External validation of the Ottawa knee rules in an urban trauma center in the United States

OBJECTIVE. We evaluated the Ottawa knee rules in a high-volume teaching hos pital in the United States to determine whether the rules could be safely u sed to decide whether patients with acute blunt knee trauma should undergo radiography, SUBJECTS AND METHODS. During a 13-month period, 378 patients with acute blu nt knee trauma were prospectively examined using the Ottawa knee rules. Dat a collected included the presence or absence of fracture predictors and the results of radiography. RESULTS, A fracture was seen in 43 (11%) of the 378 patients who met inclus ion criteria. The knee rules predicted 42 of the 43 fractures; sensitivity was 98%, and specificity was 19%. Radiography of 65 patients (17%) who had no predictors for fracture could have been avoided if the knee rules had be en used to screen for radiography. CONCLUSION. The Ottawa knee rules are highly sensitive for fracture in this setting and may safely be used to decide whether patients with acute blunt knee trauma should undergo radiography.