David Sanders MD, MSc, FRCSC

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Fractures of the Talus and Subtalar Dislocations

• David Sanders MD, MSc, FRCSC
• London Health Sciences Centre
• University of Western Ontario
• London, Ontario, Canada
• Created March 2004 Revised August 2006

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Outline

• Talar Neck Fractures
• Anatomy
• Incidence
• Imaging
• Classification
• Management
• Complications

• Talar body, head and process fractures
• Subtalar dislocations
• Classification
• Management
• Outcomes

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Anatomy

• Surface 60 cartilage
• No muscular insertions

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Blood Supply

• Arterial supply
• Artery of tarsal canal
• Artery of tarsal sinus
• Dorsal neck vessels
• Deltoid branches

medial
lateral
Inferior view of talus, showing vascular
anastomosis
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Vascularity

• Artery of tarsal canal supplies majority of talar
  body

Side View
Top View
Deltoid Branches
Superior Neck Vessels
Artery of Tarsal Canal
Posterior tubercle vessels
Artery of Tarsal Canal
Superior Neck Vessels
Posterior tubercle vessels
Artery of Tarsal Sinus
Artery of Tarsal Sinus
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Incidence

• 2 of all fractures
• 6-8 of foot fractures
• Importance due to high complication rates
• avascular necrosis
• post-traumatic arthritis
• malunion

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Mechanism of Injury

• Hyperdorsiflexion of the foot on the leg
• Neck of talus impinges against anterior distal
  tibia, causing neck fracture
• If force continues
• talar body dislocates posteromedial
• often around deltoid ligament

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Injury Mechanism

• Previously called aviators astragalus
• Usually due to motor vehicle accident or falls
  from height
• Approximately 50 have multiple traumatic
  injuries

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Biomechanics

• Theoretical shear force across talar neck
• 1200 N during active motion
• Swanson 1992

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Imaging

• Complex 3-D structure
• Multiple plain film orientations

Canale View
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Canale View

• Ankle plantarflexion
• 15 degree pronation
• Tube 15 degree off vertical

Canale View
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CT Scan

• Can be a useful assessment tool
• Confirms truly undisplaced fractures
• Demonstrates subtalar comminution, osteochondral
  fractures

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MRI Scan

• Primary role in talus injuries is to assess
  complications, especially avascular necrosis
• May be poor quality if extensive hardware present

Zone of osteonecrosis following distribution of
Artery of Tarsal Canal
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Talar Neck Fractures Classification

• Hawkins 1970
• Predictive of AVN rate
• Widely used

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Hawkins 1

• I undisplaced
• AVN 0 13

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Hawkins 2

• Displaced fracture
• Subtalar subluxation
• A) fracture line enters subtalar joint
• B) subtalar joint intact
• AVN 20 50

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Hawkins 3

• Subtalar and ankle joint dislocated
• Talar body extrudes around deltoid ligament
• AVN 83 100

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Hawkins 4

• Incorporates talonavicular subluxation
• Rare variant
• Complex talar neck fractures which do not fit
  classification can be included

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Classification

• Comminution
• An important additional predictor of results,
  especially regarding
• Malunion
• Subtalar joint arthritis

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Goals of Management

• Immediate reduction of dislocated joints
• Anatomic fracture reduction
• Stable fixation
• Facilitate union
• Avoid complications

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Treatment of Talar Neck Fractures

• Emergent reduction of dislocated joints
• Stable internal fixation
• Choice of fixation and approach depends upon
  personality of fracture

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Treatment of Talar Neck Fractures

• Post operative rehabilitation
• Sample protocol
• Initial immobilization, 2-6 weeks depending upon
  soft tissue injury and patient factors, to
  prevent contractures and facilitate healing
• Non weight-bearing, Range of Motion therapy until
  3 months or fracture union

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Hawkins I Fracture

• Options
• Non-Weight-Bearing Cast for 4-6 weeks followed by
  removable brace and motion
• Percutaneous screw fixation and early motion

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Hawkins II, III, and IV Fractures

• Results dependent upon development of
  complications
• Osteonecrosis
• Malunion
• Arthritis

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Case Example

• 29 yo male
• ATV rollover
• Isolated injury LLE

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(No Transcript)
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Diagnosis

• Hawkins 3 talar neck fracture
• Associated comminution, probably involving medial
  column and subtalar joint

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Controversies for this Case
????

