An ankle sprain is an injury caused by stretching and tearing one or more ligaments that support the ankle. Ligaments are strong, flexible stretches of fiber that hold bones and other anatomy together.
Ligaments usually connect one bone to another, keeping the ankle strong and intact. The ankle has several ligaments. The most important ligaments in the ankle are the anterior talofibular ligament (ATFL) and the calcaneal fibular ligament (CFL). The ligaments on the outside of the ankle (also called lateral), such as the ATFL and CFL, are injured most often. Another large ligament (the posterior talofibular, or PTFL) runs along the back (posterior) of the ankle, but is not injured as often as the ATFL and CFL. Most ankle sprains occur from a force that twists the foot or lower leg and injures the outside ligaments. The severity of an ankle sprain depends on the force that causes it, along with whether the ligament is only stretched, partially torn, or completely torn.
Mechanical forces cause ankle sprains, so people who participate in sports that involve landing on and twisting of the ankle can be at higher risk. Other risks involve poor conditioning, which makes the ligaments and muscles weaker, and obesity, which places more stress on the joints. Having a past ankle sprain also increases risk, especially if ankle movement and strength do not recover fully.
Although participating in sports increases risk, some are more likely to cause an ankle sprain. Basketball players quickly change from one direction to another, and their foot can twist or roll when they cut, come down from a jump, or have their ankle stepped on by another player. Even running can cause an ankle injury, especially when running along trails or other uneven surfaces. Other sports that can cause ankle sprains are tennis, soccer, and football. Anyone can sprain an ankle if walking on an uneven surface that can cause the ankle to roll or twist awkwardly. Ankle sprains also are caused by falls.
Symptoms of an ankle sprain include:
Diagnosis of an ankle sprain begins with a doctor's examination of signs and symptoms. The doctor might order imaging tests to make sure the ankle is not broken.
During the examination, the doctor asks about the cause of the injury and then physically examines the ankle and foot. Pressing gently around the ankle joint can show which ligaments are affected by swelling, pain, tenderness in the area, etc.. The doctor also might gently move the ankle to check to see if it goes in different directions or is too stiff and swollen to move.
The most common test used in examining ankle sprains is an ankle radiograph (x-ray). The doctor typically orders the imaging only when signs of injury meet certain criteria. The patient might sit or lie on a table in the radiography room, and a technologist will position the ankle to capture images of the portion of the ankle that is injured; this might require taking images from a few different positions. Radiographs are best at showing bone and can help ensure that there are no bone fractures as part of the injury. Magnetic resonance imaging (MRI) can show detailed images of ligaments when a doctor needs to see the specific site or severity of ankle sprain. MRI uses a magnet and computer software to display images on a computer monitor. In serious or complex injuries, a computed tomography (CT) scan of the ankle can show the injury in three dimensions.
If an ankle injury is severe enough to require surgery, doctors might first perform ankle arthrography to look for specific damage. Doctors take moving radiographs (fluoroscopy) of the ankle after injecting a special dye into the joint or bloodstream to help highlight structures. Sometimes, a doctor uses ultrasound, which is imaging with high-frequency sound waves, to view the affected ligament while it is being moved to determine whether it is stable.
Treatment for ankle sprains is based on a grading scale of severity:
Often, an ankle sprain is kept immobile during early treatment. Special braces made of plastic and sometimes inflated with air can provide stability. The support devices, along with taping, help keep the ankle stable when a person begins to put weight on it, improving healing. Appropriate and gradual movement is important to treating a sprained ankle, and some patients receive physical therapy to help them improve strength and mobility. The need for physical therapy depends on the type or grade of injury.
Controlling pain from an ankle sprain makes a person more comfortable and able to begin light use of the joint. The only medication usually necessary is an over-the-counter pain reliever, such as ibuprofen or acetaminophen. These drugs, also called nonsteroidal anti-inflammatory drugs, also can ease initial swelling.
Some herbs or supplements are said to relieve swelling and pain. For example, vitamin C and beta-carotene can reduce pain, and both nutrients contribute to the body's creation of connective tissue such as ligaments. Zinc is said to speed healing. A person using alternative therapies should check with a doctor to be sure the supplements do not interact with current medications.
It is essential to rest an ankle that is sprained and to reduce early swelling. The rest, ice, compression, and elevation (R.I.C.E.) technique is part of early home treatment of ankle sprains. Resting prevents additional or worsened injury, and ice and elevation help decrease swelling. Compression also helps reduce swelling and hold ice in place. Ice should not be placed directly on the skin.
Ankle sprains can cause future problems and repeat strains in the joint. At least 40% of sprains cause symptoms again after six months. A small percentage (up to 20%) of ankle sprains cause ongoing pain, instability, and other problems.
Training, conditioning, and adequate warm-up before participating in a sport with high risk for ankle sprain can help prevent the injury. Wearing shoes that are good quality and appropriate for an activity also can prevent strains. People who have past ankle sprains often continue to wear supportive braces, tape, or high-top shoes to keep the ankle stable and prevent further injuries.
Sharp, Bob. Ankle Sprains and Associated Injuries. New York: OxMed, 2014.
Doherty, C., et al. “The Incidence and Prevalence of Ankle Sprain Injury: A Systematic Review and Meta-Analysis of Prospective Epidemiological Studies.” Sports Medicine 44, no. 1 (January 2014): 123–40.
Haddad, Steven L. “Sprained Ankle.” American Academy of Orthopaedic Surgeons. http://orthoinfo.aaos.org/topic.cfm?topic=a00150 (accessed February 25, 2017).
American College of Foot and Ankle Surgeons. “Ankle Sprain.” FootHealthFacts.org . https://www.foothealthfacts.org/conditions/ankle-sprain (accessed February 25, 2017).
Foot Care MD. “Ankle Sprain.” American Orthopaedic Foot and Ankle Society. (accessed February 25, 2017).
Ma, Benjamin C. “Ankle Sprain Aftercare.” MedlinePlus. https://medlineplus.gov/ency/patientinstructions/000574.htm (accessed February 25, 2017).
Preidt, Robert. “Study Casts Doubt on Need for Physical Therapy After Ankle Sprain.” HealthDay. https://consumer.healthday.com/bone-and-joint-information-4/sprains-health-news-635/study-casts-doubt-on-need-for-physical-therapy-after-ankle-sprain-716876.html (accessed February 25, 2017).
Young, Craig C. “Ankle Sprain Treatment and Management.” Medscape. http://emedicine.medscape.com/article/1907229-treatment#d16 (accessed February 25, 2017).
American College of Sports Medicine (ACSM), 401 W. Michigan St., Indianapolis, IN, 46202-3233, (317) 6379200, Fax: (317) 634-7817, http://www.acsm.org .
American Physical Therapy Association, 1111 North Fairfax St., Alexandria, VA, 22314-1488, (703) 684-2782, (800) 999-2782, Fax: (703) 684-7343, https://www.apst.org .
Teresa G. Odle, B.A., ELS