Lisfranc Anatomy: Joint Complex, Ligaments, Injury Classification, and Treatment

The Lisfranc joint complex is the articulation between the midfoot bones (cuneiforms and cuboid) and the forefoot bones (metatarsal bases), named after French surgeon Jacques Lisfranc de St. Martin who described amputations at this level in the Napoleonic era. The Lisfranc joint is the critical structural transition point between the rigid rearfoot/midfoot and the flexible forefoot, and it is stabilized by a complex of interosseous, dorsal, and plantar ligaments — the strongest of which is the Lisfranc ligament proper (interosseous ligament between the medial cuneiform and second metatarsal base). Lisfranc injuries range from subtle ligamentous sprains with no X-ray displacement (frequently misdiagnosed as ankle sprains) to severe fracture-dislocations with complete disruption of the midfoot architecture — and the difference between these extremes is determined by weight-bearing X-rays taken in a standardized position, which are normal in many true Lisfranc injuries on non-weight-bearing films.

Lisfranc Anatomy: Joint Components, Ligaments, and Injury Classification

Component	Anatomy	Function	Injury Significance
Lisfranc ligament (proper)	Strong interosseous ligament running from the lateral surface of the medial cuneiform to the medial base of the second metatarsal; passes between the first and second metatarsal bases; approximately 1cm long	Primary restraint against lateral displacement of the second metatarsal; anchors the keystone of the transverse arch; prevents diastasis between first and second metatarsals	Rupture = Lisfranc injury; even isolated Lisfranc ligament rupture causes midfoot instability; diastasis greater than 2mm between medial cuneiform and second metatarsal base on weight-bearing AP X-ray is diagnostic
Second metatarsal mortise (keystone)	The second metatarsal base is recessed proximally (mortised) between the medial and lateral cuneiforms, creating a locked keystone architecture — like an arch keystone that cannot displace if the surrounding arch is intact	Provides bony constraint to second metatarsal displacement when ligaments intact; the mortise makes isolated second TMT dislocation without ligament rupture very difficult	The recessed position explains why lateral dislocation of the Lisfranc complex always involves the second metatarsal as the primary displaced unit; a fleck avulsion fracture at the base of the second metatarsal or medial cuneiform (the Fleck sign) is pathognomonic of Lisfranc ligament rupture on X-ray
Tarsometatarsal (TMT) joints	Five articulations between the three cuneiforms and cuboid (tarsal bones) and the five metatarsal bases; organized in three columns: medial (1st TMT), middle (2nd and 3rd TMT — most rigid), lateral (4th and 5th TMT on cuboid — most mobile)	Medial column: first TMT mobility allows first ray plantarflexion for windlass mechanism. Middle column: rigid stability for midfoot load transfer. Lateral column: flexibility for terrain adaptation and lateral balance	Injury to middle column (2nd/3rd TMT) produces most instability — the rigid keystone region disrupted; lateral column injuries more likely to be treated conservatively because some mobility is normal and desirable
Plantar ligaments	Plantar tarsometatarsal ligaments are thicker and stronger than dorsal ligaments; the Lisfranc ligament has a plantar component that contributes to stability; plantar fascia attachment to metatarsal bases adds plantar support	Primary resistance to dorsal displacement of metatarsals; plantar ligaments stronger means most displacements are dorsal (metatarsals displace dorsally when plantar ligaments are overwhelmed by dorsiflexion-rotation mechanism)	Plantar ligament injury is more serious than dorsal ligament injury for the same reason — stronger structure disrupted; plantar avulsion fracture at metatarsal base indicates plantar ligament rupture and greater instability
Dorsalis pedis artery	Passes between the first and second metatarsal bases through the intermetatarsal space — directly adjacent to the Lisfranc ligament; can be injured in Lisfranc fracture-dislocations	Primary dorsal blood supply to the foot; its passage through the intermetatarsal space makes it vulnerable to displacement injuries at the Lisfranc joint	Significant Lisfranc dislocations can injure the dorsalis pedis artery — assess dorsal foot pulses after all Lisfranc injuries; expanding hematoma, absent pulses, or compartment syndrome after Lisfranc injury requires emergency vascular evaluation

Lisfranc Injury: Diagnosis Pitfalls and Treatment Algorithm

Injury Pattern	X-ray Findings	MRI / CT Role	Treatment
Subtle ligamentous Lisfranc sprain (low-energy)	Non-weight-bearing X-ray NORMAL or near-normal. Weight-bearing AP: diastasis >2mm between medial cuneiform and 2nd metatarsal base; loss of alignment between medial border of 2nd metatarsal and medial border of middle cuneiform; Fleck sign (avulsion fragment)	MRI: Lisfranc ligament signal abnormality; partial or complete tear; edema at 1st-2nd intermetatarsal space; no avulsion on X-ray but signal change on MRI confirms ligament injury	Truly stable (less than 2mm diastasis, no displacement): non-weight-bearing cast 6 weeks then boot. Unstable (diastasis >2mm): ORIF or arthroscopic Lisfranc ligament fixation with screw bridging cuneiform to 2nd metatarsal base
Lisfranc fracture-dislocation (high-energy)	Obvious displacement on any X-ray view; metatarsals displaced laterally and/or dorsally; multiple fractures at metatarsal bases and tarsals; comminution; compartment syndrome risk	CT: preoperative planning for fracture pattern, articular involvement, degree of comminution; assesses whether ORIF vs primary arthrodesis is preferable	Emergency reduction if neurovascular compromise; definitive ORIF vs primary partial tarsometatarsal arthrodesis; ORIF screws typically removed at 3-4 months; primary arthrodesis of medial/middle column (medial cuneiform to 2nd metatarsal) for comminuted injuries or in older patients with pre-existing arthritis
Missed Lisfranc injury (delayed presentation)	Post-traumatic flatfoot; arthritis at TMT joints on weight-bearing X-ray; often initially diagnosed as ankle sprain; median delay to correct diagnosis 6 months	MRI if chronic: shows ligament scar tissue, early articular cartilage damage; CT for arthritis staging; critical for surgical planning	Salvage surgery: delayed ORIF rarely successful; tarsometatarsal arthrodesis of involved columns is salvage standard; results significantly inferior to acute treatment — reinforces importance of weight-bearing X-rays for any midfoot injury

At Balance Foot & Ankle in Howell and Bloomfield Township, any patient presenting with midfoot pain after trauma — including what appears to be an ankle sprain with dorsal foot tenderness and bruising on the plantar surface of the arch — receives weight-bearing AP X-rays of both feet for comparison, because the diagnosis of subtle Lisfranc injuries is missed on non-weight-bearing films and the consequences of a missed Lisfranc injury are severe and permanent. Call (810) 206-1402.