• Surgical timing
• Closed reduction
• Surgical approach
• Fixation

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Surgical Timing

• Emergent reduction of dislocated joints
• Allow life threatening injuries to take priority
  and resuscitate adequately first

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Closed Reduction?

• May be very useful, particularly if other life
  threatening injuries preclude definitive surgery
• Difficult in Hawkins 3 and 4 injuries

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Closed Reduction Technique

• Adequate sedation
• Flex knee to relax gastrocs
• Traction on plantar flexed forefoot to realign
  head with body
• Varus/valgus correction as necessary

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Closed Reduction Example
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External Fixation

• Limited roles
• Multiply injured patient with talar neck fracture
  in whom definitive surgery will be delayed
• Temporizing measure to stabilize reduced joints

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Surgical Approaches Options

• 1 incision techniques
• Anteromedial or
• Anterolateral
• Problem difficult to visualize talar neck and
  subtalar joint without significant soft tissue
  stripping
• Benefit potentially less skin injury

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Surgical Approaches Options

• 2 incision technique
• Anteromedial and direct lateral
• Problem 2 skin incisions, close together
• Benefit excellent fracture visualization at
  critical sites of reduction and subtalar joint

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1st Approach Anteromedial

• Medial to TA and Anterior Compartment contents
• Make incision more posterior for talar body
  fractures to facilitate medial malleolar
  osteotomy

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1st Approach Anteromedial

• Provides view of neck alignment and medial
  comminution

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2nd Approach Direct Lateral

• Tip of Fibula directly anterior
• Mobilize EDB as sleeve
• Protect sinus tarsi contents

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2nd Approach Direct Lateral

• Visualizes Anterolateral alignment and subtalar
  joint
• Facilitates Placement of Shoulder Screw

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Protect the Skin Post Op
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Fixation Options

• Stable Fixation to allow early motion is the goal
• 1200 N stress across talar neck during early
  motion
• (Swanson JBJS 1992)

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Surgical Tactics Fixation

• Anterior
• Partial threaded screws
• Fully threaded screws
• Mini-fragment plates
• Posterior
• Lag screws

Implant selection depends upon injury, degree of
comminution, bone quality
But should be strong enough to withstand motion
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Posterior to Anterior Fixation

• stronger than anterior to posterior fixation with
  2 screws
• Able to withstand the theoretical shear force of
  active motion (Swanson, JBJS 1992)
• Screws perpendicular to fracture site

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Anterior Screw Fixation

• Non-comminuted fractures
• Easy to insert under direct visualization and no
  cartilage damage
• Displaced type 2 3 A-P screws including medial
  buttress fully threaded cortical screws and
  lateral shoulder screws

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Anterior Screw Fixation

• Comminuted fractures
• Buttress screw comminuted column compression
  screws through non-comminuted column
• Mini-fragment screws for osteochondral fragments
• Consider Titanium for MRI

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Anterior Plate Fixation

• Comminuted fractures
• Medial and / or lateral mini-fragment plates

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Complications

• AVN
• Malunion

• Nonunion
• Arthritis

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AVN Incidence after Talus Fracture

• Canale (1972)
• I 15
• II 50
• III 85
• IV 100

• Behrens (1988)
• Overall 25
• Ebraheim/Stephen (2001)
• Overall 20

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AVN Diagnosis

• Hawkins Sign Xray finding 6-8 weeks post
  injury
• Presence of subchondral lucency implies
  revascularization

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AVN Imaging

• Plain radiographs sclerosis common, decreases
  with revascularization
• MRI very sensitive to decreased vascularity

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AVN Treatment

• Precollapse
• Modified WB
• PTB cast
• Compliance difficult
• Efficacy unknown

• Postcollapse
• Observation
• Blair fusion if symptomatic

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Malunion Incidence

• Common up to 40
• Most often Varus

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Malunion Diagnosis

• Varus hindfoot, midfoot supination on clinical
  exam
• Dorsal malunion on Xray

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Malunion

• Mechanical effects known
• gt 3 degrees decreased ROM
• (Daniels TR, JBJS 1996)
• gt 2mm altered subtalar contact forces
  (Sangeorzan
• J Orthop Res 1992)

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Clinical Effect of Malunion

• Malunion
• More pain
• Less satisfaction
• Less ankle motion
• Worse functional outcome

