Guidelines Summary
Ottawa Ankle Rules for Ankle Injury Radiography
An ankle x-ray series is required only if there is any pain in the malleolar zone along with any of these findings [16] :
-
Bone tenderness at the posterior edge or tip of the lateral malleolus
-
Bone tenderness at the posterior edge or tip of the medial malleolus
-
Inability to take 4 complete steps both immediately and in the emergency department (ED)
A foot x-ray series is required only if there is any pain in the midfoot zone along with any of these findings:
-
Bone tenderness at the base of the fifth metatarsal
-
Bone tenderness at the navicular
-
Inability to take 4 complete steps both immediately and in the ED
Apply the Ottawa Ankle Rules (OAR) accurately:
-
Palpate the entire distal 6 cm of the fibula and tibia
-
Do not neglect the importance of medial malleolar tenderness
-
Do not use for patients younger than 18 years
Clinical judgment should prevail over these rules in the following circumstances:
-
Patient is intoxicated or uncooperative
-
Patient has other distracting painful injuries
-
Patient has diminished sensation in the legs
-
Patient has gross swelling that prevents palpation of malleolar bone tenderness
Give written instructions and encourage follow-up in 5-7 days if pain and ability to walk are not improved.
Diagnostic accuracy of Ottawa Ankle Rules
The OAR were developed to predict the need for radiographs in patients with acute ankle injuries. The goal is to avoid unnecessary radiation exposure for these patients.
In a prospective study of 403 acute nonpenetrating ankle injuries, the OAR had high sensitivity (95-100%) and negative predictive value (100%) but low specificity (40-51%) and positive predictive value (24-28%). [17] A meta-analysis showed that the OAR can accurately predict ankle fractures when they are present (before radiographic confirmation), with a high sensitivity of 91%; however, the lower specificity of 25% increases the likelihood of false-positive results. [18]
-
Diagram showing the typical locations for ankle fractures occurring from the 4 major injury mechanisms (SA= supination adduction, SE= supination external rotation, PA= pronation abduction, PE= pronation external rotation). Note that the SE fracture is shown as a dashed line, since it is best seen in the lateral projection.
