Validation of the Sonographic Ottawa Foot and Ankle Rules (SOFAR) Study in a Large Urban Trauma Center.

Abstract

Introduction: Differentiating the severity of acute ankle injuries is a common problem in the emergency department (ED). The Ottawa Foot and Ankle Rules (OFAR) were designed to obviate the need for unnecessary x-rays. Although these rules have been determined to be very sensitive, they lack the specificity necessary to make them practically useful for a condition in which a misdiagnosis could result in a significant disability. Our study objective was to determine if the addition of a bedside ultrasound (US) to the evaluation process could be used to significantly reduce the number of negative x-rays in OFAR positive patients.

Methods: A prospective observational studywas conducted in a Level I urban trauma center over a 12 month period in which bedside US was utilized to detect foot and/or ankle fractures in OFAR positive patients of age 18 years and older. All patients in the study received foot and/or ankle x-rays based on OFAR exam. Prior to viewing the x-rays, trained clinicians performed bedside US targeting the medial and lateral malleoli, navicular, and base of the 5th metatarsal and provided a diagnostic impression based on their US findings. The US findings were then compared to the formal x-ray interpretation.

Results: A total of fifty patients was enrolled into the study of which twenty-one patients were discovered to have a fracture by US. The sensitivity ofUS in detecting foot and/or ankle fractures was 100% (95% Confidence Interval [CI] 78%-100%) and the specificity of OFAR increased from 50% (95% CI 37%-63%) to 100% (95% CI 87%-100%) with the addition of US. The negative predictive value was 100% (95% CI 89%-100%), and the positive predictive value was 100% (95% CI 81%-100%).

Conclusions: Among OFAR positive patients, bedside US has high sensitivity and specificity for detecting foot and/or ankle fractures. Further studies should be conducted to determine if utilizing bedside US in addition to OFAR could significantly reduce the number of x-rays and improve the efficiency and costs associated with evaluating these injuries in the ED. Implication for health policy/medical education/research/ practice. Utilizing bedside ultrasonography in addition to Ottawa Foot and Ankle Rules in acutely injured patients could significantly reduce the number of ordered x-rays and length of stay in the emergency department.