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Malunion Rx

• Calcaneus osteotomy
• Possible midfoot osteotomy
• Tendo Achilles Lengthening

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Post Traumatic Arthritis

• Incidence of post-traumatic arthritis
• 30-90

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Post-Traumatic Arthritis

• Most commonly involves Subtalar joint
• Rx Arthrodesis

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Nonunion

• Uncommon, even with AVN
• Delayed Union very common
• Frequently results in late malalignment

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Talar Body Fractures

• Treatment strategy and outcomes similar to talar
  neck fractures
• Medial or Lateral Malleolar Osteotomy frequently
  required

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Medial Malleolar Osteotomy

• Predrill and pretap malleolus
• Osteotomy aims for medial corner of mortise
• Osteotome to crack cartilage helps avoid mortise
  malalignment

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Talar Body Fibula Fracture

• Visualize body through the fibula fracture

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Talar Body Case Example

• 58 year old female
• 4 week old fracture
• Missed initially

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Case, contd

• Extensive comminution into subtalar joint
• Fragments very small

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Selected Rx Primary Arthrodesis
Tricortical bone graft to reconstitute talar
height
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Osteochondral Injuries

• Frequently encountered with talus neck and body
  fractures
• Require small implants for fixation
• Excise if unstable and too small to fix

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Osteochondral Injuries
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Osteochondral Fragment Repair
Large fragment repaired, small fragment excised
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Talar Head and Process Fractures

• Treat according to injury
• Operate when associated with joint subluxation,
  incongruity, impingement or marked displacement
• Fragments often too small to fix and require
  excision

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Case Example Talar Head Fracture

• Talar head injury
• Subtle on plain x-ray

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Talar Head Fracture, continued

• CT demonstrates subtalar injury and subluxation

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Treatment of Talar Head Fracture

• Required 2 incisions to debride subtalar joint
  from lateral approach, and reduce / stabilize
  fracture from medial side

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Lateral Process Example

• Usually require CT scan
• Often excised due to size of fragments
• Difficult to achieve union

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Lateral Talar Process Fractures

• Snowboarders fracture
• Mechanism may occur from inversion (avulsion
  injury) or eversion and axial loading (impaction
  fracture)
• Often misdiagnosed as ankle sprain
• Best results if treated early, either by
  immobilization, ORIF or fragment excision
• If diagnosed late consider fragment excision as
  attempts to achieve union often fail

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Posterior Talar Process Fracture

• 2 components medial and lateral tubercle
• Groove for FHL tendon separates the two tubercles
• Differentiate fracture from os trigonum well
  corticated, smooth oval or round structure

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Posterior Talar Process Fractures

• Medial tubercle fracture Cedells fracture
• Lateral tubercle Shepherds fracture
• Treatment immobilize or excise

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Subtalar Dislocations

• Spectrum of injuries
• Relatively Innocent
• Very Disabling

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Classification

• Usually based upon direction of dislocation
• Medial dislocation 85 , low energy
• Lateral dislocation 15 , high energy

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Other Important Considerations
All have prognostic significance

• Open vs Closed
• High or low energy mechanism
• Stable or unstable post reduction

• Reducible by closed means or requiring open
  reduction
• Associated impaction injuries

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Important Distinction

• Total talar dislocation, or pan talar dislocation
• Results from continuation of force causing
  subtalar dislocation
• High risk of AVN, usually open, poor prognosis

Open pantalar dislocation with skin loss showing
Imperfect reduction Result was AVN and
pantalar fusion
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Management of Subtalar Dislocation

• Urgent Closed reduction
• Adequate sedation
• Knee flexion
• Longitudinal foot traction
• Accentuate, then reverse deformity
• Successful in up to 90 of patients

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Open Reduction

• More likely after high energy injury
• More likely with lateral dislocation
• Cause
• soft tissue interposition (Tib post, FHL,
  extensor tendons, capsule)
• bony impaction between the talus and navicular

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Rehabilitation

• Stable injuries
• 4 weeks immobilization
• Physio for mobilization
• Unstable injuries
• Usually dont require internal fixation once
  reduction achieved

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Outcome of Subtalar Dislocations

• Less benign than previously thought
• Subtalar arthritis
• Up to 89 radiographically
• Symptomatic in up to 63
• Ankle and midfoot arthritis less common

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Summary

• Talar Neck Fractures
• Anatomy
• Incidence
• Imaging
• Classification
• Management
• Complications

• Talar body, head and process fractures
• Subtalar dislocations
• Classification
• Management
• Outcomes

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