Friday, October 24, 2008

Ankle Sprains and the ATFL

Ankle sprains are extremely common injuries, and occur in a wide variety of sports:

The anterior talofibular ligament (ATFL) is a major component of the lateral collateral ligament complex of the ankle joint and plays an important role in stabilizing the ankle. The ATFL is the most frequently torn ligament in ankle sprains.

The ATFL is usually thought of as a single structure, but the ATFL can have more than one band (Milner and Soames;J. Anat 191, 457-458, 1997). These investigators carefully dissected 26 cadaver ankles. In 38% of ankles, the ATFL had a single band; in 50% of ankles, the ATFL had two bands, and in 12% of ankles, the ATFL had three bands. The overall width of the ATFL did not vary greatly, irrespective of the number of bands present.

This variation in structure can be seen on MRI as well. In the following patient, the ATFL has a single band:

In this ankle, the ATFL has two bands:

In the final example, we see an ATFL composed of three bands:

The individual bands of the ATFL are best perceived on coronal images. Thus, do not confuse variations in the fascicular structure of the ATFL for a tear of this ligament.

Vic David MD

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