Lis Franc

HistoryLis Franc

Jacques LisFranc De St-Martin (1790 - 1847)

General Surgeon in Napoleonic army

 

Mechanism

 

High energy

 

1.  Twisting / Abduction injury of forefoot

- original description is fall from horse with foot caught in stirrups

- MVA

 

2.  Axial Loading

 

A Extrinsic axial compression applied to heel

B Extreme ankle equinus with axial loading of body weight

 

3.  Direct Crushing

- to dorsum of mid-foot

- greatest risk of compartment syndromes and open fractures

 

Classification

 

A: Quenu & Kuss; Modified by Hardcastle (JBJS 1982)

 

1. Homolateral 

- all 5 metatarsals displaced in same direction

- most common

 

Homolateral Lis FrancLis Franc Homolateral

 

2.  Isolated 

- only 1st MT injured / displaced

 

3.  Divergent 

- 1st MT displaces medially

- other 4 MT displace laterally

- least common

 

B: Myerson

https://www.ncbi.nlm.nih.gov/pubmed/3710321

A: Total incongruity (medial or lateral)

B: Partial incongruity

  B1: Medial

  B2: Lateral (most common)

C: Divergent displacement

  C1: Partial

  C2: Total

 

Anatomy 

 

Bony Stability

 

1-3 MT articulate with cuneiforms

4 & 5 articulate with cuboid

 

Bases of MT wider dorsally than plantar

- form 1/2 of Roman arch 

 

Metatarsal Base Roman ArchFoot CT

 

2nd MT is keystone of transverse MT arch

- medial cuneiform is recessed proximally

- mortise provided for base of second

 

Ligamentous stability

 

Lis Franc ligament

- plantar structure

- 1 cm long x 0.5 cm diameter

- base 2nd MT to medial cuneiform

- avulsion as 'fleck fracture'

 

Note: no intermetatarsal ligament from 1st MT to 2nd

 

Mobility (Sagittal)

 

Medial Column (1st MT) - 3.5 mm

Middle Column (2/ 3) - .6mm

Lateral Column (4/5) - 13mm

 

Examination

 

Swelling and pain

- out of proportion

- must suspect Lis Franc

 

Brusing plantar aspect foot

- indicative of Lis Franc Ligament rupture

 

Signs compartment syndrome

 

X-ray

 

Fleck sign

- avulsion of LF from base of 2nd MT

- can be only sign of isolated Lis Franc Injury

 

Lis Franc Fleck SignLis Franc Fleck Sign

 

Diastasis between 1st & 2nd MT

- may need to perform bilateral weight bearing stress view

 

Lis Franc Diastasis

 

AP / Assess medial column

- medial border 1st MT should line up medial border medial cuneiform

- medial border of 2nd MT should line up with medial border middle cuneiform

 

 Lis Franc Medial Column ViewFoot Medial Column Normal

 

Internal Oblique 30o / Assess lateral column

- medial border 3rd MT line up with medial border lateral cuneiform

- medial border of 4th MT line up with medial border cuboid

 

Lis Franc Lateral ColumnLis Franc Lateral Column Disruption

 

CT scan

 

Confirm displacement of MT from respective joints

 

Lis Franc Displaced TMT Joints CT0001Lis Franc Displaced TMT Joints CT0002

 

Identify fleck sign

 

Lis Franc CT Fleck SignLis Franc CT Fleck Sign and Diastasis

 

Identify dorsal displacement of metatarsals

 

Lis Franc CT Dorsal Displacement MTLis Franc Dorsal Displacement

 

Compression fractures / nutcracker of cuboid

 

Cuboid Fracture Lis Franc

 

MRI

 

Confirm oedema or tear of Lis Franc ligament

Bone brusining tarsometatarsal ligaments

Subluxation of ligaments

 

Intraoperative

Curtis stress views

Hindfoot stabilised & forefoot pronated/ abducted

 

Prognosis

 

Residual pain & stiffness with non-anatomical reduction

- 2° OA

- progressive planovalgus

 

Management

 

Non Operative

 

Sprains with no displacement

- 6/52 in NWB SLPOP

- close serial follow up

- strapping/ medial arch support 6/12

 

Operative

 

Indications

 

Any displacement

 

Closed Technique

 

Indication

- isolated Lis Franc with diastasis

- early diagnosis and treatment

 

Technique

- longitudinal traction

- reduction first intermetatarsal joint

- percutaneous fixation screws

- from medial cuneiform to 2nd metatarsal

 

Lis Franc Isolated Injury FixationLis Franc Medial Column ORIF

 

Open Technique

 

Timing

- wait for swelling to reduce

- may take 2 - 3 weeks

 

Goal

- reduced and stabilise all MTJ that are injured

 

First incision

- dorsal

- between 1st and 2nd MT

- lateral to EHL

- protect branches of SPN

- dorsalis pedis and DPN are in this intermetatarsal space

- very difficult to identify

 

Reduction

- clean out joint

- reduce first and second metatarsal to cuneiforms

- check AP reduction

 

Provisional fixation

- K wire 1st MT to medial cuneiform

- K wire 2nd MT to intermediate cuneiform

- K wire medial cuneiform to base 2nd MT

- +/- K wire medial to intermediate cuneiform if unstable

- insert 4.0 mm cannulated screws

 

Lis Franc Post ORIF

 

2nd incision between 3rd and 4th MT if required

- reduce 3rd and 4th MTPJ

- K wire / screw 3rd MT to lateral cuneiform

- Fix 4th and 5th to cuboid with K wires

- 5th K wire usually inserted percutaneously

- check with oblique view

- may use screw / k wire to 3rd MTPJ

 

Post op

 

Strict NWB for 8/52

- Lis Franc ligament takes time to heal

 

Removal of K wires at six weeks

 

Screw removal

- no sooner than 4/12

- broken screws rarely bothersome

 

Complications

 

Compartment Syndrome

 

Open fracture

- closed reduction and hold with external fixator

 

Midfoot Arthritis

- can develop later

- require midfoot fusion

- some surgeons advocate primary fusion if joint surfaces very damaged / comminuted