Overview
Lisfranc injuries involve disruption of the tarsometatarsal (TMT) joint complex of the midfoot. These injuries range from subtle ligament sprains to severe fracture-dislocations. Accurate diagnosis is critical because missed Lisfranc injuries can lead to chronic pain, midfoot instability, and post-traumatic arthritis.
The Lisfranc joint complex plays an essential role in maintaining the structural integrity of the medial longitudinal arch of the foot. Disruption of this joint complex leads to significant functional impairment and difficulty with weight bearing.
Lisfranc injuries are often misdiagnosed, particularly when the injury is purely ligamentous and radiographic findings are subtle. Early recognition and appropriate treatment are therefore essential to restore midfoot stability and prevent long-term disability.
Anatomy of the Lisfranc Joint
The Lisfranc joint complex consists of the articulation between the metatarsal bases and the tarsal bones of the midfoot.
- First metatarsal articulates with medial cuneiform
- Second metatarsal articulates with intermediate cuneiform
- Third metatarsal articulates with lateral cuneiform
- Fourth and fifth metatarsals articulate with cuboid
The second metatarsal base fits into a recess between the medial and lateral cuneiforms, forming a keystone that stabilizes the midfoot.
Lisfranc Ligament
The Lisfranc ligament is a strong interosseous ligament connecting the medial cuneiform to the base of the second metatarsal. It is the primary stabilizer of the tarsometatarsal joint complex.
- Connects medial cuneiform to second metatarsal
- Prevents separation of first and second metatarsals
- Key stabilizing structure of the midfoot
There is no ligament between the first and second metatarsals, which explains why disruption of the Lisfranc ligament leads to diastasis between these bones.
Mechanism of Injury
Lisfranc injuries may occur due to both high-energy and low-energy mechanisms.
- Motor vehicle accidents
- Falls from height
- Sports injuries
- Twisting injury of foot
- Axial load applied to plantar-flexed foot
A classic mechanism involves axial loading of a plantar-flexed foot, which disrupts the Lisfranc ligament and leads to displacement of the metatarsals.
Classification
Several classification systems have been proposed for Lisfranc injuries. The Hardcastle classification is commonly used and describes displacement patterns.
| Type | Description |
|---|---|
| Type A | Total incongruity of TMT joints |
| Type B | Partial incongruity |
| Type C | Divergent displacement |
Clinical Features
- Midfoot pain and swelling
- Difficulty bearing weight
- Tenderness over tarsometatarsal joints
- Bruising on plantar surface of foot
- Instability of midfoot
Plantar ecchymosis is considered a classic clinical sign of Lisfranc injury.
Radiographic Evaluation
- AP foot radiograph
- Oblique foot radiograph
- Lateral foot radiograph
- Weight-bearing radiographs
- CT scan for detailed fracture assessment
A key radiographic sign is widening between the first and second metatarsal bases, indicating disruption of the Lisfranc ligament.
Important Radiographic Signs
| Radiographic Finding | Significance |
|---|---|
| Diastasis between 1st and 2nd metatarsals | Lisfranc ligament injury |
| Fleck sign | Avulsion fragment at ligament attachment |
| Malalignment of metatarsal bases | TMT joint instability |
Management
Management depends on the stability of the injury and the degree of displacement.
| Treatment | Indication |
|---|---|
| Immobilization | Stable injuries |
| ORIF with screws | Displaced injuries |
| Primary arthrodesis | Severe ligamentous injuries |
Complications
- Post-traumatic arthritis
- Chronic midfoot instability
- Persistent pain
- Malunion
- Loss of arch height
Exam Pearls
- Lisfranc ligament connects medial cuneiform to second metatarsal
- Plantar ecchymosis is classic clinical sign
- Fleck sign indicates Lisfranc ligament avulsion
- Missed injuries lead to midfoot arthritis