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What Is an Ankle Sprain?

A sprain is a medical term for an injured ligament. Ligaments are fibrous bands of tissue that connect bones to each other (as opposed to tendons, which connect bones and muscles). The ankle is one of the most often sprained parts of the body, with more than 20,000 occurring in the United States every day.

There are eight ligaments at the ankle joint, but the most commonly sprained are the three that make up the lateral ligament complex, which can be found on the outside of the ankle. These ligaments connect the fibula (calf bone) to bones in the foot—namely the talus, which sits beneath the tibia (shin bone) and fibula, and calcaneus (heel bone).

Causes and Risk Factors

The reason the ligaments of the lateral ligament complex are sprained so often is because these are the ligaments that get damaged when people “roll” their ankles. These ligaments keep the ankle stable and prevent it from moving from side-to-side. Rolling the ankle—a movement that causes the outside of the foot to point toward the ground—causes damage to these ligaments because it is a motion that these ligaments are supposed to prevent.

Ankle sprains happen often while exercising or playing sports, but they can happen in other ways as well, including:

  • During a fall
  • Missing a step on the stairs
  • Walking on an uneven surface


Pain is the main symptom of an ankle sprain. A severe sprain might be accompanied by a popping sound or sensation. Other symptoms include:

  • Ankle instability
  • Bruising
  • Swelling
  • Tenderness

Spraining an ankle once increases the risk of future sprains because the ligaments loosen and become damaged. As a result, they are not as effective in keeping the ankle in place and preventing excessive movement. This is known as chronic ankle instability.


Diagnosis generally starts with a physical exam and medical history. A doctor will gently manipulate the foot and ankle while looking for ankle sprain symptoms and signs of pain. The medical history may reveal an acute event that caused the pain.

Often, a physical exam and medical history are all that is necessary to diagnose an ankle sprain. When the diagnosis is not clear, an X-ray may be ordered to rule out a broken bone. A magnetic resonance imaging (MRI) scan can detect damage to the ligament in the case of an ankle sprain. It may also reveal damage to cartilage or other soft tissue that might be causing pain instead or in addition.


When an ankle injury happens, it is important to employ the R.I.C.E. protocol (rest, ice, compression, elevation) as soon as possible to minimize further damage to and swelling of the joint.

Most ankle sprains, even when the ligament is torn in two, can be treated without surgery. The first step in treatment is resting the joint and immobilizing the ankle so it is able to heal. This may be done with a brace or a boot.

Physical therapy (PT) is usually the next mode of treatment. PT is centered initially around restoring strength and range of motion to the ligaments, tendons and muscles that make up the ankle joint. Once the joint is recovering, exercises will be introduced that are designed to further strengthen the ankle and prevent a recurrence of a sprain.


Ankle sprains are graded from one to three, mild to severe. A grade I sprain may heal in as little as two weeks. A grade III sprain, when the ligament is completely torn, may take up to 12 weeks or longer to heal. Most ankle sprains will heal fully when given enough time, allowing the person to resume their day-to-day activities—even sports that require sudden changes of direction.

If you are experiencing ankle pain and you believe you may have sprained your ankle, schedule an appointment with one of our foot and ankle specialists to discuss your diagnosis and treatment options.

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