Ankle Sprain Diagnosis

  • Diagnosis

    As opposed to a strain, which is an injury to a muscle or a tendon, an ankle sprain is an injury that stretches or tears the ligaments, or fibrous bands, that support the ankle joint. The damage to the ligaments causes the joint to become inflamed, leading to swelling, pain, and sometimes bruising. In many cases, the injury also results in a temporary inability to move the ankle or to put weight on it.

    Americans experience an estimated 850,000 ankle sprains each year, making it one of the most common injuries in the US.

    Ankle sprains typically occur on uneven walking surfaces--while stepping off a curb, for example, or while strolling across a grassy lawn that has unexpected dips or holes. Making a misstep during an athletic event or while exercising can also lead to a sprain. An ankle can get sprained while a foot is firmly planted on the ground if the body gets twisted in a way that puts abnormal pressure on the ankle.

    A sprained ankle is usually the result of an inward roll (inversion) injury. Figure 01 This injury occurs when the foot is forced to "roll in" (invert), putting abnormal pressure onto the outside edge of the foot. The pressure then stretches or tears one or more of the lateral, or outside, ligaments of the joint.

    A much less common cause of a sprained ankle is an outward roll (eversion) injury. With this injury, the foot is suddenly turned outward, causing the medial, or inner ligaments of the ankle to be stretched or torn.

    An eversion injury sometimes results in what is known as a high (syndesmotic) ankle sprain. This type of sprain occurs just above the ankle joint to the ligaments between the two major lower leg bones (tibia and fibula). High ankle sprains are treated in a similar manner to other sprains, but they tend to be more severe and take longer to heal.

    This injury occurs when the foot “rolls in” (inverts), stretching or tearing one or more of the lateral, or outside, ligaments of the joint.

    Click to enlarge: Inversion injury

    Figure 01. Inversion injury

    All ankle sprains produce some level of pain at the time of the injury. The joint will also feel tender and begin to swell. If the sprain is mild, you may experience very little loss of joint function and may not fall when the injury occurs. You may also be able to walk on the injured ankle without much discomfort. The joint will probably lose some of its stability, however, and feel loose.

    Other symptoms of a sprained ankle include:

    • mild to severe pain at the time of injury
    • sometimes, a feeling of popping or tearing in the ankle at the time of injury
    • swelling and/or bruising at the injured joint
    • mild to severe loss of the ability to move or put pressure on the joint

    With a more serious sprain, you will likely fall at the time of injury. You will also find it difficult, if not impossible, to move or put weight on the injured ankle. Bruising will also appear, and swelling may spread from the ankle to the foot and perhaps to the lower calf.

    Participating in certain sports--those in which you are likely to jump and accidentally land on the side of your foot--increases your risk of spraining your ankle. These sports include basketball, tennis, skiing, soccer, volleyball, and distance and high jumping.

    Running or walking on rough, uneven surfaces also increases your risk; especially if you are wearing shoes with insufficient support to protect your ankle should you accidentally twist it.

    If you have high-arched or flat feet, you are more susceptible to ankle sprains.

    In addition, your risk of spraining your ankle increases if you have had earlier sprains or other ankle injuries that may have weakened the joint.

    Your doctor will ask you questions about your injury and your symptoms. You’ll be also be asked if you have injured your ankle in the past.

    Your doctor will examine your ankle to determine the extent of the sprain and to make sure that you haven’t fractured a bone. He or she will touch various points of your ankle and foot, and perform several tests to determine the extent of damage to your ligaments. For one of these tests, known as the anterior drawer test, your doctor will cup the heel of your injured leg in one hand and then gently pull the heel forward while holding firmly with his or her other hand to your lower shin. For another test, known as the taler tilt test, your doctor will carefully rotate your ankle outward. You’ll also be asked to put weight on your injured ankle. If you experience pain when a bony area is touched or when attempting to stand or walk, you may have a fracture.

    Children need to be examined especially carefully to make sure that their symptoms are not a result of injury to a pediatric growth plate—which can mimic symptoms of a sprained ankle. The doctor will apply pressure to the growth plate areas; if the child feels pain, the plate may be broken.

    Doctors grade sprains according to the severity of the injury.

    • Grade I sprain. This mild sprain results in a stretched or slightly torn ligament, but only slight pain or swelling. You can put weight on the joint and move it with no discomfort.
    • Grade II sprain. This moderate sprain causes partial tearing of the ligament, resulting in moderate pain and swelling and perhaps some bruising. You will have some difficulty putting weight on or moving the joint.
    • Grade III sprain. This severe sprain causes a complete rupture of the ligament. Pain, swelling, and bruising is severe. You can’t put weight on or move the joint.

    If your doctor suspects a fracture, he or she may order an x-ray of your ankle. To determine if a ligament has been completely ruptured, your doctor may also order special “stress” x-rays. These are standard x-rays that are taken while someone rotates or stresses the ligaments in the injured joint.

    In some cases--high ankle sprains, for example--doctors order computed tomographic (CT) scanning or magnetic resonance imaging (MRI). Both of these tests produce more detailed images than standard x-rays. A CT scan uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices) of the body. MRI uses a combination of large magnets, radio frequencies, and a computer to produce its images.

    You can do many things to lower your risk of spraining your ankle.

    • Wear shoes that fit properly and that provide plenty of stability
    • Avoid wearing high-heeled or platform shoes
    • Exercise on even surfaces
    • Wear a brace or have your ankle taped when participating in sports with a high incidence of ankle injuries
    • Do ankle-strengthening exercises several times a week
    • Stretch your leg muscles daily

  • Prevention and Screening

    You can do many things to lower your risk of spraining your ankle.

    • Wear shoes that fit properly and that provide plenty of stability
    • Avoid wearing high-heeled or platform shoes
    • Exercise on even surfaces
    • Wear a brace or have your ankle taped when participating in sports with a high incidence of ankle injuries
    • Do ankle-strengthening exercises several times a week
    • Stretch your leg muscles daily

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