Avascular (Aseptic) Necrosis of the Femoral Head (Hip)

Basics

DESCRIPTION

  • Avascular (aseptic) necrosis results from the interruption of the blood supply to bone (either traumatic or nontraumatic occlusion).
  • The femoral head is the most common site.
  • A self-limiting idiopathic avascular necrosis of the hip that occurs in children is known as Perthes disease (see “Perthes Disease” chapter).

RISK-FACTORS

GENETICS

  • Variable, depending on cause
  • Steroid-induced avascular necrosis may have an underlying genetic predisposition.

PATHOPHYSIOLOGY

  • Death and necrosis of bone with gradual return of blood supply
  • Necrotic bone gradually resorbed and replaced by new bone
  • During bone resorption, structural integrity of femoral head may be reduced, leading to collapse.

ETIOLOGY

  • Traumatic
    • Slipped capital femoral epiphysis
    • Hip fracture
    • Hip dislocation
    • Complication of casting, bracing, surgery
  • Nontraumatic
    • Steroids or chemotherapy
    • Malignancy (leukemia)
    • Idiopathic (older, after physeal closure); similar to adult avascular necrosis
    • Idiopathic (younger, before physeal closure, Perthes disease)
    • Caisson disease
    • Sickle cell disease
    • Septic arthritis
    • Gaucher disease
    • Viral infection (HIV, CMV)
    • Radiation therapy
    • Hypercoagulable states

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