Study Guide

Foot Dislocations (Lisfranc and Subtalar)

Key Points:

Description:

Lisfranc injuries range from purely ligamentous to severe fracture-dislocations of the forefoot.  The tarsometatarsal joints have intrinsic stability due to the recessed base of the 2nd metatarsal and the “Roman arch” configuration of the middle three metatarsals as well as the Lisfranc ligament, which runs from the base of the 2nd metatarsal to the medial cuneiform.(Kay, 2001) Diastasis frequently occurs between the 1st and 2nd metatarsals, but all 5 rays can be involved.  If all rays displace in the same direction, it is a homolateral injury vs. a divergent injury in which the 1st ray displaces medially and the lateral rays displace laterally.(Kay, 2001)  The Hardcastle Classification divides Lisfranc 
injuries into three types based on displacement(Crawford, 2010; Hardcastle 1982):

Type A: total incongruity of the entire metatarsal joint in a single plane

Type B: partial incongruity of the joint caused by medial displacement of the first metatarsal or lateral displacement of the lateral metatarsals (most common in children)

Type C: divergent pattern with the first metatarsal displaced medially and the lateral metatarsals displaced laterally

Subtalar or peritalar dislocations are uncommon injuries in children.(Crawford, 2010) The most common type is a medial dislocation caused by forced inversion of the foot.  The talus remains in the ankle mortise while the bones of the forefoot dislocate medially.  Less common is a lateral dislocation, which is caused by forced eversion of the foot.(Crawford, 2010)

Epidemiology:

Lisfranc Injuries are rare in children.  The largest series in the literature includes 18 children (Wiley, 1981) and most other reports are limited to isolated cases.  This injury is more common in older children, but injuries in children as young as 3 have been reported.(Kay, 2001) 
  
Subtalar dislocations are rare.  They account for 4% of all pediatric talar fractures and dislocations. (Kay, 2001; Dimentburg, 1993)  These injuries occur most frequently in young adult males. (Crawford, 2010)

Clinical Findings:

Lisfranc injuries can be subtle and are therefore frequently missed.  Some injuries may present with mild pain and swelling at the base of the 1st and 2nd metatarsals.  There may be ecchymosis on the plantar aspect of the foot.(Crawford, 2010; Ross, 1996) In more severe injuries, there will be significant swelling and bruising.   Abduction and pronation of the forefoot while holding the hindfoot fixed will illicit pain after a Lisfranc injury.(Crawford, 2010; Myerson, 1986)

In a subtalar dislocation the foot will look deformed with severe soft tissue swelling.  The talar head may be palpable laterally in a medial dislocation.(Crawford, 2010)

Imaging Studies:

For Lisfranc injuries, weight-bearing AP, lateral and oblique views of the foot are preferred whenever possible as subtle injuries may not be seen on non-weight bearing films.  On the AP radiograph, the lateral border of the 1st metatarsal should line up with the lateral border of the medial cuneiform and the medial border of the second metatarsal should line up with the medial border of the middle cuneiform.  On the oblique, the medial border of the fourth metatarsal should line up with the medial border of the cuboid.(Crawford, 2010)  Disruption of these lines or diastasis >2mm between the base of the 1st and 2nd metatarsals represents a Lisfranc Injury.  An isolated fracture of the base of the 2nd 
metatarsal should alert the practitioner to the presence of injury to the Lisfranc complex.(Kay, 2001)   A “fleck sign” represents a small avulsion fracture of the base of 2nd metatarsal form the Lisfranc ligament.  Contralateral radiographs are helpful for comparison in subtle injuries.  CT or MRI can be used in cases where an injury is suspected but not confirmed by plain radiographs.(Crawford, 2010; Rosenberg, 1995)

Radiographic evaluation of subtalar dislocations may demonstrate an “empty navicular” sign.  The talar head will no longer be seen articulating with the navicular. CT scan can be performed after closed reduction to evaluate for evidence of other fractures.(Crawford, 2010)

Treatment:

