American Board of Internal Medicine (ABIM) Certification Practice Exam

What criteria warrant obtaining radiographs according to the Ottawa ankle and foot rules?

1. Inability to walk four steps after an injury

2. Single malleolus tenderness

3. Presence of swelling without pain

4. Prolonged rest with no improvement

The correct answer is: Inability to walk four steps after an injury

The criteria for obtaining radiographs based on the Ottawa ankle and foot rules are designed to identify patients who may have a significant fracture that requires imaging. Inability to walk four steps after an injury is a specific indicator that suggests a potential fracture in the ankle or foot. This criterion is based on the premise that if a patient is unable to bear weight immediately after the injury and during the examination, there may be a serious underlying injury. This decision is driven by the rationale that the inability to walk indicates significant pain or dysfunction, which warrants further investigation through radiographs to ensure that fractures are not missed. The Ottawa ankle rules help clinicians efficiently decide when imaging is necessary, thereby avoiding unnecessary radiographs in cases where the risk of fracture is low. The other options do not meet the established criteria for obtaining imaging. Single malleolus tenderness alone does not specify which type of injury is present or if it's significant enough to warrant an X-ray. Similarly, the presence of swelling without pain does not indicate a fracture on its own and might be related to a sprain or soft tissue injury. Lastly, prolonged rest with no improvement is too vague as it does not directly correlate with immediate post-injury assessment or the acute setting for which the Ottawa rules are intended.