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
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
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
4
Q
What are the associated injuries?
A
- Proximal METATARSAL fractures
- TARSAL FRACTURES
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
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
7
Q
What doe the Lis Franc joint complex consist of?
A
- Tarsometarsal articulation
- Intermetatarsal articulation
- Intertarsal articulation
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
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
- due to osseous architecture
10
Q
What is the classification system of lis franc injury?
A
- Homolateral
- Isolated
- Divergent
- non useful for determining tx and prognosis
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
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
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
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
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
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
