Fractures of the Lateral Process of the Talus: A Diagnostic Challenge

1
Fractures of the Lateral Process of the Talus
A Diagnostic Challenge

• A Tutorial for Optimizing Detection
• Julia Crim, MD
• Bradley Hale, MD
• University of Utah

2
Lateral Process Talus Fractures

• Fractures can be subtle and difficult to see on
  plain radiographs.
• Fractures and their sequelae can lead to
  long-term debility.
• Fractures are more common than previously
  thought.
• A systematic approach to evaluation improves
  identification.

3
Objectives of this presentation.

• 1. Review pertinent anatomy.
• 2. Review common mechanisms and patient
  presentation.
• 3. Review imaging techniques including
  radiographs, CT and MRI.
• 4. Increase awareness of subtle signs associated
  with these fractures.

4
Lateral Process of Talus
The superior margin of the lateral process is
part of the lateral gutter of the ankle joint.
Posterior subtalar joint
The inferior margin of the lateral process forms
the anterior portion of the posterior subtalar
joint.
Calcaneus
Lateral process
As part of both the tibiotalar and posterior
subtalar joints, the lateral process is
important in many complex motions including
inversion, eversion, dorsiflexion, plantarflexion
and gliding.
5
Radiograph of Lateral Process of the Talus
Talus
Calcaneus
6
Lateral Process from Above
7
Lateral Process on Coronal CT
Lateral gutter
Posterior subtalar joint
8
Radiograph of the Lateral Process
Tibia
Fibula
Talus
Lateral process
AP
mortise
9
Mechanism of Injury

• Fracture occurs from inversion and dorsiflexion
  of foot .
• Patients often present with ankle sprain.
• Lateral process transmits compression force from
  tibia to calcaneus.

10
Common Causes of Fracture

• Snowboarding
• Fall from a height
• Soccer
• Occasionally MVA

11
Fracture Incidence

• Uncommon?
• Lateral process fractures first reported 1942.
• Mukherjee (1974) reported that lateral process
  fractures accounted for less than 1 of 1500
  ankle injuries reviewed.
• Or undetected?
• Hawkins (1965) 26 of talus fractures
• 40-50 of lateral process fractures not detected
  at time of injury (Hawkins, Mukherjee, Mills and
  Horne)

12
Lateral Process Fracture

• Divided into three types
• May be displaced or non-displaced

Type 2 Fracture through the base of the process
Type 3 Comminuted
Type 1 - Chip fracture off tip of process
13
Fracture Treatment

• Cast
• Screw fixation
• Excision of comminuted fragments

14
Prognosis of Fracture

• Good with early ORIF
• Poor with casting or delayed ORIF

15
Prospective study of fx treatment

• 23 intra-articular fractures with mean follow up
  of 24 months.
• Functional outcome rating 0-100
• 4 underwent early ORIF 3 rated 100, 1 rated 93
• 19 patients were casted
• 4 rated 100
• 15 rated 65-95
• 11 complained of stiffness and/or pain with
  exercise
• 4 unable to do activities of daily living

• Paul CC, Janes PC. Snowboarders talus fx
  Skiing trauma and safety intl symposium 1996

16
Potential Complications

• Nonunion
• Osteoarthritis of subtalar joint
• Some may need subtalar arthrodesis

17
Recommended Imaging Lateral Process Fx

• AP, Mortise, Lateral
• The fracture may be visible on only one view
• Radiographs underestimate extent of fracture
• Brodens with plantarflexion
• Internal rotation neutral flexion
• Lateral tomography (obsolete)
• CT, including reconstructions
• MRI

18
Radiographic findings

• Visible fracture line or cortical step-off.
• Non-visualization or decreased density of the tip
  of the lateral process.
• Displacement or rotation.
• Lateral soft tissue swelling, typically lower
  than seen in ankle sprain without fracture.

