Anterior talofibular ligament injury

Anterior talofibular ligament (ATFL) injury is the most common of the ligament injuries that can occur as part of the lateral ligament complex injuries 2. The injuries can comprise of either soft tissue tears, avulsion fractures or both.

ATFL injuries typically occurs with an inversion +/- plantar flexion injury to the ankle. Approximately two-thirds of ankle sprains tend to be isolated injuries to the ATFL (the ATFL is the weakest ligament in lateral collateral complex of the ankle). There is general agreement that avulsion is more common at the fibular than the talar end of the ligament 2.

Grading

The severity of ligamentous injury can be classified into 3 tiers (ref required):

  • grade I: injury without macroscopic tears
  • grade II
    • partial tear
    • mild to moderate joint instability may be present
  • grade III
    • complete tear
    • inability to weight-bear
    • associated with significant joint instability
Plain radiograph/CT

Many show an associated avulsion fracture at either the fibular end or less commonly the talar end.

May show ancillary features such as an ankle joint effusion and/or overlying lateral malleolar soft tissue swelling.

Ultrasound

Has been shown to have high sensitivity and specificity rates for chronic ATFL tears 6.

MRI

Both the anterior and posterior talofibular ligaments are usually seen on a single axial image obtained slightly distal to the tibiofibular ligaments 4.

MRI may show discontinuity, detachment, thickening, thinning, irregularity of the ligament, a bright rim sign 5 or an associate bony avulsion. Heterogeneity with increased intraligamentous signal intensity on fat-suppressed or T2-weighted images is indicative of intrasubstance oedema or haemorrhage.

  • T2
    • fluid within the joint serves to highlight the anterior talofibular ligament on T2-weighted images
    • the ligament appears as a thin, straight, low signal intensity band extending from the talus to the fibular malleolus
    • a bright rim sign (cortical defect with a bright dot-like or curvilinear high signal intensity lesion) may be seen on T2 weighted imaging

On MRI consider:

  • anterolateral impingement syndrome of ankle 4
    • repetitive synovial inflammation secondary to chronic lateral ankle instability produces a soft-tissue “mass” consisting of hypertrophic synovial tissue and fibrosis within the lateral gutter
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Article Information

rID: 24471
Section: Pathology
Synonyms or Alternate Spellings:
  • ATFL injury
  • Anterior talofibular ligament injuries
  • Anterior talofibular ligament (ATFL) injury
  • ATFL injuries

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Cases and Figures

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    Case 1: torn ATFL
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    Case 2: chronic injury ATFL
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    Case 3: chronic injury ATFL
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    Case 4: with avulsion fragment off talus
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    Case 5: torn ATFL with soft-tissue impingement
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    Bilateral anterio...
    Case 6
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    Case 7: torn ATFL
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    Case 8
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    Case 9
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    Case 10: chronic injury with anterior talar shift
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