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LIs Franc injuries Flashcards

1
Q

What is a Lis Franc injury?

A

A condition characterised by

  • DISRUPTION BETWEEN THE ARTICULATION OF MEDIAL CUNEIFORM AND BASE OF 2ND MT
  • IE disruption of THE TMT JOINT COMPLEX
  • injuries can range form mild sprain to severe dislocations
  • maybe pure ligamentous of fracture-dislocations
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2
Q

What is the epidemiology of Lis Franc injuries?

A
  • Incidence 0.2% of all fractures
  • more common 3rd decade
  • more common in men
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3
Q

Can you describe the mechanism of injury?

A
  • RTA
  • Falls from height
  • atheletic injuries

Mechanism is usually

  • AXIAL LOAD THRU A HYPERPLANTAR FLEXED FOREFOOT
  • METATARSAL displaces in DORSAL/LAT DIRECTION
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4
Q

What are the associated injuries?

A
  • Proximal METATARSAL fractures
  • TARSAL FRACTURES
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5
Q

What is the prognosis of these injuries ?

A
  • Frequently missed -> chronic pain, deformity, dysfunction
  • Tarsometarsal fracture-dislocations are easily missed and diagnosis is critical
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6
Q

Where does the LIs franc ligament run?

What is it critical for ?

A
  • Medial cuneiform to base of 2nd MT head on PLANTAR SURFACE

​Use

  • Critical to Stabilizing the 2nd MT
  • Maintaince of midfoot arch
  • Tightens with pronation and abduction of forefoot
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7
Q

What doe the Lis Franc joint complex consist of?

A
  • Tarsometarsal articulation
  • Intermetatarsal articulation
  • Intertarsal articulation
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8
Q

What are the other tarsometatarsal ligaments called and their role ?

A
  • Plantar tarsometatarsal ligament
    • injury of plantar ligament between the medial cuneiform and 2nd/3rd metatarsal along with Lis Franc ligament-> transverse instability
  • Dorsal tarsometatarsal ligament
    • dorsal ligaments are weak and therefore bony displacement with injury is often dorsal
  • Intermetatarsal ligaments
    • Between 2-5th MT
    • no direct ligamentous attachment between 1st and 2nd MT
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9
Q

What are the biomechanics of the lis franc joint complex?

A
  • Inherently stable
    • due to osseous architecture
      • 2nd MT fits in mortise created by cuneiform and recessed middle cuneiform- ‘keystome configuration’
      • ligamentous restraints
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10
Q

What is the classification system of lis franc injury?

A
  • Homolateral
  • Isolated
  • Divergent
  • non useful for determining tx and prognosis
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11
Q

What are the signs and symptoms of lis franc injury?

A

Symptoms

  • Severe pain
  • inability to weight bear

Signs

  • Medial plantar brusing
  • swelling throughout midfoot
  • tenderrness over TMT joint
  • instability test
    • Gasp MT heads adn apply dorsal force to forefoot while other hand palpates the TMT joints
    • Dorsal subluxation suggests instability
    • IF first /second MT can be displaced medially and laterally, global instability is present and surgery required
  • Provaction test
    • may reproduce pain with pronation and abduction of forefoot
  • Check for compartment syndrome
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12
Q

What investigations are useful for DX of lis franc injury?

A
  • Ap , lateral and oblique x rays- weight bearing
  • stress radiograph
    • disruption of continuity of a line drawn from medial base of 2nd MT to medial side of middle cuneiform
    • widening of interval between 1st and 2nd rays
    • Medial side of base of 4th MT doesn’t line up with medial side of cuboid on oblique view
    • Metatarsal base dorsal subluxation on lateral view
    • Disruption of medial column line - tangential to medial aspect of navicular adn medial cuneiform

CT

  • Preop planning

MRI

  • can be used to confirm purely ligamentous injury
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13
Q

What is wrong with this xray?

A
  • disruption of continuity of a line drawn from medial base of 2nd MT to medial side of middle cuneiform
  • Medial side of base of 4th MT doesn’t line up with medial side of cuboid
  • Disruption of medial column line - tangential to medial aspect of navicular and medial cuneiform
  • suggestive of LIs franc injury
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14
Q

What is wrong with this xray?

A
  • Bony ‘Fleck sign’ in 1st MT space
  • represents avulsion of lis franc ligament from base of 2nd MT
  • diagnostic of Lis franc injury
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15
Q

What is the tx of lis franc injury?

A

Non operative

  • if no displacement on WB & stress radiographs
  • No evidence of Bony injury on CT
  • poor candiates for surgery- DM neuropathy, nonambulatory
  • Cast IMMOBILISATION for 8 weeks

​Operative

  • ORIF
    • any evidence of instability >2mm shift
    • anatomical reduction requierd for good result
  • ​Primary arthrodesis of 1st, 2nd and 3rd TMT joints
  • purely ligamentous injury
  • Level 1 evidence equal functional outcomes nad decreased rate of hardwear removal or revision surgery cf Orif
  • **Alternative to orif in pt with instability

Medial column tarsometarsal function shown to be superior to combine medial and lateral column tarsometatarsal arthrodesis**

  • Midfoot arthrodesis
  • destabilisation of midfoot and arch collapse & forefoot adduction
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16
Q

Describe the technique of operative fixation?

A

approach

  • single or dual longitudinal incisions can be used based on injury pattern and surgeon preference
  • longitudinal incision made in the web space between first and second rays between EHL and EHB
  • first TMT joint is exposed between the long and short hallux-extensor tendons

​Reduction

  • Reduce intercuneiform instability first
  • reduce and fix 1st TMT ( 1st mt to medial cuneiform)
    • distal to proximal screw using a poxket hole( engage distal cortec without breaking it)
  • reduce 2nd TMT
    • fix with screw from medial cuneiform thru to base of 2nd MT- full threaded 4.0mm screw
  • Reduction and fixation of 3rd TMT
    • dorsal base of 3rd MT to cuneiform row
  • reduction of 4/5th MT
    • often occurs when medial columns are restored
    • k wires used into cuboid
    • allow mobility once removed
17
Q

What post op tx would you advise post orif of lis franc ?

A
  • Early midfoot rom
  • Protected weight bearing and hard wear removal k wires 6-8 wks, screws 3-6months
  • FWB at 8-10 weeks
  • no vigorius activity 9-12 months
18
Q

Decribe the technique for arthodesis TMT for purely ligamentous lis franc injury?

A
  • dual incision
    • 1st webspace between EHL and EHB
    • fusion of 1st TMT, 2nd TMT and 3rd TMT
19
Q

What are the complications of lis franc injury?

A
  • Post traumatic arthritis
    • Most common complication
    • may gain altered gait and longterm disability
    • tx midfoot arthritis with midfoot arthrodesis
  • Non union
    • uncommon
    • revision surgery indicated unless elderly

Pod practice (75 decks)

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