Prediction of Fracture in Patients with Acute MusculosKeletal Ankle Trauma

Abstract

X-rays taken for ankle trauma contribute significantly to the cost of health care in this country. In an attempt to find clinical correlates of ankle fracture 36 detailed historical and physical examination variables were collected from 587 consecutive patients with ankle trauma, and ankle x-rays were taken of all patients. The association of each variable with the final diagnosis of fracture, rupture, or sprain was tested; 21 variables were significant predictors of fracture (vs. sprain and rupture) and 15 were not significantly associated with final di agnosis. The variables were used in a linear discriminant analysis to develop a rule which would predict the final diagnosis. If only those patients predicted by the rule to have fractures had been x-rayed, all patients with fracture would have been identified but more than a fourth of all ankle trauma patients would have been spared x-rays. This compares favorably with a recently published rule that did not assess sensitivity. A simulated prospective evaluation suggests that these results are stable, but that up to 10% of the fractures could be missed on the first visit. Although current practice is not well documented, it appears that use of this rule could yield substantial cost savings. Key words: linear discriminant analysis; diagnosis; ankle trauma; fractures. (Med Decis Making 8:40-47, 1988)