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.
The severity of ligamentous injury can be classified into 3 tiers (ref required):
- grade I: injury without macroscopic tears
- partial tear
- mild to moderate joint instability may be present
- complete tear
- inability to weight-bear
- associated with significant joint instability
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.
Has been shown to have high sensitivity and specificity rates for chronic ATFL tears 6.
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.
- 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
- 1. Haraguchi N, Toga H, Shiba N et-al. Avulsion fracture of the lateral ankle ligament complex in severe inversion injury: incidence and clinical outcome. Am J Sports Med. 2007;35 (7): 1144-52. doi:10.1177/0363546507299531 - Pubmed citation
- 2. Kumai T, Takakura Y, Rufai A et-al. The functional anatomy of the human anterior talofibular ligament in relation to ankle sprains. J. Anat. 2002;200 (5): 457-65. Free text at pubmed - Pubmed citation
- 3. Noh JH, Yang BG, Yi SR et-al. Outcome of the functional treatment of first-time ankle inversion injury. J Orthop Sci. 2010;15 (4): 524-30. doi:10.1007/s00776-010-1481-1 - Pubmed citation
- 4. Rosenberg ZS, Beltran J, Bencardino JT. From the RSNA Refresher Courses. Radiological Society of North America. MR imaging of the ankle and foot. Radiographics. 2000;20 Spec No (suppl 1): S153-79. Radiographics (full text) - Pubmed citation
- 5. Lee MH, Cha JG, Lee YK et-al. The bright rim sign on MRI for anterior talofibular ligament injury with arthroscopic correlation. AJR Am J Roentgenol. 2012;198 (4): 885-90. doi:10.2214/AJR.11.6868 - Pubmed citation
- 6. Hua Y, Yang Y, Chen S et-al. Ultrasound examination for the diagnosis of chronic anterior talofibular ligament injury. Acta Radiol. 2013;53 (10): 1142-5. doi:10.1258/ar.2012.120171 - Pubmed citation
- 7. Oae K, Takao M, Uchio Y et-al. Evaluation of anterior talofibular ligament injury with stress radiography, ultrasonography and MR imaging. Skeletal Radiol. 2010;39 (1): 41-7. doi:10.1007/s00256-009-0767-x - Pubmed citation