Case 73 - Lisfranc fracture/dislocation

Summary

Imaging description

The Lisfranc joint is strictly defined as the articulation between the midfoot tarsals (cuneiforms and cuboid) and the second through fifth metatarsals. A Lisfranc injury is diagnosed usually on radiographs. In particular, an unstable Lisfranc injury can be diagnosed as being present if there is misalignment at the second tarsometatarsal articulation (Figure 73.1). Specifically, the medial edge of the base of the second metatarsal should perfectly line up with the medial edge of the middle cuneiform in a normal foot. If a Lisfranc injury is clinically suspected and a non-weightbearing foot radiograph is normal, then a weightbearing AP foot radiograph must be obtained to look for any second tarsometatarsal articulation misalignment. If a weightbearing radiograph cannot be obtained or if there is still considerable clinical concern for a Lisfranc injury of the foot, then an MRI of the foot should be performed. On the coronal images of the foot, one should specifically look for a high grade sprain of the plantar Lisfranc ligament between the medial cuneiform and the bases of the second and third metatarsals (the pC1-M2M3 Lisfranc ligament). A high grade sprain of this ligament has an approximately 95% positive predictive value for an unstable Lisfranc injury; therefore, indicating surgical treatment should be considered (Figure 73.2).

Importance

Inadequate early treatment of Lisfranc joint injuries can result in substantial instability, deformity, and dysfunction of the foot. This can be especially debilitating in athletes and people that have an occupation that requires standing and/or walking.