10 - Talus Fracture Flashcards Preview

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

Anatomy

- 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

Blood supply

- Artery of tarsal canal
- Artery of tarsal sinus
- Dorsal neck vessels
- Deltoid branches

SEE DIAGRAMS

3

Artery of tarsal canal

- Supplies the MAJORITY of the talar body

4

Fracture incidence

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

5

Mechanism of injury

- 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

Hawkins classification of talar neck fractures (1970)

- Of the many fracture classifications this one has value
- ***Excellent correlation with prognosis***
- Predictive of AVN rate
- Widely accepted
- 53% Overall AVN incidence

7

Hawkins I

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

8

Hawkins II

- Displaced neck fracture
- Subtalar subluxation
- AVN 20 – 50 %

9

Hawkins III

- 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

Hawkins IV

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

11

Goals of management

- 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

Avascular necrosis (AVN)

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

13

AVN imaging - plain radiographs

o Sclerosis
o Decreases with revascularization

14

AVN imaging - MRI

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

AVN imaging - CAT scan

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

16

AVN imaging - 3D reconstruction

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

AVN treatment - PRE-collapse

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

18

AVN treatment - POST-collapse

o Observation if asymptomatic
o Ankle fusion if symptomatic (Blair fusion if symptomatic)

19

True answer on treatment

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

Post-traumatic arthritis

- Most commonly involves STJ
- Treatment is arthrodesis

21

Talar body fracture

- Treatment strategy and outcomes similar to talar neck fractures
- Medial or Lateral Malleoli Osteotomy frequently required

22

Osteo-chondral defect (OCD)

- 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

Berndt & Hardy Classification

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

Notes

- I and II do better
- III and IV do worse

Maybe read on this a little more?

25

Generalizations ***KNOW THIS***

- Medial – Posterior – Deeper = More bone, less cartilage
- Lateral – Anterior – Shallower (thin and larger, more superficial) = Less bone, more cartilage

26

Hawkins type I treatment

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

Hawkins type III treatment

- Stable fixation for early range of motion

28

Hawkins sign

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

Read up on this a little more

29

MRI study example

- This is a posteromedial view
- Type III because it is completely detached but no displaced

30

Acute or chronic

- Chronic because there is no fluid and ring of white if it is

31

MOST effective treatment for talar dome OCD?

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

32

***Excision and micro-fracture***

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