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Broken Ankle or Ankle Sprain?

Medical Author: Benjamin C. Wedro, MD, FACEP, FAAEM
Medical Editor: Charles P. Davis, MD, PhD

When an X-ray is needed to diagnose a sprained or broken ankle

The difference between doctors who look after mere mortals and those who look after elite athletes may have to do with how many tests they can order, regardless of the cost. And when X-ray and MRI reports lead the news, it makes it difficult for family doctors to explain why those tests aren't necessarily appropriate for them (or even the elite athlete).

Ankle sprains are common injuries and historically, patients expected that if they went to the ER or their doctor's office, they would have an X-ray taken to prove there were no broken bones. As it turns out, the vast majority of those ankle X-rays done were normal and, in retrospect, could be seen as expensive, wasteful, and posed another opportunity to expose a person to unneeded radiation. Ian Stiell and his colleagues in Ottawa, Canada completed a study that showed it was not useful to order all those tests, since less than 15% of those ankle X-rays were positive for a fracture. The results of the study also allowed Dr. Stiell to develop the Ottawa ankle rule guidelines. They give the doctor and the patient a starting point for the discussion about care and treatment for ankle injuries.

Following the Ottawa ankle rules, X-rays are only needed when these criteria are present:

  • Tenderness over the tip of the lateral malleolus (the fibula bone on the outside of the ankle) and the last 2.5 inches (or 6 cm) of the bone
  • Tenderness of the tip of the medial malleolus( the tibia bone on the inside of the ankle) and the last 2.5 inches of the bone
  • Tenderness over the navicular, a bone in the instep, or of the fifth metatarsal base, the bony prominence on the outside of the foot
  • Inability to weight bear for 4 steps immediately or in the ER/office

Ankle sprains and other injuries

Just because an ankle isn't broken doesn't mean that no injury has occurred. An ankle sprain means that the ligaments that keep the ankle stable have been stretched or torn. Sometimes a torn ankle ligament is just as important as a broken bone, especially if it is the deltoid ligament on the medical or inner aspect of the ankle. That ligament is all that keeps the ankle from dislocating and may be injured in association with a fractured lateral malleolus (with this injury, there is always significant swelling and pain that would fit the criteria to require an X-ray). Some patients do not fit into the Ottawa ankle rules such as children under 6, pregnant women, or someone unable to respond to appropriate questions.

Initial treatment for a sprained ankle starts with RICE (rest, ice, elevation and compression), and anti-inflammatories such as ibuprofen or naproxen. Ace bandages help with compression and aircasts or active ankle brace, worn inside the shoe in addition to the ace wrap may help with ankle support. Crutches may be used for walking support especially if there is difficulty walking without pain or a limp.

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