Bone Diseases

Bone diseases most directly
influence the ability to walk or to move any part of
the body--hands, limbs, neck, and spine. They are
related to joint disorders--ARTHRITIS,
COLLAGEN DISEASE, DISLOCATION of
joints, and RHEUMATISM. The medical
specialty pertaining to bone disorders is
ORTHOPEDICS. Fractures are the most
common bone disorders. They can occur as the
result of an accident or be secondary to metabolic
diseases. Fractures are life-threatening to aged
people having the metabolic bone disease
OSTEOPOROSIS, in which bones become
porous and brittle. A person, mostly women,
having osteoporosis may break a hip during a fall
and possibly die from complications. Birth Defects
Congenital bone diseases constitute a wide
spectrum, ranging from the unimportant--for
instance, mild bow legs--to severe lesions, such as
spina bifida, in which the lower end of the spine
fails to develop properly and the baby is born with
paralysis and misshapen vertebrae. Congenital
diseases may have hormonal bases: for example,
fibrous DYSPLASIA, in which fibrous tissue
replaces that of some bones, often results in bone
deformity; in addition, some girls with this disease
physically mature so early that they are capable of
pregnancy and childbirth at the age of seven.
Congenital defects also may have genetic bases,
as in families who have extra fingers or toes or in
the disease osteogenesis imperfecta, in which
children have such brittle bones that many are
fractured. Disorders of growth and development
include several kinds of dwarfism and gigantism.
Bones or limbs may develop deformity as the
result of known causes, such as the infection
poliomyelitis, or unknown or variable causes, such
as curvature of the spine (SCOLIOSIS) or
CLUBFOOT. Infections Infections of bone, called
osteomyelitis, are usually caused by pus-producing
bacteria, especially Staphylococcus and
Streptococcus. Before the development of
antibiotics, children frequently contracted this
disease. Today bone infections are introduced
primarily through fractures and during surgical
operations. People infected with syphilis,
tuberculosis, leprosy, or yaws are susceptible to
bone damage. Metabolic Disorders Metabolic
abnormalities often involve defects in the storage
of minerals, particularly calcium and phosphate
ions, in the skeleton. Diseases of the kidney can
cause a metabolic imbalance of phosphate and
calcium so that weakening of the bone occurs.
Other metabolic bone diseases are osteoporosis,
gout, OSTEOARTHRITIS, and PAGET\'S
DISEASE. Nutritional Disorders Nutritional
deficiencies that result in bone damage include
RICKETS in children and osteomalacia in adults,
caused by a lack of vitamin D. In children, calcium
and phosphate are poorly distributed on bones
during development, resulting especially in
deformity of the legs and arms. In adults, bones of
the spine, pelvis, and legs become demineralized
and the bones weaken. SCURVY--caused by a
lack of vitamin C--also affects bone tissues. A
study in the late 1980s indicated that the mineral
boron is nutritionally important, as well.
Apparently, it reduces loss of the bone minerals
calcium, phosphate, and magnesium and helps to
maintain adequate blood levels of estrogen and
testosterone, which play a role in bone health.
Toxic Diseases The importance of toxic conditions
of bones to public health became evident because
of such tragedies as thalidomide-induced birth
defects and radium poisoning. The drug
THALIDOMIDE was given to pregnant women in
England and Germany for use as a sleeping pill
and to treat nausea. It caused an epidemic in
which thousands of babies were born with
deformed or missing limbs. Women employed
during the 1920s as painters of luminescent clock
dials were unwittingly exposed to radium from the
paint as they licked their brushes. Many died,
either from anemia or from bone cancer, alerting
doctors to the dangers of radioactivity and
subsequent radiation injury. Other types of toxic
bone disease include fluoride and lead poisoning
and overexposure to X rays. Tumors Bone
tumors, although not common, are not rare; benign
tumors are more common than malignant ones
(sarcomas). Metastatic tumors--those which arise
primarily in another tissue and spread by the blood
to the skeleton, where they usually grow in many
places at once--are very common in bones,
although tumors originating in bones are not. The
skeleton is second only to the lung as a site for
metastases of CANCER. More fatalities and
greater pain are associated with metastases of
bone than with any other type of cancer.
Treatments Treatments for bone diseases vary as
widely as the causes. Physical disorders often
require mechanical therapy--for instance, plaster
casts for fractures and braces and splints for
support. Drugs are used for metabolic problems,
and antibiotics for infections. Corrective surgery
benefits many people having such diseases as
scoliosis. Therapy can involve
REHABILITATION MEDICINE, by which
victims of injury, deformity, and amputation can
learn how to function as normally as possible.
Jonathan Cohen, M.D. Bibliography: Avoli, L. V.,
and Krane, S. M., eds., Metabolic Bone Disease,
2d ed. (1987); Berry, C. L., ed., Bone and Joint
Disease (1982); Greenfield, G. B., Radiology of
Bone Diseases, 4th ed. (1986); Maroteaux,
Pierre, Bone Diseases of Children, trans. by H.
Kaufmann (1979); Uhthoff, H. K., ed., Current
Concepts of Bone Fragility (1986).

Category: Science