Talus Fracture Flashcards

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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)
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2
Q

Blood supply

A
  • Artery of tarsal canal- Artery of tarsal sinus- Dorsal neck vessels- Deltoid branchesSEE DIAGRAMS
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3
Q

Artery of tarsal canal

A
  • Supplies the MAJORITY of the talar body
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4
Q

Fracture incidence

A
  • 2 % of all fractures- 6-8% of foot fractures- High complication rates (Avascular necrosis, Post-traumatic arthritis)
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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
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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
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7
Q

Hawkins I

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

Hawkins II

A
  • Displaced neck fracture- Subtalar subluxation- AVN 20 – 50 %
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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
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10
Q

Hawkins IV

A
  • Includes talonavicular subluxation- Rare variant- Complex talar neck fractures which do not fit classification can be included
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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)
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12
Q

Avascular necrosis (AVN)

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

AVN imaging - plain radiographs

A

o Sclerosis o Decreases with revascularization

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14
Q

AVN imaging - MRI

A

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

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15
Q

AVN imaging - CAT scan

A

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

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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 WBo PTB casto Can take up to 24 months to revascularize o Compliance difficulto 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 conservativelyo 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 cartilageo Most effective for lesions less than 1.5 cm