Perthes Disease

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Childhood femoral head osteonecrosis of unknown etiology, which can weaken the femoral head and produce a permanent femoral head deformity in some patients, predisposing them to early arthritis


  • Prevalence varies depending on the region: 0–15 per 100,000 children <15 years of age.
  • In the United States and Canada, about 5 per 100,000
  • Rare in African Americans
  • Most frequent in children 4–8 years old
  • 3–5 times more common in boys than girls
  • 10–15% develop bilateral disease in asynchronous fashion.


  • A partial or complete disruption of blood supply to the femoral head produces a partial or total femoral head osteonecrosis.
    • The greater the femoral head involvement, the worse the prognosis.
    • Bone necrosis and subsequent resorption of necrotic bone weaken the femoral head.
    • Weight bearing worsens the femoral head deformity.
  • Chronic hip joint synovitis also develops producing pain and restriction of motion.
  • Necrotic femoral head goes through 4 stages of healing over 3–5 years:
    • 1. Stage of avascular necrosis
      • Smaller femoral head epiphysis with increased radiodensity
    • 2. Stage of fragmentation
      • Necrotic epiphysis shows fragmentation.
      • Necrotic bone is resorbed, weakening the head.
      • Most deformity occurs during this stage, which lasts 1–2 years.
    • 3. Stage of reossification
      • New bone begins to fill the epiphysis.
      • Longest stage, lasting up to 3 years
    • 4. Healed
      • Femoral head is completely reossified.
      • Not all heal back in round shape, and deformed femoral heads are at risk for developing arthritis later.


  • Unknown
  • Unlikely genetic transmission, as <5% have family history
  • Many theories:
    • Multifactorial (genetic predisposition with environmental trigger)
    • Hyperactivity and subclinical trauma
    • Type II collagenopathy
    • Thrombophilia (factor V Leiden)
    • Tobacco smoke exposure

Commonly Associated Conditions

  • Delayed bone age
  • Hyperactivity
  • Genitourinary anomalies (hypospadias, undescended testis, and inguinal hernia)

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