immobilized in a plaster castto allow
reattachment. Loosebone or cartilage
fragments in the knee are removed dur-
ing arthroscopy. Disruption to the
smoothness of the joint surface increas-
es the risk of osteoarthritis.
osteochondritis juvenilisInflamma-
tion of an epiphysis(growing end of
bone) in children and adolescents, caus-
ing pain, tenderness, and restricted
movement if the epiphysis forms part of
a joint. The inflammation leads to soft-
ening of the bone, which may result in
deformity. The condition may be due to
disruption of the bone’s blood supply.
There are several types: Perthes’ disease;
Scheuermann’s disease, which affects
several adjoining vertebrae; and other
types that affect certain bones in the
foot and wrist.
The affected bone may be immobi-
lized in an orthopaedic braceor plaster
cast. In Perthes’ disease, surgery may be
required to prevent more deformity. The
bone usually regenerates within 3 years
and rehardens, but deformity may be
permanent and increases the risk of
osteoarthritisin later life.
osteochondromaA noncancerous bone
tumour, which is formed from a stalk
of bone capped with cartilage, and
appears as a hard round swelling near a
joint. An osteochondroma develops in
late childhood and early adolescence,
usually from the side of a long bone
near the knee or shoulder. The tumour
causes problems only if it interferes
with movement of tendons or the sur-
rounding joint, in which case it may be
removed surgically. Large osteochondro-
mas can interfere with skeletal growth,
causing deformity.
osteochondrosisSee osteochondritis
juvenilis.
osteodystrophyAny generalized bone
defect due to metabolic disorders. Types
of osteodystrophy include rickets; osteo-
malacia; osteoporosisdue to Cushing’s
syndrome or excessive intake of cortico-
steroid drugs; and bone cysts and bone
mass reduction associated with chronic
kidney failureor hyperparathyroidism. In
adults, an osteodystrophy is usually
reversible if the underlying cause is
treated before bone deformity occurs.osteogenesis imperfectaA congenital
condition characterized by abnormally
brittle bonesthat are unusually suscep-
tible to fractures. The condition is caused
by an inherited defect in the connective
tissuethat forms the basic material of
bone. Severely affected infants are born
with multiple fractures and a soft skull
and do not usually survive. Others have
many fractures during infancy and child-
hood, often as a result of normal
handling and activities, and it may be
difficult to distinguish the condition from
child abuse. A common sign of the con-
dition is that the whites of the eyes are
abnormally thin, making them appear
blue. Sufferers may also be deaf due to
otosclerosis. Very mild cases may not be
detected until adolescence or later.
There is no specific treatment. Frac-
tures are immobilized and usually heal
quickly, but they may cause shortening
and deformity of the limbs, resulting in
abnormal, stunted growth. Skull frac-
tures may cause brain damage or death.
Parents may have genetic counsellingto
estimate the risk in future children.
Severe cases can be diagnosed prena-
tally by ultrasound scanning.
osteogenic sarcomasee osteosarcoma.
osteoid osteomaA bonedisorder in
which a tiny abnormal area of bone, usu-
ally in a long bone, causes deep pain,
which is typically worse at night. The
condition is cured by removing the area
of bone. (See alsoosteoma.)
osteomaA hard, noncancerous, usually
small tumour that may occur on any
bone. Surgical removal may be neces-
sary if an osteoma causes symptoms by
pressing on surrounding structures.
osteomalaciaSoftening, weakening, and
demineralization of bonesin adults due
to vitamin Ddeficiency. Osteomalacia is
rare in developed countries; it most
commonly affects housebound, elderly,
and dark-skinned people who live in
countries that have less sunlight than
their country of origin.
Healthy bone production requires cal-
cium and phosphorus, which cannot be
absorbed from the diet without suffi-
cient vitamin D (found in certain foods
and manufactured by the skin in sun-
light). Causes of osteomalacia include aOSTEOCHONDRITIS JUVENILIS OSTEOMALACIAO