An island of nonvital bone that is separated from native healthy bone.
A segment of dead bone; the result of an abscess from a bacterial infection in a bone and bone marrow.
A fragment of bone that separates as the result of infection or injury.
A piece of dead bone which is separated from whole bone.
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).
A fragment of dead bone cast off from the living bone in the process of necrosis. A sequestrum often remains in contact with, and partly enveloped by, newly formed bone, so that a sinus is produced; a constant discharge goes on until the dead bone is removed.
A fragment of a necrosed bone that has become separated from the surrounding tissue. It is designated primary if the piece is entirely detached, secondary if it is still loosely attached, and tertiary if it is partially detached but still remaining in place.
A deceased fragment of bone that has detached from a typically healthy bone, typically due to infection.