Clinical decision rules discriminate between fractures and nonfractures in acute isolated knee trauma.

Abstract

To develop criteria that optimize clinical decisionmaking in the use of radiography after isolated knee trauma in adults. A prospective survey of emergency department patients over a 7-month period. Standardized data forms were completed by emergency physicians, residents, and certified physician assistants. A large suburban community teaching hospital. Two hundred forty-two patients older than 17 years with isolated knee injuries sustained less than 24 hours previously. We constructed a clinical decision model, calculating sensitivity, specificity, and odds ratios. Twenty-eight patients (11.6%) had fractures, with the patella the most commonly fractured osseous structure. Patients able to walk without limping had not experienced a fracture, nor had patients with twist injuries without effusion. Sensitivity of this model for detecting fracture was 1.0 (99% confidence interval, .97 to 1.0), and specificity was .337 (99% confidence interval, .26 to .42). Clinical decision rules are effective in detecting knee fractures with 100% sensitivity and with sufficient specificity to eliminate 29% of knee radiographs in the ED. These findings require prospective validation.