Fractures of Talus - Orthopaedic Trauma - Lecture Slides, Slides of Orthopedics

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Fractures of the Talus and

Subtalar Dislocations

Outline:

Talar Neck Fractures

• Anatomy
• Incidence
• Imaging
• Classification
• Management
• Complications

Talar body, head and process fractures

Subtalar dislocations

• Classification
• Management
• Outcomes

Anatomy

• Surface 60% cartilage
• No muscular insertions

Incidence

• 2 % of all fractures
• 6-8% of foot fractures
• Importance due to high

complication rates

• avascular necrosis
• post-traumatic arthritis
• malunion

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

Injury Mechanism

• Previously called “aviator’s astragalus”
• Usually due to motor vehicle accident or falls from height
• Approximately 50 % have multiple traumatic injuries

Biomechanics

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

Canale View

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

Canale View

CT Scan

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

MRI Scan

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

Talar Neck Fractures: Classification

• Hawkins 1970
• Predictive of AVN rate
• Widely used

Hawkins 1

• I: undisplaced

• AVN 0 – 13 %

Hawkins 2

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

Hawkins 3

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

• AVN 83 – 100 %

Hawkins 4

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

Classification:

• Comminution:
• An important additional predictor of results,

especially regarding:

• Malunion
• Subtalar joint arthritis

Goals of Management

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

Treatment of Talar Neck Fractures

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

upon personality of fracture

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

Hawkins I Fracture

Options:

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

Hawkins II, III, and IV Fractures:

• Results dependent upon development of

complications

• Osteonecrosis
• Malunion
• Arthritis

Case Example

• 29 yo male

• ATV rollover

• Isolated injury

LLE

Diagnosis

• Hawkins’ 3 talar neck fracture
• Associated comminution, probably involving

medial column and subtalar joint

Controversies for this Case:

• Surgical timing
• Closed reduction
• Surgical approach
• Fixation

Surgical Timing

• Emergent reduction of dislocated joints
• Allow life threatening injuries to take priority

and resuscitate adequately first