Lisfranc Fracture-Dislocation

Diagnosis Definition

• The Lisfranc joint complex includes the tarsometatarsal (TMT), intermetatarsal (IMT), and intertarsal joints
• The Lisfranc ligament attaches the medial cuneiform to the base of the 2nd MT and has 1) dorsal, 2) interosseous, and 3) plantar components; variable ligaments attach 2nd-5th MT bases and the cuneiforms to their neighbors
• Lisfranc injuries range from sprain to fracture with or without dislocation and result from crushing or rotational force on a plantar flexed forefoot
• Fractures are classified as 1) homolateral (MTs displaced in same direction),  2) isolated (1-2 MTs displaced) or 3) divergent (MTs displaced in opposite directions)

Imaging Findings

• MRI sequences include sagittal T1 and STIR, axial PD and T2 Fat-sat (FS), and coronal PD and T2 FS
• The normal Lisfranc ligament is homogeneous or striated and has low or intermediate signal
• On MRI, Lisfranc injuries may be seen as high signal bone bruises, fractures, dislocations, increased signal within the ligaments, periligamentous edema, or ligament disruption

KEY IMAGES

Pearls

• Undiagnosed Lisfranc sprains can lead to chronic instability and early osteoarthritis
• Low signal scars of chronic ligament rupture may simulate an intact ligament on T2
• Tarsometatarsal edema and multiple microfractures are highly suggestive of Lisfranc injury

References

1. Cheung Y, Rosenberg ZS. MR imaging of ligamentous abnormalities of the ankle and foot. MRI Clinics of North America 2001; 9:507-31