Lisfranc injury

Introduction

Jacques Lisfranc, Napolean's military surgeon in the early 1800's, described the joints between the tarsal and metatarsal bones as a location amenable to forefoot amputation. The Lisfranc injury was later described as an injury at this level. The mechanism of injury was described as a fall off a horse with the foot caught in the stirrup, producing a forced plantarflexion and twisting. Today, the most common mechanisms include stepping into a hole and twisting the foot, falling from a height, and a head-on motor vehicle collision while pressing on the brake pedal. Injuries to the Lisfranc joints account for approximately one-third of midfoot fracture-dislocations.

Anatomy

The Lisfranc joints are those located between the tarsal and metatarsal bones. The Lisfranc ligament is between the medial cuneiform and the second metatarsal base. The second metatarsal base is proximal compared to the first and third; therefore, the second metatarsal articulates with the cuneiforms in a "keystone pattern". The metatarsals are wider dorsally, resembling the "roman arch" design. This confers stability during weight bearing. Due to this increased stability to plantar directed forces and the fact that the plantar ligaments are stronger, most dislocations are dorsal. Plantar dislocations are rare and occur more often with crushing injuries. The dorsalis pedis has perforating branches, intermetatarsal arteries, that anastamose with the plantar circulation. Disruption of these intermetatarsal arteries can lead to significant hemorrhage and development of compartment syndrome.

Classification

The most commonly used classification of the Lisfranc injury was described by Hardcastle (Hardcastle, JBJS-B, 1982).  It describes the direction of displacement of the tarsal bones as seen on radiographs.  This classification has not been shown to have prognostic value.

-           A - total incongruency of the tarsometatarsal joints with all five metatarsals displaced in the same direction.

-           B - partial incongruency of the tarsometatarsal joints with one or two metatarsals displaced in the same direction.

-           C - divergent displacement with the first metatarsal displaced medially, while any combination of the lateral four metatarsals displaced laterally.

Presentation

Lisfranc injury should be suspected with pain and/or swelling in the midfoot after any trauma or injury to the foot.  This can occur after major motor vehicle collisions or after low energy falls accompanied by twisting of the foot.  Tenderness to palpation and pain with pronation are common complaints.  The patient may or may not be able to weight bear.

Diagnosis

Plantar ecchymosis is commonly found in Lisfranc injuries.  AP / oblique (30deg from AP) / lateral radiographs reveal most injuries, but up to 20% can be missed on initial evaluation.  On the AP radiograph, the medial portion of the second metatarsal should align with the medial border of the middle cuneiform.  On the oblique radiograph, the medial border of the fourth metatarsal should align with the medial border of the cuboid.  Widening of greater than 2 mm between the first and second metatarsal heads or between the medial and middle cuneiforms is abnormal.  Weight bearing AP radiographs are valuable, but may be difficult to perform in the acute setting.  CT scan also shows greater bony detail and is a good option when radiographs do not adequately define the injury.  A fleck sign is a bony avulsion at the base of the second metatarsal.   

Treatment

Operative indications:

For poor reductions, the incidence of arthrosis is 60% compared to 16% (Kuo, JBJS-A, 2000).  Many authors suggest open reduction and internal fixation for any Lisfranc injuries with any amount of displacement.  Open fracture dislocations or injuries accompanied by compartment syndrome require surgery. 

Operative treatment:

In displaced Lisfranc injuries, open reduction is indicated to ensure proper reduction.  A dorsal incision between the first and second metatarsal can be utilized for fixation of the three medial tarsal metatarsal joints, while a dorsal incision between the fourth and fifth metatarsals can expose the fourth and fifth.  Typically reduction begins with the first metatarsal and the medial cuneiform and progresses laterally.  Provisional fixation with K-wires and subsequent screw placement maintains reduction.

Non-operative treatment:

Conservative treatment is typically reserve only for perfectly reduced and stable injuries.  Treatment consists of a non-weight bearing cast for approximately six weeks, followed by six weeks of protected weight bearing in a boot.   

Complications

Early complications

• Vascular compromise                     (~10%)
• Compartment syndrome                (~5%)
• Need for skin coverage                  (~5%)
• Superficial infection                        (~3%)

Late complications

• Loss of reduction
• Screw failure                                              
• Complex regional pain syndrome    (~25%)
• Post-traumatic arthritis                   (~30%)

Outcomes

The outcome is highly dependent on the quality of reduction obtained.   As stated previously, the incidence of arthrosis is 60% in poorly reduced joint compared to 16%.  Fifty percent of patients with nonanatomic reductions were unable to return to work, compared to 25% with anatomic reductions.