AN

Lisfranc Injuries: Midfoot Trauma — Key Concepts, Imaging, and Management

Overview: Lisfranc injuries and midfoot trauma

  • Lisfranc region anatomy (tarsometatarsal joints): first through third metatarsals articulate with the distal row of cuneiforms; the fourth and fifth metatarsals articulate with the cuboid/other structures of the lateral column.
  • Key stabilizing structures include the Lisfranc ligament (connects medial cuneiform to base of second metatarsal) and adjacent dorsal/plantar ligaments; injuries can be ligamentous and/or involve bony fragments.
  • Clinical relevance: injuries can be subtle on plain radiographs; occult injuries are common; soft-tissue status guides timing and type of definitive surgery.

Case 1: Complete homolateral dislocation (left panel of the lecture)

  • Radiographic finding: all metatarsals displaced laterally relative to the tarso­metatarsal complex; complete homolateral dislocation with total incongruity.
  • Classification cue: described as a Type A injury (total incongruity).
  • Clinical takeaway: this pattern indicates a high-degree disruption of the medial column stability.

Case 2: Lisfranc injury with diastasis and the Fleck sign (Flex sign)

  • Radiographic reading: diastasis between the first cuneiform and adjacent structure (space narrowing between medial column elements).
  • Pathognomonic clue: a small avulsion fragment (piece of bone) at the Lisfranc ligament attachment—classically described as the Fleck sign; the presenter labeled it as “Flex sign.”
  • Additional clue: diastasis in the region and disruption of midfoot alignment with respect to the first ray.
  • Takeaway: presence of diastasis plus an avulsion/fleck fragment strongly supports Lisfranc injury.

Case 3: Dorsal dislocation of the first metatarsal

  • Reading the X-ray: dorsal subluxation/dislocation of the first metatarsal relative to the cuneiforms; uncertain how many metatarsals are involved, but evidence suggests at least the first, possibly second metatarsal involvement (proximal opacities).
  • Mechanism and interpretation: dorsal displacement indicates dorsal ligamentous injury and/or disruption of the medial column stability.

Imaging interpretation notes used in discussion

  • Meary's line (referred to as Mary’s line in the talk): line bisecting the talus and the first metatarsal to assess arch alignment; helps evaluate medial column integrity.
  • Dorsal cortex step-off and joint diastasis on radiographs imply ligamentous rupture and bony displacement, guiding the need for surgical stabilisation.
  • Oblique and lateral views are important to assess the extent of injury, including occult fractures.
  • When there is high clinical suspicion but subtle radiographic findings, cross-sectional imaging (CT) is valuable to assess joint involvement and occult fractures.

Defining and recognizing occult Lisfranc injuries

  • Occult injuries: fractures or instability not clearly visible on plain X-rays but clinically evident.
  • CT scan role: recommended to detect subtle intra-articular involvement or comminution that changes management, especially when plain films are inconclusive.
  • Analogies to other injuries: similar approach to occult calcaneal fractures where CT better delineates injury extent.

Management decisions: when to immobilize vs operate (rugby midfoot injury case)

  • Scenario: 20-year-old rugby player sustained twisting midfoot injury; midfoot region involved; question about optimal definitive treatment.
  • Clinical reasoning: presence of dorsal dislocation, joint disruption, and need to realign the medial arch favors definitive surgical stabilization to restore anatomy and prevent long-term deformity.
  • Discussion point: Options considered included observation, CAM boot with weight bearing, cast immobilization, ORIF, or ORIF with fusion.
  • Final takeaway from discussion: significant dorsal dislocation with step-off and diastasis supports operative stabilization (ORIF) rather than nonoperative management, to anatomically realign and stabilize the medial column; long-term considerations may still dictate fusion in certain contexts.

