Perthes Disease



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


  • Incidence varies depending on the region: 0 to 15 per 100,000 children <15 years of age
  • In United States and Canada, about 5 per 100,000
  • Rare in persons of African descent
  • Most frequent in children 4 to 8 years old
  • 3 to 5 times more common in boys than girls
  • 10–15% develop bilateral disease in asynchronous fashion.
  • Associated factors: delayed bone age, hyperactivity, exposure to smoking, genitourinary anomalies (hypospadias, undescended testis, and inguinal hernia)


  • A partial or complete disruption of femoral head blood supply produces a partial or total femoral head osteonecrosis.
  • Greater the head involvement, worse 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 head goes through four stages of healing over 3 to 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 to 2 years.
    • 3. Stage of reossification: New bone begins to fill the epiphysis; longest stage, lasting up to 3 years
    • 4. Healed: Head is completely reossified. Not all heads heal back in round shape, and deformed 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)
    • Smoke exposure

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