Lisfranc injuries with <2mm of displacement can placed in a bulky dressing for 2-3 days to allow swelling to decrease, a well-padded splint or a well-padded short leg cast placed to accommodate swelling. Some studies recommend immobilization in a short-leg non-weight bearing cast  for an additional 4-6 weeks.(Kay, 2001; Crawford, 2010; Wiley, 1981)Some practitioners may choose to allow weight bearing in a short leg cast for the last 2 weeks of immobilization. Other studies recommend a short leg walking cast for approximately 4-6 weeks until all pain and tenderness has resolved.(Buoncristiani, 2001) Displaced injuries require operative management to obtain and maintain anatomic reduction of the tarsometatarsal joint complex.(Kay, 2001) Closed reduction can be attempted in 
the operating room with traction on the forefoot.  If anatomic reduction is achieved by closed means, percutaneous fixation can be performed using Kirschner wires in younger children and cannulated screws in older children. (Kay, 2001)  If closed reduction does not produce anatomic reduction of the 
Lisfranc complex with <2mm of displacement, then open reduction and internal fixation must be performed. (Kay, 2001; Crawford, 2010) Often there will be osteo-cartilaginous fragments interposed within the joint and these must be removed in order to achieve anatomic reduction. (Kay, 2001) 

For subtalar dislocations, attempted closed reduction with sedation should be performed.  Knee flexion will relax the Achilles tendon to assist with reduction.  Stable reductions are followed by a period of immobilization to allow the soft tissues to heal.  If the reduction is not stable, percutaneous Kirschner wire stabilization may be necessary.  Irreducible dislocations may have soft-tissues interposition (most commonly the tibialis posterior tendon).  In this situation, an open reduction through a anteromedial approach must be performed.  Unstable dislocations and irreducible dislocations require longer periods of immobilization. (Crawford, 2010)

Complications:

The most common complication after Lisfranc injury is pain from posttraumatic arthritis either from a missed injury, loss of reduction or non-anatomic reduction. (Crawford, 2010; Wiley, 1981; Buoncristiani, 2001) In rare instances this complication may require further treatment with arthrodesis. 

After subtalar dislocation posttraumatic arthritis and decreased subtalar motion are the most common complications.(Dimentberg, 1993)

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References:

  1. Buoncristiani AM, Manos RE, Mills WJ. Plantar-flexion tarsometatarsal joint injuries in children. Journal of Pediatric Orthopaedics. 2001;21(3):324–327.
  2. Crawford H. Fractures and Dislocations of the Foot. In: Flynn JM, Skaggs DL, Waters PM, eds. Rockwood and Wilkins' Fractures in Children. 8 ed. Lippincott Williams & Wilkins; 2010. 
  3. Dimentberg R, Rosman M. Peritalar dislocations in children. Journal of Pediatric Orthopaedics. 1993;13(1):89–93.
  4. Kay RM, Tang CW. Pediatric foot fractures: evaluation and treatment. J Am Acad Orthop Surg. 2001;9(5):308–319.
  5. Hardcastle PH, Reschauer R, Kutscha-Lissberg E, Schoffmann W. Injuries to the tarsometatarsal joint. Incidence, classification and treatment. J Bone Joint Surg Br. 1982;64(3):349–356.
  6. Myerson MS, Fisher RT, Burgess AR, Kenzora JE. Fracture dislocations of the tarsometatarsal joints: end results correlated with pathology and treatment. Foot Ankle. 1986;6(5):225–242.
  7. Rosenberg GA, Patterson BM. Tarsometatarsal (Lisfranc's) fracture-dislocation. Am J Orthop. 1995;Suppl:7–16. 
  8. Ross G, Cronin R, Hauzenblas J, Juliano P. Plantar ecchymosis sign: a clinical aid to diagnosis of occult Lisfranc tarsometatarsal injuries. J Orthop Trauma. 1996;10(2):119–122.
  9. Wiley JJ. Tarso-metatarsal joint injuries in children. Journal of Pediatric Orthopaedics. 1981;1(3):255–260.
  10. Wiley JJ. The mechanism of tarso-metatarsal joint injuries. J Bone Joint Surg Br. 1971;53(3):474–482.

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