Post-injury imaging and follow-up considerations

  • Initial management: evaluate soft tissues for compartment syndrome risk; assess skin integrity to guide surgical planning.
  • If severe dislocation with tenting skin or neurovascular compromise: attempt closed reduction in the ED; if not successful, proceed to ORIF with external fixation to allow soft-tissue recovery before definitive fixation.
  • Intraoperative decision-making: whether to perform ORIF or fusion depends on intra-articular involvement, ligamentous integrity, fracture pattern, patient age, and functional goals.

ORIF vs fusion: indications and evidence discussed

  • General principle: literature shows controversy and no one-size-fits-all answer; decisions depend on injury pattern and patient factors.
  • Ligamentous vs bony injury paradigm (as discussed):
    • Purely ligamentous Lisfranc injuries may do better with primary fusion in some studies, especially in older patients or those with highly unstable, non-reconstructable joint surfaces.
    • In injuries with limited bony fragmentation (one or two small fragments), ORIF can restore anatomy and function.
    • In severely comminuted intra-articular injuries, especially in older patients, primary fusion may be favored to avoid ongoing instability and multiple surgeries.
  • Practical rule of thumb from the discussion:
    • If ligamentous injury is relatively intact but there is some crushing or fragmentation, consider ORIF.
    • If injury is severely comminuted or patient is older with lower functional demands, primary fusion may be preferred.
    • The goal is to preserve gait mechanics while addressing instability; fused Lisfranc joints are considered nonessential to motion, so fusion may be tolerated when it improves stability and reduces need for multiple revisional procedures.

Postoperative management and hardware considerations

  • Typical timeline for stabilization after ORIF with transarticular screws and/or K-wires:
    • Non-weight bearing for about 6-8\ weeks (often combined with casting or immobilization) until initial healing is evident.
    • K-wires commonly kept in place for at least 6\ weeks with planned removal around that time; some fixation strategies use pins instead of screws in the fourth and fifth tarsometatarsal joints.
    • Casts, pins, or external immobilization is adjusted based on fragment size, stability, and soft-tissue condition.
  • Fourth and fifth tarsometatarsal joints: typically not fused; if dislocated, reduction and stabilization (often with K-wires) may be performed; in some cases a monorail on the lateral column can help correct length or alignment and reduce impaction.
  • If significant fragmentation: considerations for arthroplasty of the joint or other accessory procedures may be used to address joint congruity.

Practical considerations: soft tissue and timing

  • Soft-tissue condition is crucial; aggressive early surgery can lead to wound complications and dehiscence.
  • If soft-tissue swelling or skin tenting exists, staged management with initial closed reduction/external fixation may be chosen, delaying definitive ORIF or fusion until soft tissues recover.
  • In severe dislocations with neurovascular compromise or open injuries, urgent management aims to restore alignment while protecting soft tissues.

Key takeaways and clinical pearls

  • Lisfranc injuries can present with subtle radiographic signs; always assess for diastasis, fleck sign, and Meary/arch relationships on multiple views.
  • A high index of suspicion and CT imaging are important for occult injuries or when plain films underrepresent injury severity.
  • Management is guided by stability of the medial column, degree of displacement, intra-articular involvement, and patient factors (age, functional demands, soft-tissue status).
  • ORIF is favored when there is clear dislocation with the need to restore anatomic alignment and medial arch; primary fusion may be preferred in certain severely comminuted or ligamentously unstable lesions, especially in older patients.
  • Postoperative plans involve a balance between maintaining stability and protecting soft tissues; non-weight bearing periods typically span about 6-8\ weeks with hardware management (e.g., K-wire removal) around 6\ weeks, while avoiding premature weight bearing.
  • Common non-Lisfranc causes of Lisfranc fracture-dislocations are sports injuries, motor-vehicle collisions, and falls from height; stubbing a toe is not a common cause.
  • Always screen for compartment syndrome and skin integrity; if closed reduction fails in the ED, an external fixator may be used as a temporizing measure before definitive fixation.
  • Literature on the optimal initial surgical approach continues to evolve; decisions should be individualized based on injury pattern, soft-tissue condition, and patient goals.