Knee injuries are very common. The cost of routine radiography is high. Therefore the Ottawa Knee Rule was developed and validated as a clinical decision rule for radiography.
This study assesses the impact of implementation of this rule on actual use of radiographs, waiting times and direct medical changes.
3907 nonpregnant adults with acute knee injuries were included in this nonrandomized controlled clinical trial. The outcomes were patients referred for radiographs, patient satisfaction with treatment and changes.
In before and after periods there was a 26.4% reduction in referrals for knee radiography in the intervention group (77.6% to 57.1%) compared with a 1.3% reduction in the control group (76.9% to 75.9%).
At intervention, physicians interpreted the rule accurately for 97.7% of patients, and there was excellent interobserver agreement.
In the after-intervention group, patients who did not have knee radiography spent significantly less time in the emergency department than patients undergoing radiography (85.7 vs 118.8 minutes). When surveyed 95.7% of patients without radiographs and 98.7% of patients with radiographs were satisfied with the treatment.
The mean charges were significantly lower in the nonradiography group (80 vs 183 dollars). All clinically important fractures were identified by the Ottawa Knee Rule for a sensitivity of 1.0 and a negative predictive value of 1.0.
