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Remote Fellowship – Foot & Ankle Fundamentals – 11/2/2020

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Diagnosis

Lisfranc Ligament Rupture

Case Discussion

The Lisfranc joint is the articulation between the medial cuneiform (C1) and the second metatarsal (M2). The Lisfranc ligament is considered the main stabilizer of the Lisfranc joint. It consists of a dorsal (C1-M2), interosseous (C1-M2), and plantar component (C1-M2 and C1-M3 components), making the Lisfranc ligament complex. The interosseous component is the strongest and thickest of the three ligaments. The most common mechanism of injury is axial loading of a plantarflexed foot.

Several classifications exist to describe Lisfranc injuries. The most commonly used is the Nunley and Vertullo classification. This divides injuries into 3 different stages based on clinical findings, weight-bearing radiographs, and bone scintigraphy.

– Stage I: LISFRANC ligament sprain without diastasis

– Stage II: Lisfranc ligament rupture with 2-5 mm of diastasis without loss of longitudinal arch height

– Stage III: Lisfranc ligament rupture with 2-5 mm of diastasis and loss of longitudinal arch height.  Another method of describing and categorizing lisfranc injuries relates to the character of the displacement.  such displacement includes: convergent, where all the metatarsals displace in the same direction; and divergent, where the first metatarsal base displaces medially and the remaining metatarsal bases displace laterally.  convergent displacement is also described as homolateral, where all of the metatarsals 1 thru 5 displace laterally.  Another homolateral variant is when the 2nd thru 5th metatarsals displace laterally, but the 1st metatarsophalangeal joint remains congruent.  Finally, in the isolated type, only 1 or 2 metatarsals dislocate or displace dorsally.  The roman column recessed position of the 2nd metatarsal base makes it particularly prone to transverse fracture with lisfranc insults.

Early recognition of subtle Lisfranc injuries is important as missing these injuries may lead to degenerative arthritis, loss of arch height, chronic instability, and pain at the midfoot-forefoot articulation. It has been estimated that as many as 20% of Lisfranc joint injuries are missed on initial radiographs, especially when they are purely ligamentous in nature, hence the importance of MRI and weight-bearing radiographs.

On MRI the uninjured lisfranc ligament is a continuous band-like structure with homogeneous low signal on all pulse sequences. Irregular contour and/or partial or complete discontinuity indicates injury. When acutely injured, it appears as increased signal on T1 weighted images, and hyperintense with surrounding edema on T2 weight images. In partial tears and/or sprains, elongation and thinning of the ligament may be appreciated along with periligamentous edema on T2 weighted images.

Osteoedema around the Lisfranc joint is an important ancillary feature or secondary sign of potential underlying Lisfranc ligament injury and should prompt close examination of the Lisfranc ligament.

Key Images

Lisfranc ligament rupture in a 21-year-old man with a left foot injury from playing football 3 days prior.

A. Axial PD image of the left foot shows diffuse edema between the bases of the 1st and 2nd metatarsal bones and between the 1st cuneiform and base of the 2nd metatarsal bone. The dorsal, interosseous, and plantar lisfranc ligaments are not intact (red arrow). Approximately 2 mm lateral translation of the 2nd metatarsal base on the middle cuneiform is noted (green arrow).
B. Axial T2 image shows diffuse edema between the bases of the 1st and 2nd metatarsal bones and between the 1st cuneiform and base of the 2nd metatarsal bone. The dorsal, interosseous, and plantar lisfranc ligaments are not intact (red arrow). Approximately 2 mm lateral translation of the 2nd metatarsal base on the middle cuneiform is noted (green arrow).
C. Coronal T1 image of the left foot shows disruption of the lisfranc ligament complex, surrounding hemorrhagic edema (red arrow), and diastasis between the 2nd metatarsal base and medial cuneiform.
D. Coronal T2 image of the left foot shows disruption of the lisfranc ligament complex, surrounding hemorrhagic edema (red arrow), and diastasis between the 2nd metatarsal base and medial cuneiform.

References

  1. Amuti A, Ding HY, Liu LG. Magnetic resonance imaging of the Lisfranc ligament. J Orthop Surg Res 2018; 13:282
  2. Nunley JA, Vertullo CJ. Classification, investigation, and management of midfoot sprains: Lisfranc injuries in the athlete. Am J Sports Med 2002; 30(6) 871-878