LIsfranc…just another one of these obnoxiously named orthopedic injuries? Actually, its named after this guy:
Jacques Lisfranc de St. Martin, who actually was a gynecologist, with a side-gig as one of Napoleons battlefield surgons. Less obnoxious now?
Why does it matter:
- if undiagnosed, it can cause chronic instability, deformity, functional deficiency and pain
- not common (1:55.000), but frequently missed (appr 20% of cases)
- x-ray findings are often subtle or even absent on standard views.
- the Lisfranc joint is a name for all the tarsometatarsal joints,
- the joint separates the forefoot from the midfoot (there is also a hindfoot, if you’re wondering)
- the Lisfranc ligament secures the second metatarsal to the medial cuneiform, serving as a mortise joint anchoring the entire complex and preventing medio-lateral or plantar displacement.
- fractures and concomitant disarticulations of this joint are termed Lisfranc fracture-dislocations
How does it happen:
- often high-energy trauma, such as MVAs, falls from height, and athletic injuries, but can be low-energy rotations, especially in elderly individuals
- most often axial load through hyperplantar flexed forefoot
How do we diagnose it?
- suspect for anyone with severe midfoot pain, tenderness to palpation over midfoot, unable to bear weight. If complete ligamentous tear, ecchymosis on the plantar surface for the foot can sometimes be seen
- stress examination of the midfoot is positive
- the “Piano Key” test: Exacerbation of pain with dorsal and plantar flexion of each digit
- findings may be subtle
- regular XR for foot does not rule out Lisfranc injury, so weight bearing XR or CT is essential if strong suspicion
- XR of foot may show obvious fracture, but other subtle findings may require bilateral weight bearing XRs. Findings include:
- loss of the smooth alignments at the medial border of the second metatarsal with the medial cuneiform and/or the medial border of the fourth metatarsal with the cuboid
- diastasis of the space between the bases of the 1st and 2nd metatarsals (>2mm in a normal foot, or >1mm relative to the contralateral foot)
- CT will give diagnosis if XR is equivocal
Treatment and folllow-up
- if strong suspicion, ortho or podiatry consult if they are in-house
- a significantly displaced injury or dislocation (>2mm widening at the Lisfranc joint) – immediate orthopedics referral in the ED is required for urgent surgical intervention.
- if no ortho in house, give posterior splint and strict non-weight bearing on crutches
- ortho or podiatry f/u within a week
- some of these patients will require operative management