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| Avascular Necrosis of Bone |
| Etiology |
•Any cause of
interruption of blood supply can result in
bone necrosis. •Fractures, thrombosis and embolism, injury of vessels due to
vasculitis, and hypertension are all associated with bone
infarcts. •Corticosteroid administration is frequently associated with
bone necrosis. |
| Pathogenesis |
•Any interruption of blood supply results
in aseptic necrosis of bone. •The role of steroids in the genesis of avascular necrosis is
not understood. |
| Epidemiology |
•Fairly common. |
| Clinical |
•Bone necrosis causes chronic pain, usually on exercise,
subsequently at rest. •Subchondral infarcts, which result in necrosis of overlying
cartilage, can result in severe osteoarthritis. |
| General Gross Description |
•Necrosis is typically sharply demarcated. •It may involve only the cancellous bone and marrow; because
of blood supply from the periosteum, cortical bone is usually
not affected. •The infarct is typically triangular or wedge shaped. |
| General Micro Description |
•As with necrosis due to any cause, avascular necrosis of bone
is recognized by the absence of cells in lacunae. •Necrosis of the marrow space resembles fat necrosis elsewhere
and is typified by the presence of bluish, acellular material. •The blue color is due to the formation of calcium soaps,
derived from fatty acids released by breakdown of fat in
adipocytes. |
| Reference |
•Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th edition. Philadelphia, W.B. Saunders, 1994, pp.1229.
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