Lisfranc and Midfoot Injuries





KEY FACTS





  • The midfoot includes 5 tarsal bones: Navicular, cuboid, and 3 cuneiforms (medial, 1st; middle, 2nd; and lateral, 3rd).



  • Mobile or “essential” midfoot joints include:




    • Talonavicular



    • Calcaneocuboid



    • Cuboid: 4th and 5th metatarsals




  • Nonmobile or “nonessential” midfoot joints include:




    • Naviculocuneiform



    • Metatarsocuneiform




  • Navicular fracture outcome is dependent on fracture pattern and restoration of normal anatomy.




    • Restoration of normal anatomical alignment leads to better outcomes in displaced fractures.



    • Increasing comminution tends to result in more frequent poor outcomes.




  • Nondisplaced cuneiform fractures, especially without associated midfoot injuries, may be treated conservatively with a well-padded short leg splint.



  • Displaced cuneiform fractures require ORIF.



  • Injury to the tarsometatarsal joints include a wide spectrum of soft tissue and bony injuries.




    • They may be purely ligamentous or purely fracture or a combination of both (fracture-dislocations).



    • They may be low energy, high energy, or somewhere in between.




  • Radiographic evaluation of Lisfranc injuries requires:




    • Weight-bearing anteroposterior, lateral, and 30° oblique views



    • Stress radiographs




  • Lisfranc injuries can be surgically treated with ORIF or primary fusion.



  • There have been 2 randomized studies comparing primary fusion to ORIF.




    • One suggested improved outcomes with primary fusion.




      • Especially with regard to decreased need for hardware removal surgery




    • The other did not show any major difference in outcome.








This patient sustained a type 3 navicular fracture in a motor vehicle crash. Anteroposterior and oblique injury radiographs are shown.








Lateral injury radiograph shows dorsal displacement of the fractured navicular with dislocation of both the talonavicular and naviculocuneiform joints. Radiographs tend to underestimate fracture comminution.








Coronal and sagittal CT images, which demonstrate greater detail of the navicular fracture pattern, are shown.








Anteroposterior and lateral postoperative radiographs demonstrating internal fixation of anatomically reconstructed navicular, with supporting bridge plate across medial column of forefoot, are shown. The bridge plate was removed ~ 3 months postoperatively.






Anatomy and Function of Midfoot


General





  • The midfoot includes 5 tarsal bones: Navicular, cuboid, and 3 cuneiforms (medial, 1st; middle, 2nd; and lateral, 3rd).




    • The bases of the metatarsals are also part of the midfoot structure.




  • It forms the transverse arch of the foot and part of the longitudinal arch.



  • The navicular articulates in a mobile relationship with the talus proximally.




    • Motion at the talonavicular joint is essential for normal foot function.




  • The navicular articulate distally with the 3 cuneiforms.




    • Stability at this articulation is more important than flexibility.




  • The cuboid articulates with the anterior process of the calcaneus proximally and with the 4th and 5th metatarsal bases distally.




    • Both proximal and distal articulations are mobile.




  • The cuneiforms articulate with navicular proximally, 1st-3rd metatarsal bases distally, and cuboid laterally (with lateral or 3rd cuneiform).




    • These articulations are rigid.




  • The 2nd metatarsal meets the middle cuneiform in a rigid joint.




    • This articulation is more proximal than the 1st and 3rd joints.



    • This is referred to as the “keystone” of the midfoot.




  • The transverse tarsal, or Chopart, joint is formed by the talonavicular and calcaneocuboid joints.




    • This complex is stiff with hindfoot varus during the toe-off phase of gait.




      • It provides a rigid lever for ambulation.




    • Hindfoot valgus “unlocks” the transverse tarsal joint.




  • Mobility at the transverse tarsal joint is necessary for normal gait.




    • Fusions are not well tolerated.



    • Temporary spanning fixation of the talonavicular and calcaneocuboid joints in the setting of trauma will not be durable.




      • It is often removed once healing of the traumatized foot has occurred.





  • Fixation from 4th or 5th metatarsals into cuboid also restricts normal foot motion and is not well tolerated.




    • If performed, fixation is often removed once healing has occurred in the traumatized foot.




  • The remaining midfoot joints (naviculocuneiform and medial 3 metatarsocuneiform) are relatively stable and nonmobile articulations.




    • They tolerate permanent fixation well.




Midfoot Injuries





  • Although it is possible to fracture a single bone of the midfoot complex, many injuries are more complex.



  • 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.




    • These injuries will affect the stability and structure of the midfoot.




  • The navicular and 3 cuneiforms are packed tightly together and essentially function as a block unit.



  • The 2nd and 3rd metatarsals are tightly connected to each other and to the cuneiforms.



  • There is a proximal transverse intermetatarsal ligament that connects the bases of the 2nd-5th metatarsals.




    • Medially, it runs to the medial cuneiform, not the 1st metatarsal.




  • There is also a distal transverse intermetatarsal ligament that connects the distal end of the 2nd-5th metatarsals.




    • Medially, it inserts on the lateral sesamoids.



    • Again, the 1st metatarsal is not connected.




  • The Lisfranc ligament runs from the medial cuneiform to the base of the 2nd metatarsal.




    • It is mostly a plantar structure.




  • The 1st metatarsal has ligamentous connections to the medial cuneiform.




    • There is no ligamentous connection to the other midfoot joints.




  • The various midfoot injury patterns seen are a reflection of these connections.





Cuneiform Fractures


Introduction





  • Isolated cuneiform fractures are rare.



  • They often occur in conjunction with other midfoot injuries.




    • Lisfranc injuries



    • Cuboid fractures



    • Navicular fractures




  • They most commonly involve the medial (1st) cuneiform.



  • Injuries may occur via a direct mechanism (direct blow) or an indirect mechanism (violent forefoot abduction or adduction).



Evaluation





  • Patients may complain of generalized midfoot pain or may isolate their area of maximal pain to the medial midfoot.




    • Patients often are unable to bear weight on the injured foot.




  • Physical examination may reveal signs of typical midfoot injury, including the following.




    • Edema



    • Ecchymosis



    • Tenderness




  • Skin examination is necessary to rule out impending compromise by bony deformity.




    • This is most likely in the setting of multiple bony or ligamentous injuries.




      • Such as Lisfranc injury





  • Be suspicious of compartment syndrome with severe swelling and high-energy mechanisms.



Treatment





  • Nondisplaced cuneiform fractures, especially without associated midfoot injuries, may be treated conservatively with a well-padded short leg splint.




    • Protected weight bearing is maintained acutely.




  • Displaced cuneiform fractures require open reduction and internal fixation (ORIF).




    • Interfragmentary compression, if possible, may be employed for noncomminuted fractures.




  • Incision is often centered dorsally over the interspace between the 1st and 2nd metatarsal bases and the medial (1st) and middle (2nd) cuneiforms.



  • Comminuted fractures may be stabilized to adjacent, uninjured cuneiforms with intercuneiform screw fixation.



  • Associated midfoot injuries, such as Lisfranc injuries, should also be treated accordingly.



  • Temporary bridge plating may be employed for severely comminuted medial cuneiform fractures.




    • It maintains medial column length.



    • It can bridge from the base of the 1st metatarsal to the navicular or talus.



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Oct 29, 2019 | Posted by in ORTHOPEDIC | Comments Off on Lisfranc and Midfoot Injuries
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