Osteonecrosis Flashcards

1
Q

What is it?

A

Ischaemic bone necrosis of all types

Ischaemia- bone marrow cells die within 12 hours followed by bone cells (osteoblasts etc.) in 12-24hrs

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2
Q

What are the different types of osteonecrosis?

A

Osteonecrosis of long bones

  • bone infarction
  • involves trabecular bone and bone marrow in medulla
  • cortex has different blood supply

Osteonecrosis in the epiphysis

  • called avascular necrosis
  • can involve cortex also
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3
Q

What are the causes?

A

Interrupted arterial supply e.g. fractures

Interrupted venous drainage and retrograde arterial stoppage e.g. thrombosis

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4
Q

What are the risk factors?

A
Fracture e.g. NOF/Scaphoid
Idiopathic e.g. Perthe's disease
Bone marrow infiltration e.g. malignancy
Alcohol abuse
Cushings/exogenous steroid/chemo
Infection e.g.SA
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5
Q

Which bones are commonly affected?

A

Head of femur
Proximal scaphoid
Lunate
Body of talus

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6
Q

What are the symptoms?

A
Well advanced at presentation
Pain
Stiffness
Swelling
In a joint but can be over bone
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7
Q

What are the investigations?

A

XR

  • Sclerosis
  • Flattening
  • Subchondral radiolucent lines- crescent sign
  • Collapse of cortex

Can take 6 months for changes to show

MRI can show earlier

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8
Q

What is the treatment?

A

Treat underlying cause
Prevent complications- stop fracture by weight relief or splint
Surgery where needed

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