 Introduction/Background Ankle injuries are the most common injury presenting to primary care and emergency rooms [1,2], accounting for 4.4% of United States emergency room visits [3]. Acute ankle sprains (pain, swelling, limited mobility) make up the majority of these injuries, with an estimated incidence of 2 million per year [4]. Diagnosis of presence and degree of sprain, fracture, subluxation, dislocation, cartilage abnormalities, foreign bodies, or neurovascular involvement are critical in determining appropriate and timely orthopedic fixation/treatment planning [1,5] and to avoid chronic pain and immobility. Appropriate use of ankle imaging guidelines and clinical decision support mechanisms is paramount [6,7]. The current standard clinical imaging guidelines to determine if radiographs are necessary are the Ottawa Ankle Rules (OAR), instituted in 1992. The OAR have been validated for adults and children >5 years of age [8] and recommend ankle radiographs in patients with the following clinical criteria in the acute setting: 1) inability to bear weight, 2) point tenderness over the medial malleolus, the posterior edge or inferior tip of the lateral malleolus, talus, or calcaneus, or 3) inability to ambulate for 4 steps. For the purposes of this paper, the OAR will still apply during the first 1- to 3-week interval following initial injury. Multiple validation studies have confirmed OAR effectiveness and utility in obtaining appropriate imaging, reducing unnecessary radiographs and costs, and improving clinical outcomes [8-13]. Exclusionary Criteria OAR should not be used in children <5 years of age or in those patients with a neurologic abnormality affecting the lower leg with decreased sensation (eg, diabetic), altered sensorium, or inability to communicate [8,25,26]. Other The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels.
Acute Trauma to the Ankle.  Introduction/Background Ankle injuries are the most common injury presenting to primary care and emergency rooms [1,2], accounting for 4.4% of United States emergency room visits [3]. Acute ankle sprains (pain, swelling, limited mobility) make up the majority of these injuries, with an estimated incidence of 2 million per year [4]. Diagnosis of presence and degree of sprain, fracture, subluxation, dislocation, cartilage abnormalities, foreign bodies, or neurovascular involvement are critical in determining appropriate and timely orthopedic fixation/treatment planning [1,5] and to avoid chronic pain and immobility. Appropriate use of ankle imaging guidelines and clinical decision support mechanisms is paramount [6,7]. The current standard clinical imaging guidelines to determine if radiographs are necessary are the Ottawa Ankle Rules (OAR), instituted in 1992. The OAR have been validated for adults and children >5 years of age [8] and recommend ankle radiographs in patients with the following clinical criteria in the acute setting: 1) inability to bear weight, 2) point tenderness over the medial malleolus, the posterior edge or inferior tip of the lateral malleolus, talus, or calcaneus, or 3) inability to ambulate for 4 steps. For the purposes of this paper, the OAR will still apply during the first 1- to 3-week interval following initial injury. Multiple validation studies have confirmed OAR effectiveness and utility in obtaining appropriate imaging, reducing unnecessary radiographs and costs, and improving clinical outcomes [8-13]. Exclusionary Criteria OAR should not be used in children <5 years of age or in those patients with a neurologic abnormality affecting the lower leg with decreased sensation (eg, diabetic), altered sensorium, or inability to communicate [8,25,26]. Other The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels.