Radiology of the Foot

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Radiology of the Foot

• Mark Wahba
• X-Ray rounds
• July 24th, 2003

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Goals

• Approach to radiography of the foot
• Become familiar with a Lisfranc injury
• Become familiar with a Jones fracture

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Outline

• Bones
• Views
• Important Points
• Lisfranc Joint
• Jones fracture
• Films

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The foot

• 28 bones
• 57 articulations

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3 anatomic and functional regions

• Hindfoot talus, calcaneus
• Midfoot navicular, cuboid, cuneiforms
• Forefoot metatarsals, phalanges, sesamoids

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Bones
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Bones
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Accessory Ossification Centres

• Normal
• 30 of population
• Smooth corticated surfaces

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Adequate views

• Anterior-Posterior
• Oblique
• Lateral

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AP
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AP view

• Medial margin of the base of the 2nd metatarsal
  is in line with the medial margin of the middle
  cuneiform
• Base of the 3rd metatarsal is obscured
• View 1st and 2nd MT, medial and middle cuneiform

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AP alignment
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Oblique
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Oblique view

• Medial margin of the base of the 3rd metatarsal
  should be in line with the medial margin of the
  lateral cuneiform
• Base of the 2nd metatarsal is obscured
• View 3,4,5 MT, lateral cunieform, navicular,
  cuboid

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Oblique alignment
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Lateral
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Lateral

• Hindfoot
• Soft tissues
• View articulations CalCub, TN, NCun

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Bohlers Angle

• Draw a line from the posterior aspect of the
  calcaneum to its highest midpoint
• Draw a line from the anterior aspect of the
  calcaneum to its highest midpoint
• Measured angle is from 20-40 degrees

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Bohlers Angle
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Jacques Lisfranc
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Lisfranc Joint

• named for Jacques Lisfranc (1790-1847), a field
  surgeon in Napoleon's army
• described an amputation performed through this
  joint because of gangrene that developed after an
  injury incurred when a soldier fell off a horse
  with his foot caught in the stirrup
• refers to the articulation involving the first
  and second metatarsals with the medial and middle
  cuneiforms

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• Any injury to this area, whether dislocation or
  fracture-dislocation, is termed a Lisfranc injury
• Initially missed 20 of the time
• high risk of chronic pain and functional
  disability if they go unrecognized

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Presentation

• Hx of Direct trauma
• Hx of Indirect trauma force is transmitted to
  the stationary foot so that the weight of the
  body becomes a deforming force by torque,
  rotation or compression
• Pain in midfoot
• Inability to weight bear, especially on toes
• Lisfranc Injury of the Foot A Commonly Missed
  Diagnosis, BURROUGHS et al., American Family
  Physician, July 1998, 58 no. 1 ,p.118

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Why?

• While transverse ligaments connect the bases of
  the lateral four metatarsals, no ligament exists
  between the first and second metatarsal bases. 
  The joint capsule and dorsal ligaments form the
  only minimal support about the Lisfranc joint,
  creating a "weak link" that is prone to injury.
• http//emedhome.com/case-archivedata.cfm?IDcase12
  0701

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• Almost invariably involve metatarsal fractures
• Usually the 2nd metatarsal
• cuboid, cuneiform, navicular occur in 39
• Weight bearing views are useful

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Signs of a Lisfranc injury

• The medial shaft of the 2nd metatarsal should be
  aligned with the medial aspect of the middle
  cuneiform on the AP view.
• The medial shaft of the 3rd metatarsal should be
  aligned with the medial aspect of the lateral
  cuneiform on the oblique view.
• The first metatarsal cuneiform articulation
  should have no incongruency.
• The presence of small avulsed fragments ("fleck
  sign")should be sought in the medial
  cuneiform-second metatarsal space.
• The naviculocuneiform articulation should be
  evaluated for subluxation.
• Should be no "step-off" as each metatarsal shaft
  should never be more dorsal than its respective
  tarsal bone
• http//emedhome.com/case-archivedata.cfm?IDcase12
  0701

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AP
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AP
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Oblique view
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Oblique view
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lateral
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lateral
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Jones Fracture
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Jones Fracture

• Sir Robert Jones described his own fracture of
  the fifth metatarsal in 1902, when he injured
  himself while dancing around a Maypole at a
  military garden party
• at base of 5th metatarsal at metaphyseal-diaphys
  eal junction

