Avascular Necrosis: Pathogenesis and Clinical Findings

 • Physical Trauma (esp. to the scaphoid bone with damage to retrograde blood supply & the femoral head with damage to the circumflex vessels )

   - Severing of blood vessels that perfuse bone

 • Obstruction of Blood Flow

   - Thrombophilia (blood clots)

   - Alcoholism (fat microemboli)

   - Sickle-cell disease (sickle crisis)

   - Decompression (nitrogen bubbles)

 • Multiple causes with unclear pathogenesis

   - Glucocorticoid therapy

   - Lupus (assoc. with steroid use)

   - Radiation therapy (esp. TMJ affected)

   - Acute pancreatitis



=> Hypoxic death of bone and hematopoietic marrow cells => Avascular Necrosis => Death Of bone and marrow

 - Local bone pain

 - Joint Locking or Catching (intermittent)

 - X-Ray Findings

    • Sclerosis surrounding necrotic region

    • Collapsed bone segments

    • Subchondral hypolucency "Crescent sign"



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