The Ottawa Ankle Rule (OAR), developed in the early 1990s, is a widely validated clinical decision-making tool that helps clinicians determine when radiographs are necessary in patients presenting with acute ankle or foot injuries. The rule was introduced to address the common problem of excessive imaging in emergency departments, where most patients with ankle injuries do not actually have fractures. By applying simple physical exam criteria, the OAR provides a safe, evidence-based method to minimize unnecessary radiation exposure, reduce healthcare costs, and improve efficiency in patient care.

The tool applies to patients with ankle pain after blunt trauma and uses specific findings to guide imaging decisions. For the ankle, the rule focuses on tenderness at the posterior edge or tip of the lateral or medial malleolus and the patient’s ability to bear weight both immediately after injury and during examination. For the foot, it considers tenderness at the base of the fifth metatarsal or the navicular bone, along with weight-bearing capacity.

Multiple studies and meta-analyses have confirmed the high sensitivity (nearly 100%) of the Ottawa Ankle Rule for detecting clinically significant fractures, meaning it is highly unlikely to miss a fracture when applied correctly. Specificity is moderate, which means some unnecessary X-rays may still be ordered, but overall the tool significantly reduces imaging rates.