Presentation
Twisting injury to the ankle 3 months ago.
Patient Data
Trace ankle joint effusion. Large posterior subtalar joint effusion with synovial thickening. No osteochondral injury of the talar dome or distal tibial plafond.
Syndesmotic ligaments are intact.
Anterior talofibular ligament is intact. Posterior talofibular ligament is intermediate signal and thickened with partial fiber disruption. Calcaneofibular ligament is intact but intermediate signal and thickened.
Deep deltoid ligament is intact but intermediate signal. Tibiospring and superomedial spring ligaments are thickened and intermediate signal. Medioplantar oblique ligament is intact but partially high signal. Inferoplantar longitudinal ligament is not seen, presumed torn.
Dorsal talonavicular and bifurcate ligaments are intact.
Case Discussion
Posterior talofibular ligament injuries are much less common than anterior talofibular and calcaneofibular ligament injuries although they are commonly associated with both. In addition, there is a significant medial collateral / spring ligament complex injury. The MR signal of these injuries reflects the timeframe of 3 months from injury to scanning.