19
Pitfalls in Detection

• Fracture may be visible on only one view.
• Radiographs may underestimate fracture.
• If suspicious, go to CT or MRI.

20
Radiographic finding 1Cortical step-off
22 year old female soccer player reports twisting
ankle during the game
Normal lateral process
21
Radiographic finding 1Cortical step-off
22 year old female soccer player reports twisting
ankle during the game
An oblique fracture with cortical step-off is
seen through the anterior margin (blue arrow) of
the lateral process. A subtle lucency is visible
at the inferior margin (green arrow).
Normal
22
Radiographic finding 2 Non-visualization of the
tip of the process.
A young snowboarder.
Normal lateral process
The tip of the lateral process is indistinct and
poorly visualized
23
Radiographic finding 3Displacement
Another snowboarder (snowboarding can be
dangerous!)
Displaced fragment seen on both the AP (inferior
displacement) and lateral projection (anterior
displacement).
24
Radiographic finding 4Soft tissue swelling
Fracture
STS
Fracture
STS
Radiographs from two separate patients with
lateral process fractures. Note that soft tissue
swelling is present laterally, but is more
inferior than is typically seen in an ankle
sprain or distal fibular fracture.
25
Pitfall in detection Fracture visible on only 1
view
Fell off ladder.
This fracture (which was initially missed) is
seen only on the anterior projection where
cortical irregularity is identified.
26
Pitfall in detection Radiographs may
underestimate extent of fracture. CT is
recommended for any fracture larger than a flake.
Radiographs show fracture which appears to be
through the tip of the process. However, CT
(including reconstructions) shows the fracture to
be much larger, extending into the base of the
process. The posterior subtalar joint is
extensively disrupted.
27
Improving detection If suspicious, MRI may be
helpful.
Sag STIR
Initial radiographs interpreted as normal.
Patient continued to have pain. MRI clearly
shows fracture through the base of the process.
28
How accurate are radiographs in diagnosis of
lateral process fractures?
29
Utah Series

• 14 intra-articular lateral process fractures over
  8 month interval
• Patient age range 18-35
• 2 fractures initially missed by the resident
  physician, but detected on radiographs by the
  attending 12 detected acutely on radiographs by
  the resident.
• 7 had other associated fractures
• 8 had CT, 1 had MRI

30
Views on which fractures were visible

• Lateral only 3 (including 1 missed fx)
• Readily visible on lateral but difficult on AP 2
• Lateral and AP 5
• Lateral and mortise 1
• AP only 1 (missed)
• Seen on all views 2

31
Utah Series Associated Fractures

• 5 talus
• 1 body
• 2 neck
• 1 head of talus
• 1 posterior process talus
• 1 EDB origin avulsion
• 1 nondisplaced central calcaneus
• 1 pilon (seen on CT only)
  
  
  

32
Final Review

• In reviewing this presentation we hope you were
  able to
• Become more familiar with the anatomy of the
  talus
• Become more aware of the significance of lateral
  process fractures
• Review important signs of this fracture
• Better understand pitfalls and how to minimize
  them

33
References

• Hawkins LG. (1965) Fractures of the lateral
  process of the talus. J Bone Joint Surg.
  47A275.
• Heckman JC, McLean MR. (1985) Fractures of the
  lateral process of the talus. Clin Orthop
  199108-113.
• Higgins TF, Baumgaertner, MR. (1999) Diagnosis
  and treatment of fractures of the talus A
  comprehensive review of the literature. Foot
  Ankle Int. 20(9)595-604.
• Mills HJ, Horne G. (1987) Fractures of the
  lateral process of the talus. Aust N.Z. J. Surg.
  57643-646.
• Mukherjee SK, Pringle RM, Baxter AD. (1974)
  Fractures of the lateral process of the talus.
  J. Bone Joint Surg. 56B263
• Paul CC, Janes PC. Snowboarders talus fx
  Skiing trauma and safety intl symposium 1996.

34
Thank You!