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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. |
| 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 Microscopic 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. |
| Clinical Correlation •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. |
| References •Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th edition. Philadelphia, W.B. Saunders, 1994, pp.1229. |
| Avascular Necrosis of Bone |
| Synopsis by: T.V. Rajan M.D. Ph.D. (T11711M54200)[89] |
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