CLINICAL DECISION RULES DISCRIMINATE BETWEEN FRACTURES AND NONFRACTURES IN ACUTE ISOLATED KNEE TRAUMA

Design: A prospective survey of emergency department patients over a 7 -month period. Standardized data forms were completed by emergency phy sicians, residents, and certified physician assistants. Setting: A lar ge suburban community teaching hospital. Participants: Two hundred for ty-two patients older than 17 years with isolated knee injuries sustai ned less than 24 hours previously. Results: We constructed a clinical decision model, calculating sensitivity, specificity, and odds ratios. Twenty-eight patients (11.6%) had fractures, with the patella the mos t commonly fractured osseous structure. Patients able to walk without limping had not experienced a fracture, nor had patients with twist in juries without effusion. Sensitivity of this model for detecting fract ure was 1.0 (99% confidence interval, .97 to 1.0), and specificity was .337 (99% confidence interval, .26 to .42). Conclusion: Clinical deci sion rules are effective in detecting knee fractures with 100% sensiti vity and with sufficient specificity to eliminate 29% of knee radiogra phs in the ED. These findings require prospective validation.