Rules based on clinical information such as the Ottawa ankle and knee guidelines have proved to be an effective and safe basis for referring injured patients for radiography. These screening tests have significantly reduced the number of unnecessary radiographs, saving money and radiation exposure for patients. The ability to fully extend the elbow following injury has been suggested as a screening test for radiology, based on a single study of young adults and children. Docherty and colleagues studied the ability of the elbow extension test to screen for clinically significant injury requiring radiograph.
They studied all patients older than 14 years who presented to an urban emergency department for treatment within 24 hours of acute elbow injury. Patients with multiple injuries or altered mental status, including intoxication, were not included in the study. As part of the initial assessment, physicians evaluated the patient's ability to actively extend and lock the elbow with the arm in the supine position. Data were also collected on the uninjured elbow, the mechanism of injury, and the physician's opinion about the need for radiographs. Radiographs were interpreted by radiologists who were unaware of the results of the elbow-extension tests.
Of the 114 patients assessed, 110 had radiography. In the 38 patients with significant injury, 37 were unable to extend the elbow. The one false-negative test was in a patient with a nondisplaced fracture of the radial head. Fifty of the 72 patients without clinically significant bone injury were able to extend the elbow, and 22 were not. The sensitivity of the test was 97 percent, and the positive predictive value was 63 percent. Conversely, the specificity was 69 percent and the negative predictive value was 98 percent.
The authors conclude that this test is sensitive, but not specific, in detecting bone injury after elbow trauma. It is safe and easy to perform the test following acute injury and could reduce the number of radiographs by one half if it is used to select patients for radiology. In patients who can extend the elbow, radiography can be deferred unless the mechanism of injury suggests nondisplaced radial head fracture.