Ottawa Ankle Rules
Acute ankle sprains
– Common complaint in ED
– Ankle and C-spine radiographic series are the two most commonly ordered musculoskeletal x-rays in ED
– Approx 5 million ankle x-rays in Canada and US
Estimated $500 million in professional and technical cost of performing X-Rays. There is no widely accepted guidelines for the use of radiography in the ankle injuries.
Purpose of Ottawa Rules
Decision rules used to determine if radiographs are indicated in foot ankle/foot. Develop decision rules that are 100% sensitive for detecting clinically significant fractures of the ankle and midfoot
Zones of Ankle
– Malleolar zone- distal 6cm of tibia and fibula and talus
– Midfoot zone- navicular, cuboid, cuneiforms, anterior process of calcaneus, and base of the 5th metatarsal
Goal: to develop decision rules that were 100% for detecting clinically significant fractures on each the ankle injury patients. Conducted using 21 ED physicians at 2 Ottawa hospitals.
– 750 pts presenting with acute blunt injuries to ankle (twisting injuries, falls from height etc)
32 Predictor variables were assessed using kappa coefficient for Ankle and Foot Fx’s.
– specific points of tenderness
– ability to bear weight for at least 4 steps
Estimate the probable fracture under x-ray.
-ankle and midfoot zones
- Body and tuberosity of calcaneus
- Less than 18 years of age
- Dermatological injuries
- Radiographs from osh
Conclusion: Insignificant Variables
- Mechanisms of injury (get more info)
- “cracking sound”
- Drawer sign
- Soft tissue tenderness
- Proximal fibular tenderness
First Part Results
Physicians would’ve missed 29% of fractures on the ankle series if the cutoff point for ordering radiographs had been their own predictive probability of 50% for a fracture. Two decision rules derived by multivariate recursive partitioning techniques that would’ve identified 100% of the fractures.
Decision Rule #1
Ankle radiographic series was only necessary if the pt had pain near the malleoli and one or more of these findings.
- Age 55 or greater
- Inability to bear weight immediately after the injury and for four steps in the emergency department or
- Bone tenderness at the navicular bone, the cuboid, or the base of the 5th metatarsal
Decision Rule #2
Foot radiographic series was only necessary if the pt had pain in the midfoot and bone tenderness at the navicular bone, the cuboid, or at the base of the 5th metatarsal.
Part II “refinement and Prospective Validation”
1052 pts; Refinement of original rules
– Univariate and recursive partitioning analyses
Prospective Validation of Original Rules
- all 121 malleolar zone fxs were identified by the ankle decision rules – sensitivity of 1.0
- Foot decision rules 48/49 midfoot fractures
Validation of Refined Decision Rules
- 453 pts
- Identified all 50 ankle series fractures – sensitivity of 1.0
- Sensitivity of Ottawa ankle rules for fracture=1.0
- CI= 95%
- Inability to bear weight – Most reliable Variable
Implications of Ottawa Rules
- 30% decrease in ankle and foot X-rays
- Decreased waiting times for patients to be discharged
Stiel IG, Greenberg, Gary H, et al. Decision Rules for the use of Radiography in Acute Ankle Injuries: Refinement and Prospective Validation. JAMA. 1993; 269:1127-1132
Stiel et al. Use of Radiography in Ankle Injuries. Ann Emerg Med. April 1992;21;384- 390
Heyworth J. Ottawa Ankle Rules for the Injured Ankle. BMJ.2003; 326:405-6
Bachman, LM, Kold E, et al. Accuracy of Ottawa Ankle Rules to Exclude Fracture of the Ankle and Mid-foot: Systemoc Review