Lisfranc and Midfoot Injuries

KEY FACTS

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The midfoot includes 5 tarsal bones: Navicular, cuboid, and 3 cuneiforms (medial, 1st; middle, 2nd; and lateral, 3rd).
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Mobile or “essential” midfoot joints include:
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  Talonavicular
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  Calcaneocuboid
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  Cuboid: 4th and 5th metatarsals
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Nonmobile or “nonessential” midfoot joints include:
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  Naviculocuneiform
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  Metatarsocuneiform
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Navicular fracture outcome is dependent on fracture pattern and restoration of normal anatomy.
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  Restoration of normal anatomical alignment leads to better outcomes in displaced fractures.
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  Increasing comminution tends to result in more frequent poor outcomes.
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Nondisplaced cuneiform fractures, especially without associated midfoot injuries, may be treated conservatively with a well-padded short leg splint.
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Displaced cuneiform fractures require ORIF.
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Injury to the tarsometatarsal joints include a wide spectrum of soft tissue and bony injuries.
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  They may be purely ligamentous or purely fracture or a combination of both (fracture-dislocations).
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  They may be low energy, high energy, or somewhere in between.
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Radiographic evaluation of Lisfranc injuries requires:
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  Weight-bearing anteroposterior, lateral, and 30° oblique views
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  Stress radiographs
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Lisfranc injuries can be surgically treated with ORIF or primary fusion.
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There have been 2 randomized studies comparing primary fusion to ORIF.
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  One suggested improved outcomes with primary fusion.
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    Especially with regard to decreased need for hardware removal surgery
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  The other did not show any major difference in outcome.

Anatomy and Function of Midfoot

General

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The midfoot includes 5 tarsal bones: Navicular, cuboid, and 3 cuneiforms (medial, 1st; middle, 2nd; and lateral, 3rd).
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  The bases of the metatarsals are also part of the midfoot structure.
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It forms the transverse arch of the foot and part of the longitudinal arch.
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The navicular articulates in a mobile relationship with the talus proximally.
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  Motion at the talonavicular joint is essential for normal foot function.
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The navicular articulate distally with the 3 cuneiforms.
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  Stability at this articulation is more important than flexibility.
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The cuboid articulates with the anterior process of the calcaneus proximally and with the 4th and 5th metatarsal bases distally.
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  Both proximal and distal articulations are mobile.
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The cuneiforms articulate with navicular proximally, 1st-3rd metatarsal bases distally, and cuboid laterally (with lateral or 3rd cuneiform).
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  These articulations are rigid.
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The 2nd metatarsal meets the middle cuneiform in a rigid joint.
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  This articulation is more proximal than the 1st and 3rd joints.
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  This is referred to as the “keystone” of the midfoot.
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The transverse tarsal, or Chopart, joint is formed by the talonavicular and calcaneocuboid joints.
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  This complex is stiff with hindfoot varus during the toe-off phase of gait.
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    It provides a rigid lever for ambulation.
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  Hindfoot valgus “unlocks” the transverse tarsal joint.
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Mobility at the transverse tarsal joint is necessary for normal gait.
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  Fusions are not well tolerated.
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  Temporary spanning fixation of the talonavicular and calcaneocuboid joints in the setting of trauma will not be durable.
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    It is often removed once healing of the traumatized foot has occurred.
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Fixation from 4th or 5th metatarsals into cuboid also restricts normal foot motion and is not well tolerated.
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  If performed, fixation is often removed once healing has occurred in the traumatized foot.
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The remaining midfoot joints (naviculocuneiform and medial 3 metatarsocuneiform) are relatively stable and nonmobile articulations.
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  They tolerate permanent fixation well.

Midfoot Injuries

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Although it is possible to fracture a single bone of the midfoot complex, many injuries are more complex.
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The tight ligamentous connections across the midfoot bones means that displacement of any 1 midfoot bone often must include injury to ligaments or adjacent bones.
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  These injuries will affect the stability and structure of the midfoot.
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The navicular and 3 cuneiforms are packed tightly together and essentially function as a block unit.
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The 2nd and 3rd metatarsals are tightly connected to each other and to the cuneiforms.
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There is a proximal transverse intermetatarsal ligament that connects the bases of the 2nd-5th metatarsals.
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  Medially, it runs to the medial cuneiform, not the 1st metatarsal.
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There is also a distal transverse intermetatarsal ligament that connects the distal end of the 2nd-5th metatarsals.
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  Medially, it inserts on the lateral sesamoids.
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  Again, the 1st metatarsal is not connected.
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The Lisfranc ligament runs from the medial cuneiform to the base of the 2nd metatarsal.
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  It is mostly a plantar structure.
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The 1st metatarsal has ligamentous connections to the medial cuneiform.
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  There is no ligamentous connection to the other midfoot joints.
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The various midfoot injury patterns seen are a reflection of these connections.

Cuneiform Fractures

Introduction

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Isolated cuneiform fractures are rare.
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They often occur in conjunction with other midfoot injuries.
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  Lisfranc injuries
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  Cuboid fractures
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  Navicular fractures
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They most commonly involve the medial (1st) cuneiform.
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Injuries may occur via a direct mechanism (direct blow) or an indirect mechanism (violent forefoot abduction or adduction).

Evaluation

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Patients may complain of generalized midfoot pain or may isolate their area of maximal pain to the medial midfoot.
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  Patients often are unable to bear weight on the injured foot.
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Physical examination may reveal signs of typical midfoot injury, including the following.
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  Edema
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  Ecchymosis
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  Tenderness
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Skin examination is necessary to rule out impending compromise by bony deformity.
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  This is most likely in the setting of multiple bony or ligamentous injuries.
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    Such as Lisfranc injury
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Be suspicious of compartment syndrome with severe swelling and high-energy mechanisms.

Treatment

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Nondisplaced cuneiform fractures, especially without associated midfoot injuries, may be treated conservatively with a well-padded short leg splint.
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  Protected weight bearing is maintained acutely.
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Displaced cuneiform fractures require open reduction and internal fixation (ORIF).
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  Interfragmentary compression, if possible, may be employed for noncomminuted fractures.
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Incision is often centered dorsally over the interspace between the 1st and 2nd metatarsal bases and the medial (1st) and middle (2nd) cuneiforms.
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Comminuted fractures may be stabilized to adjacent, uninjured cuneiforms with intercuneiform screw fixation.
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Associated midfoot injuries, such as Lisfranc injuries, should also be treated accordingly.
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Temporary bridge plating may be employed for severely comminuted medial cuneiform fractures.
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  It maintains medial column length.
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  It can bridge from the base of the 1st metatarsal to the navicular or talus.