The sheath of new bone which is formed round a piece of dead bone in, for example, OSTEOMYELITIS.
n. a growth of new bone, formed from the *periosteum, that sometimes surrounds a mass of infected and dead bone in osteomyelitis.
n. (pl. sequestra) a portion of dead bone formed in an infected bone in chronic *osteomyelitis. It is surrounded by an envelope (involucrum) of sclerotic bone and fibrous tissue and can be seen as a dense area within the bone on X-ray. It can cause irritation and the formation of pus, which may discharge through a *sinus, and is usually surgically removed (sequestrectomy).... sequestrum
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