Transcript Radiology of the Foot

Radiology of the Foot
Mark Wahba
X-Ray rounds
July 24th, 2003
Goals
• Approach to radiography of the foot
• Become familiar with a Lisfranc injury
• Become familiar with a Jones fracture
Outline
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Bones
Views
Important Points
Lisfranc Joint
Jones fracture
Films
The foot
• 28 bones
• 57 articulations
3 anatomic and functional
regions
• Hindfoot: talus, calcaneus
• Midfoot: navicular, cuboid, cuneiforms
• Forefoot: metatarsals, phalanges, sesamoids
Bones
Bones
Accessory Ossification Centres
• Normal
• 30% of population
• Smooth corticated surfaces
Adequate views
• Anterior-Posterior
• Oblique
• Lateral
AP
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
AP alignment
Oblique
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
Oblique alignment
Lateral
Lateral
• Hindfoot
• Soft tissues
• View articulations: CalCub, TN, NCun
Bohler’s 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
Bohler’s Angle
Jacques Lisfranc
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
• 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
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
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Lisfranc Injury of the Foot: A Commonly Missed Diagnosis, BURROUGHS et al., American Family
Physician, July 1998, 58 no. 1 ,p.118
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.”
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http://emedhome.com/case-archivedata.cfm?ID=case120701
• Almost invariably involve metatarsal
fractures
• Usually the 2nd metatarsal
• # cuboid, cuneiform, navicular occur in
39%
• Weight bearing views are useful
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?ID=case120701
AP
AP
Oblique view
Oblique view
lateral
lateral
Jones Fracture
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-diaphyseal junction
• 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
• 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
Jones fracture
• 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
5th metatarsal avulsion #
• aka Dancer’s Fracture
• Conservative
treatment 4-6 wks
• Cast, brace, crutches,
wooden soled shoe
• 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
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
Stress fracture
• a stress phenomenon
at the metaphysealdiaphyseal junction
• “severe intramedullary
sclerosis, profound
thickening of both the
medial and lateral
cortices, lucency in the
lateral cortex”
• Treat conservatively or
operatively depending
on activity level
Films
Lisfranc fracture/dislocation
Calcaneal fractures
• Most commonly fractured tarsal bone
• 25% have other lower extremity injury
• thoracolumbar fractures occur in 10% of
patients with calcaneal fractures
1st metatarsal #
• Lisfranc injury
Subtalar Dislocation
• Disruption of talocalcaneal and
talonavicular joints
• No disruption of the tibiotalar joint
• Closed reduction, ortho consult
Fracture Talus
• 2nd most common tarsal fracture
• Mechanism: plantar or dorsi flexion plus
inversion
• High incidence of complications: AVN
Talus fractures
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talar neck
excessive dorsiflexion of the ankle
stepping on brakes in MVA, snowboarders
AVN, subchondral collapse, degenerative
arthritis
• Need ortho consult in ED
Fracture of Navicular
and Cuboid
• Navicular # high risk of AVN (similar to
scaphoid)
• Most can have ortho F/U but if intraarticular should be seen in ED
Lisfranc dislocation
Jones fracture
Lisfranc fracture/dislocation
Fracture calcaneus
Lisfranc injury
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
end
References
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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/archivesdata.cfm?ID=news042803&Type=news
Clinical Cases, Emedhom.com, http://emedhome.com/case-archivedata.cfm?ID=case120701
Lisfranc Injury of the Foot: A Commonly Missed Diagnosis, BURROUGHS et al., American Family
Physician, July 1998, 58 no. 1 ,p.118
Rosen’s 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 Trauma:Part II. The Lower Extremity,
SHEARMAN C. S. et al, American Family Physician March 1998