An ankle sprain occurs when the strong ligaments that support the ankle stretch beyond their limits and tear. Ankle sprains are common injuries that occur among people of all ages. They range from mild to severe, depending upon how much damage there is to the ligaments.
Most sprains are minor injuries that heal with home treatments like rest and applying ice. However, if your ankle is very swollen and painful to walk on — or if you are having trouble putting weight on your ankle at all, be sure to see your doctor.
Without proper treatment and rehabilitation, a more severe sprain can weaken your ankle—making it more likely that you will injure it again. Repeated ankle sprains can lead to long-term problems, including chronic ankle pain, arthritis, and ongoing instability.
Ligaments are strong, fibrous tissues that connect bones to other bones. The ligaments in the ankle help to keep the bones in proper position and stabilize the joint.
Most sprained ankles occur in the lateral ligaments on the outside of the ankle. Sprains can range from tiny tears in the fibers that make up the ligament to complete tears through the tissue.
If there is a complete tear of the ligaments, the ankle may become unstable after the initial injury phase passes. Over time, this instability can result in damage to the bones and cartilage of the ankle joint.
Your foot can twist unexpectedly during many different activities, such as:
A sprained ankle is painful. Other symptoms may include:
If there is severe tearing of the ligaments, you might also hear or feel a “pop” when the sprain occurs. Symptoms of a severe sprain are similar to those of a broken bone and require prompt medical evaluation.
Your doctor will diagnose your ankle sprain by performing a careful examination of your foot and ankle. This physical exam may be painful.
If there is no broken bone, your doctor may be able to tell the severity of your ankle sprain based upon the amount of swelling, pain, and bruising.
X-rays. X-rays provide images of dense structures, such as bone. Your doctor may order x-rays to rule out a broken bone in your ankle or foot. A broken bone can cause similar symptoms of pain and swelling.
Stress x-rays. In addition to plain x-rays, your doctor may also order stress x-rays. These scans are taken while the ankle is being pushed in different directions. Stress x-rays help to show whether the ankle is moving abnormally because of injured ligaments.
Magnetic resonance imaging (MRI) scan. Your doctor may order an MRI if he or she suspects a very severe injury to the ligaments, damage to the cartilage or bone of the joint surface, a small bone chip, or another problem. The MRI may not be ordered until after the period of swelling and bruising resolves.
Ultrasound. This imaging scan allows your doctor to observe the ligament directly while he or she moves your ankle. This helps your doctor to determine how much stability the ligament provides.
After the examination, your doctor will determine the grade of your sprain to help develop a treatment plan. Sprains are graded based on how much damage has occurred to the ligaments.