We tested the hypothesis that it was possible to decrease the number of x-ray films obtained after a knee trauma without delayed fracture diagnosis by means of the Ottawa knee rules.
Patients underwent routine x-ray studies of the injured knee during the first stage of the study and selective x-ray studies during the second stage. All patients were followed-up for 6 months after the trauma.
One hundred thirty-eight patients were included in the first stage; 57 had negative Ottawa criteria (no fracture was observed). The Ottawa rules indicated that 41% of the x-ray studies could have been avoided. One hundred seventy-eight patients were included in the second stage; 63 patients had negative Ottawa criteria (no fracture was diagnosed during the follow-up). Thirty-five percent of the x-ray studies were avoided.
Ottawa rules allowed decreasing the number of x-ray studies performed after a knee trauma by 35%, with a sensitivity for knee fracture detection of 100%.