Avascular necrosis

Epidemiology

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Etiology

Though often idiopathic, several traumatic and atraumatic factors may contribute to the development of osteonecrosis.

• Atraumatic factors
  • Glucocorticoid use (35–40% of cases)
  • Alcohol use disorder (20–40% of cases)
  • Legg-Calvé-Perthes
  • Hemoglobinopathies (e.g., sickle cell disease)
  • Autoimmune diseases (e.g., SLE, antiphospholipid syndrome)
  • Pancreatitis
  • Infection
  • Gaucher disease
  • Decompression sickness
• Traumatic factors
  • Femoral neck fractures, particularly with dislocation
  • Femoral head fracture
  • Slipped capital femoral epiphysis (SCFE)

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Pathophysiology

Ischemic death of bone and marrow in the femoral head due to disruption of the blood supply, primarily from the medial circumflex femoral artery.

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Clinical features

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Diagnostics

Imaging

• X-ray: best initial test
  • Findings
    • Cystic and sclerotic changes in the femoral head
    • Subchondral collapse
    • Flattening of the femoral head
• MRI: confirmatory test
  • Findings
    • Visualization of the interface between necrotic and viable bone

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Treatment

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