Lisfranc Injury Flashcards
What is a Lisfranc injury?
Lisfranc injuries are severe injuries to the tarsometatarsal (Lisfranc) joint between the medial cuneiform and the base of the 2nd metatarsal. They can be either solely ligamentous injuries or involving the bony structures of the midfoot (termed a “fracture-dislocation”).
Why are Lisfranc injuries commonly missed?
Lisfranc injuries are unfortunately often missed due to their subtle radiological features, but prompt diagnosis is crucial as neglected injury can lead to ongoing midfoot pain, instability, and deformity.
Briefly describe the anatomy of the Lisfranc joint
The inherent stability of the Lisfranc joint is normally provided by the “keystone” configuration of base of the second metatarsal fitting into a mortise created by the medial and middle cuneiforms. Multiple interosseous ligaments support this area, of which the Lisfranc ligament (from the medial cuneiform to the base of the second metatarsal) is the largest and strongest.
What are the clinical features of Lisfranc injuries?
Lisfranc injuries most commonly occur following severe torsional or translational forces applied through a plantar flexed foot, therefore commonly occur as road traffic accidents or athletic injuries. Following the injury, patients will report severe pain in the midfoot and difficulty in weight-bearing.
On examination, there will be swelling and tenderness over the midfoot; plantar bruising is highly suggestive of a Lisfranc injury. Pain may be provoked by stressing the midfoot.
Patients with tarsometatarsal injuries, resulting from high-energy mechanisms or which result in a significant amount of swelling, should be monitored for features of compartment syndrome.
What investigations should be ordered for Lisfranc injuries?
Any patient involved in a trauma or high-energy injury should be managed and investigated as per ATLS guidelines.
First line imaging for suspected Lisfranc injury is with plain film radiograph, which should include antero-posterior, oblique and lateral foot views whilst weight-bearing. However, obvious widening of tarsometatarsal joint is not always apparent in Lisfranc injuries.
CT scanning is useful in the pre-operative planning of more comminuted fractures. MRI imaging can confirm the presence of purely ligamentous injury.
What are the radiological findings of Lisfranc injuries?
The various subtle radiological signs of a Lisfranc injury include:
- Widening of the interval between the base of the 1st and 2nd metatarsal
- Bony fragment visible (“fleck sign”) in the space between the 1st and 2nd metatarsal, indicates avulsion of the Lisfranc ligament from the base of the second metatarsal
- Disruption of a line drawn from the medial base of the 2nd metatarsal to the medial side of the middle cuneiform (on AP view)
- Malalignment of the medial border of the lateral cuneiform and the medial edge of the 3rd metatarsal, or medial border of the cuboid and the medial edge of the 4th metatarsal (on oblique view)
- Dorsal displacement of the proximal bases of the 1st or 2nd metatarsals (on lateral view)
What is shown in the image?
Lisfranc injury to the left foot (arrow).
Widening of the interval between the base of the 1st and 2nd metatarsal.
Briefly describe the conservative management of Lisfranc injuries
In trauma patients, ensuring the haemodynamic stability of the patient is essential, before any further injuries are managed
For significantly displaced injuries, closed reduction may be required in A&E to correct any gross deformity and help protect the soft-tissue envelope. This involves gentle traction to the midfoot and then a corrective pressure to the metatarsal base, before being placed in a backslab.
Certain Lisfranc injuries without significant displacement can be primarily managed conservatively with cast immobilisation / air-cast boot and non-weight-bearing mobilisation for 6-12 weeks, with regular orthopaedic follow-up and review.
Briefly describe the surgical management of Lisfranc injuries
Patients with clear displacement must be managed operatively. Temporary external fixation can be used if there is significant soft tissue swelling making the injury not amenable to surgery in the first instance.
Definitive fixation most commonly involves screw fixation between the medial cuneiform and second metatarsal, between the medial cuneiform and the first metatarsal, and between the middle cuneiform and second metatarsal. Occasionally, small region specific plate systems can be used.
Primary arthrodesis can be used for severely comminuted or displaced fracture-dislocations.
What are the complications of Lisfranc injuries?
Post-traumatic arthritis is the most common complication following a Lisfranc injury, occurring in up to 25%. It is more common in those with a delayed management by ORIF or those with a non-anatomical reduction; in such cases, they may require midfoot arthrodesis.
Midfoot compartment syndrome is an important complication that can occur following Lisfranc injuries, presenting acutely following the initial injury.
What differentials should be considered for Lisfranc injuries?
Patients presenting with midfoot pain following high-energy injuries should also be assessed for ankle fractures, other tarsal fractures or proximal metatarsal fracture.
