Summary

The Lisfranc injury refers to a disruption of the tarsometatarsal (TMT) joint complex, specifically involving the Lisfranc Ligament which anchors the 2nd Metatarsal base to the Medial Cuneiform. This ligament is the Keystone stabilizer of the midfoot "Roman Arch". Since there is NO transverse intermetatarsal ligament between the 1st and 2nd metatarsals, the Lisfranc ligament is the sole restraint preventing the medial column (1st Ray) and middle column (2nd Ray) from splitting apart (Diastasis). Injuries range from subtle "Midfoot Sprains" (often missed) to gross fracture-dislocations. Missed injuries (up to 20%) lead to rapid arch collapse and debilitating midfoot arthritis. Management determines the future of the foot: Primary Arthrodesis (Fusion) is increasingly the gold standard for purely ligamentous injuries, while ORIF (Bridge Plating) is favored for bony fractures. [1,2,3]

Key Facts

• The "Keystone": The base of the 2nd Metatarsal is recessed between the Medial and Lateral Cuneiforms, locking the midfoot arch like a keystone in a Roman arch.
• Fleck Sign: A tiny avulsion fracture found in the space between the bases of the 1st and 2nd metatarsals. It represents the avulsion of the Lisfranc ligament and is pathognomonic for instability.
• Mechanism: Vertical axial load on a plantarflexed foot (e.g., horse stirrup injury, missing a step, tackle from behind, windsurfing strap).
• The Trap: 20% of injuries are missed on initial X-ray because non-weight bearing views show spontaneous reduction. Weight Bearing X-rays are mandatory to unmask instability.

Clinical Pearls

"Look at the Sole": Plantar Ecchymosis (bruising on the sole of the foot) is undoubtedly the most specific clinical sign. A "sprained foot" with a bruised sole is a Lisfranc injury until proven otherwise.

"The Piano Key Test": Grasping the metatarsal heads and articulating them individually (Dorsiflexion/Plantarflexion stress) causes severe pain in the midfoot if the TMT joint is unstable.

"Listen for the Pop": Patients often report a sensation of "stepping in a hole" followed by a pop.

                   LISFRANC INJURY
                         ↓
              IS IT STABLE? (WB X-ray)
             ┌───────────┴───────────┐
            YES                     NO
       (Grade I Sprain)     (Diastasis >2mm)
            ↓                       ↓
     NON-OPERATIVE               SURGICAL
     (Cast NWB 6w)            (Fixation/Fusion)
                                    ↓
                          BONY?          LIGAMENTOUS?
                         ┌──┴──┐         ┌─────┴─────┐
                       ORIF    ORIF    PRIMARY      ORIF
                      (Plate) (Screw)  FUSION     (Bridge)

Indications

• Stable on Weight Bearing X-ray (No diastasis).
• Grade I Sprain (MRI confirmed).
• "Extra-articular" fractures with no instability.

Protocol

• 0-6 Weeks: Non-Weight Bearing Cast. (Absolutely no cheating). Ligaments take longer to heal than bone.
• 6-10 Weeks: Walking Boot (Partial weight).
• 10 Weeks+: Stiff soled shoe / Carbon fiber insert.
• Follow-up: X-rays every 2 weeks to ensure no late displacement.

1. ORIF (Open Reduction Internal Fixation)

• Indication: Bony fracture-dislocations. Bone heals predictably.
• Technique:
  • Dorsal Bridge Plating: Spans the joint surface without damaging the cartilage. The current preference for comminuted fractures. Plates are removed at 6 months.
  • Trans-articular Screws: Placed through the joint (Medial Cuneiform -> 2nd Met Base). Extremely rigid. cons: Damages articular cartilage. Screws break if weight bearing starts too early. Must be removed at 4 months.
• Approach: Two dorsal incisions.
  1. Between 1st/2nd Ray (Protects NV bundle).
  2. Between 3rd/4th Ray. (Lateral).

2. Primary Arthrodesis (Fusion)

• Indication: Purely Ligamentous injuries or severe comminution of joint surface.
• Rationale: Ligaments heal with scar tissue (laxity), leading to recurrence and arthritis. The TMT joints (1-3) have very little functional motion anyway. Fusing them immediately gives a stable, pain-free foot.
• Technique: Preparation of joint surfaces (remove cartilage), bone graft, and rigid compression screws/plates.
• Evidence: Ly & Coetzee (2006) RCT showed Primary Fusion had significantly better outcomes (AOFAS scores) and fewer re-operations than ORIF for ligamentous injuries.

Primary Fusion vs ORIF

• Henning et al (2009): Confirmed that primary fusion provides strictly better functional results for ligamentous injuries.
• Consensus:
  • Bony Injury -> ORIF.
  • Ligamentous Injury -> Fusion.
  • Elite Athletes -> ORIF allows faster return (sometimes), but higher risk of late arthritis.

Hardware Removal

• Screws: Must be removed at 12-16 weeks before full loading.
• Plates: Can be left in longer, but usually irritate dorsal skin (shoewear) and are removed at 6-12 months.

The Injury

You have broken the "Keystone" of your foot's arch. The main ligament (Lisfranc) that holds your foot bones together has snapped. It is like the mortar falling out of a brick archway.

Why do I need surgery?

If we don't fix it, the bones will drift apart when you stand on them. Your arch will collapse, and the rubbing bones will cause severe arthritis within a few years, making walking very painful.

Fix vs Fuse?

• Fix: We use plates to hold the bones while they heal. We assume the bone will knit together.
• Fuse: For ligament tears, the ligament never heals "tight" again. We glue the bones together permanently. This sounds drastic, but these joints don't move much anyway, and a stiff, painless foot is better than a loose, painful one.

Recovery

• No Weight: You cannot walk on this foot for 6-8 weeks. Not even a hop.
• Boot: Then a boot for another month.
• Swelling: Will last for 6-12 months.
• Return to Sport: 6-9 months minimum.

Q1: What is the Fleck Sign? A: A small avulsion fracture found in the space between the base of the 1st and 2nd metatarsals. It is pathognomonic for a Lisfranc ligament avulsion.

Q2: Describe the "Keystone" anatomy. A: The base of the 2nd Metatarsal is recessed proximally, locked between the Medial and Lateral Cuneiforms. This mortise configuration provides intrinsic bony stability to the midfoot arch.

Q3: Where does the Lisfranc Ligament run? A: From the Lateral aspect of the Medial Cuneiform to the Medial aspect of the 2nd Metatarsal Base. It is an interosseous ligament.

Q4: Why is Primary Fusion preferred for ligamentous injuries? A: Because ligaments heal with scar tissue (creep), leading to residual instability. ORIF requires hardware removal and has a high rate of late arthritis requiring secondary fusion. Primary fusion solves the problem in one operation with better functional scores.

(End of Topic)