Mechanism
Low energy
- sport
- football
- gymnastics
Definition
Injury to the Lis Franc Ligament with instability / diastasis
Other ligamentous injuries
- medial cuneiform (C1)—intermediate cuneiform (C2) instabiility
- medial cuneiform (C1)—first metatarsal bone (M1) instability
- intermediate cuneiform (C2)—second metatarsal bone instability
Anatomy
Bony Stability
| Alignment | Alignment | Roman arch | Keystone / Mortise |
|---|---|---|---|
|
1st - medial cuneiform 2nd - middle cuneiform 3rd - lateral cuneiform |
4th and 5th metatarsals articular with cuboid |
Bases of metatarsal wider dorsally than plantar Form half of Roman arch |
2nd metatarsal is keystone of transverse metatarsal arch - medial cuneiform is recessed proximally - mortise provided for base of second |
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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'
X-ray
1. Diastasis of the intermetatarsal gap between the 1st and 2nd metatarsals
2. Enlargement of the space between the medial cuneiform and 2nd metatarsal base
3. Second metatarsal Fleck sign - avulsion of Lis Franc ligament from base of 2nd metatarsal
4. Dorsal subluxation of the metatarsal
Weight bearing xrays
CT
Fleck sign
MRI
Tear of Lis Franc ligament
Management
Options
Screw fixation
Flexible fixation - suture button / internal brace
Plate fixation
Arthrodesis
- 60 isolated Lis Franc Ligament injuries
- half treated with screw, half with suture button
- no difference in functional outcome at 1 year
- recurrent diastasis with 1/30 screws and 2/30 suture buttons
- systematic review and meta-analysis
- flexible fixation versus ORIF versus primary arthrodesis
- 25 studies and 300 patients
- better outcomes and return to activity with flexible fixation
One Incision Approach
Dorsal incision
- between 1st and 2nd metatarsal
- protect branches of SPN
- retract EHL medially
- dorsalis pedis and DPN are in this intermetatarsal space
Reduction
- medial incision over medial cuneiform
- clamp medial cuneiform to base 2nd metatarsal
Screw fixation
AP view
- 1st metatarsal to medial cuneiform - screw
- 2nd metatarsal to intermediate cuneiform - screw
- medial cuneiform to base of second metatarsal - screw
+/- medial cuneiform to intermediate cuneiform - screw
Suture button fixation
Removal of Lis Franc screws
Chronic Ligamentous Lis Franc Instability
Options
Ligamentous reconstruction
Arthrodesis