BONE, DISORDERS OF
BONE MARROW BIOPSY
disorders (see
osteopetrosis; Paget's dis-
ease).
Bone density can be measured by
a technique known as
densitometry,
which uses low-dose X-rays.
bone, disorders of
Any of the group
of disorders that affects the bones,
including
fractures
; bone infections such
as
osteomyelitis
or a
bone abscess
;
inherited conditions such as
achondro-
plasia
and
osteogenesis imperfecta
; and
metabolic disorders such as
osteomal-
acia, osteoporosis,
and
rickets.
Tumours
and cysts (see
bone cancer
and
bone
tumour
) are another, uncommon, group
of bone disorders.
bone graft
An operation in which sev-
eral small pieces of bone are taken from
one part of the body and used to repair
or replace abnormal or missing bone
elsewhere. The bone graft eventually
dies, but it acts as a scaffold upon
which strong new bone grows.
Bone is most commonly taken from
the iliac crests (upper part of the hip-
bones), which contain a large amount
of the inner, spongy bone that is espe-
cially useful for getting grafts to “take”.
Other sources are the ribs (for curved
bone), and the ulna (in the forearm).
bone imaging
Techniques for provid-
ing pictures that show the structure or
function of bones.
X-ray
images are the
most commonly used technique for
diagnosing fractures and injuries. More
detailed information is provided by
tomography
,
CT scanning
, or
MRI
, which
can show tumours
and infections and
the effect of dis-
eased bone on the
surrounding tissues.
Radionuclide
scan-
ning
detects areas
throughout the skel-
eton in which there
is
high
bone-cell
activity. This type of
scanning
is
used
mainly to determine
whether or not can-
cer has spread to
the bones.
bone marrow The
soft fatty tissue that
is found
in
bone
cavities; it may be red or yellow. Red
bone marrow is present in all bones at
birth and is the factory for most of the
blood cells.
During the teens, red bone
marrow is gradually replaced in some
bones by less active yellow marrow. In
adults, red marrow is confined chiefly to
the spine, sternum, (breastbone), ribs,
pelvis (hip-bones), scapulae (shoulder-
blades),
clavicles
(collarbones),
and
bones of the skull.
Stem cells
within the red marrow are
stimulated to form blood cells by the
hormone erythropoietin. Yellow marrow
is composed mainly of connective tis-
sue and fat. If the body needs to
increase its rate of blood formation,
some of the yellow marrow will be
replaced by red. Sometimes marrow
fails to produce sufficient numbers of
normal blood cells, as occurs in aplastic
anaemia (see
anaemia
,
aplastic
) or when
marrow has been displaced by tumour
cells. In other cases, marrow may over-
produce certain blood cells, as occurs
in
polycythaemia
and
leukaemia.
bone marrow biopsy
A procedure to
obtain a sample of cells from the bone
marrow (aspiration biopsy) or a small core
of bone with marrow inside (trephine
biopsy). The sample is usually taken,
under local
anaesthesia
, from the ster-
num (breastbone) or iliac crests (upper
part
of
the
hip-bones).
Microscopic
examination gives information on the
development of the blood components
BONE MARROW BIOPSY
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