Biomedical Engineering Reference
In-Depth Information
It is reported that adult bone mass peaks in the second or third decade, and
middle-aged adults begin to loss bone mass at a rate of 0.7% per year [9]. In
osteoporosis, the overall density of the skeleton decreases, with thinning of the
trabeculae and loss of interconnections. The thinning and loss of interconnec-
tions lead to microfractures and eventual collapse of the vertebral body.
Osteoporotic bone fractures are responsible for considerable pain,
decreased quality of life, lost workdays, and disability. Up to 30% of patients
suffering a hip fracture will require long-term nursing home care. Elderly
patients can develop pneumonia and blood clots in the leg veins that can
travel to the lungs (pulmonary embolism) due to prolonged bed rest after
hip fracture. Osteoporosis has been linked with an increased risk of death.
Some 20% of women with a hip fracture will die in the subsequent year as
an indirect result of the fracture. Moreover, once a person has experienced a
spine fracture due to osteoporosis, he or she is at very high risk of suffering
another such fracture in the near future (next few years). About 20% of post-
menopausal women who experience a vertebral fracture will suffer a new
vertebral fracture of bone in the following year.
A bone is a dynamic, living tissue; its shape and structure continuously
evolve throughout life. It has the ability to change its structure by the
removal of old bone and replacement with newly formed bone, in a local
process called bone remodeling. Osteoporosis is the result of dysfunction
of bone remodeling, in that the rate of bone loss is greater than that of bone
gain, which gives rise to a porous bone that breaks easily.
Osteoporosis is quite common in elderly people. It is estimated that 25%
of women older than 65 may have sustained a crush fracture as a result of
osteoporosis [8]. The high prevalence and morbidity associated with osteo-
porosis has induced the medical community to develop means of prevention
of the disease and to search for means of reversing bone loss. Prevention and
reversal of bone loss demand a thorough understanding of the remodeling
process in bone at the cellular level, including hormonal action. Treatment
is exemplified by PTH (see Section 1.6) and mechanical and electromagnetic
stimulation.
The goal of treatment of osteoporosis is the prevention of bone fracture by
reducing bone loss or, preferably, by increasing bone density and strength.
Although early detection and timely treatment of osteoporosis can substan-
tially decrease the risk of future fractures, none of the available treatments
for osteoporosis are complete cures. In other words, it is difficult to rebuild
completely a bone that has been weakened by osteoporosis. Prevention of
osteoporosis is therefore just as important as treatment. Osteoporosis treat-
ment and prevention measures entail lifestyle changes, including quitting
cigarette smoking, curtailing excessive alcohol intake, exercising regularly,
consuming a balanced diet with adequate calcium and vitamin D, and
improving bone remodeling processes. In particular, it is interesting to study
the treatment of osteoporosis by reducing bone loss and increasing bone
density and strength through improving bone remodeling processes.
