Mild sprains and strains can often be treated at home, while severe ones may require some form of immobilization, or even surgery to repair the injured structures.

The diagnostic process for an ankle strain or sprain usually involves a physical exam and grading according to severity.

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Ankle sprain and strain severity grading

Doctors usually follow a three-step grading system when diagnosing sprains and strains:

    Grade 1
    In Grade 1 ankle sprains and strains, there is minimal tearing of the affected ligaments or muscles/tendons. The injury is primarily an overstretch, and any tearing that exists is on a microscopic level. Tenderness, pain, and swelling of the injury site is minimal, but still enough to be noticed upon viewing or palpating (touching). Slight bruising or discoloration of the skin may be present, and standing/walking impairment is also minimal.

    Grade 2
    In Grade 2 ankle sprains and strains, there is moderate tearing of the affected ligaments or muscles/tendons. In moderate tearing, some individual ligament or muscle/tendon fibers may be torn completely, but there are still enough other fibers intact for the tissue to retain its integrity overall. Swelling, pain, and tenderness at the injury site are moderate, though there may be some loss of range of motion. Some patients with Grade 2 sprains and strains may have some ankle instability, such as having the ankle partially give way with standing or walking. Moderate bruising or skin discoloration may be present, and the patient may have some trouble walking or standing.

    Grade 3
    In Grade 3 ankle sprains and strains, there is a complete tearing or rupturing of the affected ligaments or muscles/tendons, with no individual fibers remaining intact. Swelling and tenderness at the injury site is significant, and often includes severe discoloration of the skin (black-and-blue, purplish-black). The ankle cannot support any weight whatsoever, and there is little to no remaining range of motion. Standing, walking, or turning of the foot is impossible.

Regardless of the injury's apparent severity, people who suspect they have an ankle sprain or strain are advised to seek appropriate medical attention as soon as possible to receive the correct diagnosis and treatment. Delaying treatment can sometimes make an ankle injury worse.

What to expect in an ankle sprain or strain examination

When diagnosing a sprain or strain and grading its severity, doctors will usually do one or more of the following:

  1. Inspect the affected ankle visually to discern the level of swelling and bruising.
  2. Palpate the injury site to gauge tenderness and swelling levels.
  3. Rotate, flex, or extend the foot and ankle to test range of motion and determine which tissue(s) is injured. This activity may be quite painful, especially for patients with Grade 2 or 3 sprains and strains.
  4. Order diagnostic testing, such as X-ray or magnetic resonance imaging (MRI) to determine exactly which tissues are injured and where, as well as to rule out possible bone fracture, bone chips, or other concurrent joint-surface injuries. In some cases, MRI may need to be delayed until after the initial swelling and bruising subsides.1,3

While ankle sprains and strains have similar symptoms and similar treatments, it is important that the correct diagnosis be made so the appropriate treatment protocol can be administered, especially in the case of severe or chronic injuries that may require surgery.

References:

  1. American Academy of Orthopedic Surgeons, and American Orthopedic Foot and Ankle Society. Sprained ankle. OrthoInfo: September 2012. http://orthoinfo.aaos.org/topic.cfm?topic=A00150. Accessed November 17, 2014.
  1. Sutton T. Sprain vs. strain. Hughston Health Alerts. Auburn, AL: The Hughston Foundation. http://www.hughston.com/hha/a.strain-sprain.htm. Accessed November 19, 2014.
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