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• w/in 1.5 cm distal to tuberosity of 5th
  metatarsal
• Should not be confused w/ more common avulsion
  of 5th metatarsal tuberosity
• An oblique radiograph is essential to accurately
  assess this fracture

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• trauma site corresponds to the area between the
  insertion of the peroneus brevis and tertius
  tendons
• peroneus tertius originates on anterior aspect
  of fibula
• injury occurs when the ankle is plantar flexed
  and a strong adduction force is applied to the
  forefoot

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Jones fracture
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• Ortho follow up
• NWB cast 6-8 weeks
• Notorious for nonunion and needing ORIF b/c of
  low vascularization and high stresses at this site

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5th metatarsal avulsion
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• aka Dancers Fracture
• Conservative treatment 4-6 wks
• Cast, brace, crutches, wooden soled shoe

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• Thought to occur due to stress on the plantar
  aponeurosis causing an avulsion
• Fractures of the Fifth Metatarsal Yu W. D. et al,
  THE PHYSICIAN AND SPORTSMEDICINE - VOL 26 - NO. 2
  - FEBRUARY 98

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Apophysis of 5th metatarsal

• bony outgrowth that has never been entirely
  separated from the bone of which it forms a part
• Found in the skeletally immature

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Stress fracture

• a stress phenomenon at the metaphyseal-diaphyseal
  junction
• severe intramedullary sclerosis, profound
  thickening of both the medial and lateral
  cortices, lucency in the lateral cortex

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• Treat conservatively or operatively depending on
  activity level

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Films
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Lisfranc fracture/dislocation
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Calcaneal fractures

• Most commonly fractured tarsal bone
• 25 have other lower extremity injury
• thoracolumbar fractures occur in 10 of patients
  with calcaneal fractures

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1st metatarsal

• Lisfranc injury

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Subtalar Dislocation

• Disruption of talocalcaneal and talonavicular
  joints
• No disruption of the tibiotalar joint
• Closed reduction, ortho consult

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Fracture Talus

• 2nd most common tarsal fracture
• Mechanism plantar or dorsi flexion plus
  inversion
• High incidence of complications AVN

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Talus fractures

• talar neck
• excessive dorsiflexion of the ankle
• stepping on brakes in MVA, snowboarders
• AVN, subchondral collapse, degenerative arthritis
• Need ortho consult in ED

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Fracture of Navicular and Cuboid

• Navicular high risk of AVN (similar to
  scaphoid)
• Most can have ortho F/U but if intra-articular
  should be seen in ED

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Lisfranc dislocation
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Jones fracture
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Lisfranc fracture/dislocation
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Fracture calcaneus
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Lisfranc injury
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Summary

• Know what to look at on each view
• Know what to look for in Lisfranc Injuries
• Know what to look for in a Jones fracture

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end
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References

• Accident Emergency Radiology A Survival Guide,
  Raby et al, 2001 Harcourt Publishers ltd Toronto
  Chapter 13
• Pitfalls in Radiographic Interpretation, Part 2,
  Michelle Lin, MD, http//emedhome.com/archives-dat
  a.cfm?IDnews042803Typenews
• Clinical Cases, Emedhom.com, http//emedhome.com/c
  ase-archivedata.cfm?IDcase120701
• Lisfranc Injury of the Foot A Commonly Missed
  Diagnosis, BURROUGHS et al., American Family
  Physician, July 1998, 58 no. 1 ,p.118
• Rosens Emergency Medicine Concepts and Clinical
  Practice 5th ed., Marx et al. Mosby, Toronto,
  2002 chapter 51
• Wheeless' Textbook of Orthopaedics,
  http//www.ortho-u.net/Welcome.html
• Fractures of the Proximal Fifth Metatarsal,
  STRAYER et al. American Family Physician, May
  1999, 59 no.9 p.2516
• Lisfranc Fracture Dislocation, Early J. S.
  http//www.emedicine.com/orthoped/topic511.htm
• Fractures of the Fifth Metatarsal Yu W. D. et al,
  THE PHYSICIAN AND SPORTSMEDICINE - VOL 26 - NO. 2
  - FEBRUARY 98
• Pitfalls in the Radiologic Evaluation of
  Extremity TraumaPart II. The Lower Extremity,
  SHEARMAN C. S. et al, American Family Physician
  March 1998