The lateral view: A screening method for knee trauma

Rationale and Objectives. The authors performed this study to evaluate whet her any one conventional radiographic view is sufficient as a screening met hod in the detection of acute knee trauma. Materials and Methods. The authors prospectively assessed the efficacy of a single conventional radiograph of the knee in the detection of signs of kn ee fractures in 214 consecutive adults with acute knee trauma. The evaluate d efficacy parameters included specificity, sensitivity, negative predictiv e value (NPV), and positive predictive value. The percentage reduction in t he need for additional conventional radiographs was also calculated. Results. Fifty-three of the 214 patients (24.8%) had a knee fracture. The s ensitivity of the single lateral view in the detection of knee fractures wa s 100% (95% confidence interval [CI] = 94.3, 100). The lateral view of the traumatized knee was normal in 143 patients (66.8%). The probability of not having a fracture if the lateral view was normal (NPV) was also 100% (95% CI = 97.9, 100). The need for additional radiographs was reduced 67%. Conclusion. A single lateral view as a screening tool for knee fractures ha s a very high sensitivity and NPV. Because more than 65% of the patients ha d a normal lateral view in this study, there can be a considerable amount o f savings in terms of radiology services for these patients.