Anatomy:
1. Anterior talofibular ligament - ATFL:
Anterior aspect of lateral malleolus to talar neck
Just anterior to fibular articular surface.
Best seen on axial MR - thin band between lateral malleolus and talar body
May be bifasciculated or striated
Thinnest and weakest of 3 ligaments
2. Calcaneofibular ligament - CFL:
2nd common ligament to be injured
Associated with ATFL injury, subtalar injury, sinus tarsi ligament injury
Isolated tears are rare
Between tip of lateral malleolus to small tubercle on lateral aspect of the calcaneus
Seen on coronal and axial
Deep to peroneal tendons
May be seen incompletely
Stabilizes talotibial and subtalar joints
2 cm long, 4-6 mm thick
Secondary to twisting injuries in dorsiflexion and internal rotation
3. Posterior talofibular ligament - PTFL:
Broad, fan-shaped origin from fibular fossa of distal fibula to posterior aspect of distal tibia
Strongest
Seen on axial and coronal images
Appears striated (interspersed fat)
May show heterogeneity and thickening
Important and Common things about lateral ligament complex injuries:
Most of ankle ligament injuries occur here (85%)
Frequently associated with capsule rupture and joint fluid extravasation
Epidemiology:
15-35 years
Male more than female (after 40 more common in female)
Mechanism:
Inversion, internal rotation, planatar flexion
Most involve long axis of the ligament
Clinical features:
Pop feeling, pain, swelling, difficulty in weight bearing, sense of giving away
Anterior drawer test, inversion stress test are positive
Grading:
1: stretched ATFL
2: Partial ATFL tear, stretched CFL
3: Complete ATFL and CFL tears
Degree:
ATFL is weakest and hence first torn, followed by CFL and PTFL
1st degree: partial or complete tear of the ATFL
2nd degree: partial or complete tear of the ATFL and CFL
3rd degree: injury to ATFL, CFL and PTFL
Optimizing MR:
ATFL best seen on axial
3D axials might be used
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MR features:
Discontinuity (complete or incomplete), Detachment, Avulsion, Thickening, Thinning, Irregularity
Signal change in the ligament - int signal on T1 or PD, and increased signal on FST2
Signal change around ligament - fluid or haemorrhage
Obliteration of fat planes around ligament, joint fluid extravasation
Thickening or abscence of ATFL
Distal fibular avulsion
Capsular rupture
Synovitis
Anterolateral gutter soft tissue oedema
Marrow edema at insertion of the ligaments
Fluid in the peroneal tendon sheath (CFL tears)
Bone bruises in medial or lateral talus or calcaneus
Morphological abnormality without soft tissue and bone changes in chronic tears - may show reduced signal in surrounding fat due to scarring or synovial proliferation
Acute tear:
Haemorrhage/ hemosiderin
Hyperplastic synovial reaction
Chronic tear:
Meniscoid lesion
Generalised thickening of ligament
CFL tear:
Most common in midsubstance
Best seen on coronal and axial
Partial or complete inturruption
Laxity
Irregularity
Haemorrhage
Focal edema
Widening of lateral joint place (when a/w ATFL injury)
Peroneal retinacular thickening
Tenosynovitis of the peroneals
Peroneal subluxation
Peroneal tear
