the SKeLetaL SyStem 99genetic diseases, infections, and cancer
all may affect the skeleton
Some skeletal disorders are inherited, and a few cause life-
long difficulties. An example is osteogenesis imperfecta or OI
(Figure 5.14). In this incurable disease, the collagen in bone
tissue is defective, so the bones are extremely brittle and
break easily. Children with OI must have surgeries to set
the fractures and often have stunted growth.
Bones (and bone marrow) can become infected when a
bacterial infection elsewhere spreads (via the blood stream)
or when the microbe enters an open wound. Antibiotics
usually can cure the problem, although severe cases may
require surgery to clean out the affected bone tissue.
The bone cancer called osteosarcoma strikes people young
and old. It often develops in a long bone in a limb, or in a
joint such as the hip or knee. The most common treat-
ment of a primary bone cancer is amputation of the limb
involved. Like many other types of cancer, bone cancer
often is curable if caught early. Unfortunately, many bone
cancer cases involve cancer that has spread from another
site in the body. In the series of bone scans shown below,
red “hot spots” show the progression (left to right) of a
patient’s bone cancer.heating pad. The warmth speeds healing by increasing
blood circulation to the injured tissue.
A blow can dislocate a joint—that is, the two bones will
no longer be in contact. During collision sports such as
football, a blow to a knee often tears a ligament. If the torn
part is not reattached within ten days, phagocytic cells in
the knee joint’s synovial fluid will attack and destroy the
damaged tissue.
bones break in various ways
Most bone breaks can be classed as either a simple or closed
fracture, a complete fracture, or a compound fracture. As
you can probably tell from the drawings in Figure 5.13,
a simple fracture is the least serious injury because the
bone ends don’t do much damage to the surrounding soft
tissue. A complete fracture, in which the bone separates
into two pieces and soft tissue is damaged, is more serious.
Worse is a compound fracture, in part because broken
ends or shards of bone puncture the skin, creating an open
wound and the chance of infection. A surgeon may have
difficulty reattaching all the pieces of a bone that has been
shattered in this way.
When a bone breaks into pieces, the pieces must quickly
be reset into their normal alignment. Otherwise it’s unlikely
that the bone will heal properly. Its functioning may be
impaired for the rest of a person’s life. In addition to the
pins and casts that may be used to hold healing bones in
place, the injured area may be stimulated with electricity,
which speeds healing.
Joint and bone injuries tend to heal faster when we’re
younger. Changes that come with aging and bad habits
such as smoking cigarettes slow the body’s ability to
repair itself.
Figure 5.14 Osteogenesis imperfecta is a genetic bone disorder.
Left: An X-ray of an arm bone deformed by OI. Right: Tiffany, who
was born with OI.© Paul Sponseller, MD/Johns Hopkins Medical Center© Courtesy of the Family of Tiffany ManningFigure 5.13 Bone fractures range from simple to much more
serious compound fractures. (© Cengage Learning)
A Simple B Complete c Compound
Scott Camazine/Science SourceCopyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).