa Rules showed a sensitivity of 97.2% (95% CI, mean: 96.0–98.4%). Negative predictive value was 98.5.% (95% CI, range: 96.4–98.7%). Specificity was 35 % (95% CI, range: 31.4–38.6%). Positive predictive value was 22.2% (95% CI, range: 19,1–25.3%).

Discussion and conclusions: The Ottawa Rules are valid in our environment as a decision-making aid when ordering radiographs of patients with angle and midfoot trauma. Applying these rules, savings of up to 30% can be made on radiographs ordered unnecessarily.