Implementation of the Ottawa Knee Rule for the use of radiography in acute knee injuries.

CONTEXT The Ottawa Knee Rule is a previously validated clinical decision rule that was developed to allow physicians to be more selective and efficient in their use of plain radiography for patients with acute knee injuries. OBJECTIVE To assess the impact on clinical practice of implementing the Ottawa Knee Rule. DESIGN Controlled clinical trial with before-after and concurrent controls. SETTING Emergency departments of 2 teaching and 2 community hospitals. PATIENTS All 3907 consecutive eligible adults seen with acute knee injuries during two 12-month periods before and after the intervention. INTERVENTION During the after period in the 2 intervention hospitals, the Ottawa Knee Rule was taught to all house staff and attending physicians who were encouraged to order knee radiography according to the rule. MAIN OUTCOME MEASURES Referral for knee radiography, accuracy and reliability of the rule, mean time in emergency department, and mean charges. RESULTS There was a relative reduction of 26.4% in the proportion of patients referred for knee radiography in the intervention group (77.6% vs 57.1 %; P<.001), but a relative reduction of only 1.3% in the control group (76.9% vs 75.9%; P=.60). These changes over time were significant when the intervention and control groups were compared (P<.001). The rule was found to have a sensitivity of 1.0 (95% confidence interval [CI], 0.94-1.0) for detecting 58 knee fractures. The K coefficient for interpretation of the rule was 0.91 (95% CI, 0.82-1.0). Compared with nonfracture patients who underwent radiography during the after-intervention period, those discharged without radiography spent less time in the emergency department (85.7 minutes vs 118.8 minutes) and incurred lower estimated total medical charges for physician visits and radiography (US $80 vs US $183). CONCLUSIONS Implementation of the Ottawa Knee Rule led to a decrease in use of knee radiography without patient dissatisfaction or missed fractures and was associated with reduced waiting times and costs. Widespread use of the rule could lead to important health care savings without jeopardizing patient care.