10 - Talus Fracture Flashcards Preview

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Flashcards in 10 - Talus Fracture Deck (32)
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1
Q

Anatomy

A
  • Surface 60% cartilage
  • No muscular insertions
  • Blood supply in tenuous due to lack of soft tissue attachment
  • Component of 3 joints (STJ, TN, ANKLE)
2
Q

Blood supply

A
  • Artery of tarsal canal
  • Artery of tarsal sinus
  • Dorsal neck vessels
  • Deltoid branches

SEE DIAGRAMS

3
Q

Artery of tarsal canal

A
  • Supplies the MAJORITY of the talar body
4
Q

Fracture incidence

A
  • 2 % of all fractures
  • 6-8% of foot fractures
  • High complication rates (Avascular necrosis, Post-traumatic arthritis)
5
Q

Mechanism of injury

A
  • Hyper-dorsiflexion of the foot on the tibia
  • Neck of talus impinges against anterior distal tibia, causing neck fracture
  • If force continues, talar body dislocates posteromedial around deltoid ligament
  • Previously called “aviator’s astragalus”
  • Usually due to motor vehicle accident or falls from height
6
Q

Hawkins classification of talar neck fractures (1970)

A
  • Of the many fracture classifications this one has value
  • Excellent correlation with prognosis
  • Predictive of AVN rate
  • Widely accepted
  • 53% Overall AVN incidence
7
Q

Hawkins I

A
  • Non-displaced neck fracture
  • Look at the cortex for alignment
  • AVN 0 – 13 %
8
Q

Hawkins II

A
  • Displaced neck fracture
  • Subtalar subluxation
  • AVN 20 – 50 %
9
Q

Hawkins III

A
  • Subtalar and ankle joint dislocated
  • Talar body is tethered around deltoid ligament
  • AVN 83 – 100 %
  • This makes sense because you are tearing
    the blood supply to the talus
10
Q

Hawkins IV

A
  • Includes talonavicular subluxation
  • Rare variant
  • Complex talar neck fractures which do not fit classification can be included
11
Q

Goals of management

A
  • Immediate reduction of dislocated joints to prevent joint and
    soft tissue damage
  • Anatomic fracture reduction to restore function
  • Stable fixation to promote healing and facilitate union
  • Facilitate union
  • Avoid AVN
  • Provide a platform for early active rehabilitation (Move it or lose it)
12
Q

Avascular necrosis (AVN)

A
  • Ischemia
  • Due to arterial interruption
  • Hallmarks on x-ray (increased density) = Sclerosis and Collapse****
13
Q

AVN imaging - plain radiographs

A

o Sclerosis

o Decreases with revascularization

14
Q

AVN imaging - MRI

A

o Very sensitive to decreased vascularity
o T1 = looking at fat, bone with necrosis will lose marrow (fat) so it will look dark
o The MRI often shows patchy areas of bone death

15
Q

AVN imaging - CAT scan

A

o Computed axial tomography
o Better 3D representation
o Confirms displaced vs non-displaced fractures

16
Q

AVN imaging - 3D reconstruction

A

o Can do this image with a CT scan
o Reconstructed CT scan into a 3D view
o Can see the extent of the dislocation very well

17
Q

AVN treatment - PRE-collapse

A
o	Modified WB
o	PTB cast
o	Can take up to 24 months to revascularize 
o	Compliance difficult
o	Efficacy unknown
18
Q

AVN treatment - POST-collapse

A

o Observation if asymptomatic

o Ankle fusion if symptomatic (Blair fusion if symptomatic)

19
Q

True answer on treatment

A

o There is no way to fix dead bone, except to let the body get rid of dead bone and make new bone by restoration of blood supply
o Revascularization process can take a long time – might have modified weight-bearing for up to 2 years

20
Q

Post-traumatic arthritis

A
  • Most commonly involves STJ

- Treatment is arthrodesis

21
Q

Talar body fracture

A
  • Treatment strategy and outcomes similar to talar neck fractures
  • Medial or Lateral Malleoli Osteotomy frequently required
22
Q

Osteo-chondral defect (OCD)

A
  • Not uncommon especially in chronic recurrent sprains and instability (Inverted ankle injury)
  • Talus (Drive shoulder of talus up into tibia and knock off a piece of bone, or Intraarticular fracture)
  • Tibia
23
Q

Berndt & Hardy Classification

A

CORRELATED TO OUTCOME (so actually useful)***

  • I – Small area of compression
  • II – Partially detached OCD
  • III – Fully detached OCD but remains in crater
  • IV – Displaced
24
Q

Notes

A
  • I and II do better
  • III and IV do worse

Maybe read on this a little more?

25
Q

Generalizations KNOW THIS

A
  • Medial – Posterior – Deeper = More bone, less cartilage

- Lateral – Anterior – Shallower (thin and larger, more superficial) = Less bone, more cartilage

26
Q

Hawkins type I treatment

A

On-weight bearing cast for 4-6 weeks followed by removable brace and motion

Percutaneous screw fixation and early motion is also a viable option
o Improved muscle health, tendon health, bone health

Immobilization 
o	Bone gets weaker from demineralization – osteoporosis 
o	Fibrosis of the joint (stiffness) 
o	Atrophy of bone 
o	Devitalized cartilage 

Tendon
o Tendon does not even heal correctly when there is no stress or movement

27
Q

Hawkins type III treatment

A
  • Stable fixation for early range of motion
28
Q

Hawkins sign

A

Subchondral lucency of the talar dome
- If this is present, no worry of AVN

Read up on this a little more

29
Q

MRI study example

A
  • This is a posteromedial view

- Type III because it is completely detached but no displaced

30
Q

Acute or chronic

A
  • Chronic because there is no fluid and ring of white if it is
31
Q

MOST effective treatment for talar dome OCD?

A

Depends on the lesion:
o I = usually conservatively
o II = usually conservatively
o III and IV = usually excise

32
Q

Excision and micro-fracture

A

o Removes the piece and break into the marrow space to release stem cells and bone healing growth factors
o Heals with fibro cartilage, not hyaline cartilage
o Most effective for lesions less than 1.5 cm