The Skeletal System
is defined as a decrease in the absolute amount of bone that can lead to
fractures following minimal trauma. The bone that remains is histologically
and biochemically normal, but there is not enough of it to maintain normal
skeletal integrity and sufficient mechanical support. Osteoporosis develops
when the net rate of bone resorption exceeds the rate of bone formation,
resulting in a decrease in bone mass without a defect in bone mineralisation.
The end result is brittle, light but firm bones.
It is by far the commonest
form of metabolic bone disease and a major public health problem. Bone mass is
determined by genetic and environmental factors and reaches a peak around the
age of 35 and remains largely unchanged for next 10 years. After that there is
net bone loss of about 0.3-0.5% per year. Age-related bone loss is greatly
accelerated in women after the menopause due to loss of oestrogen production.
It has been estimated that the rate of bone loss after the menopause can be as
high as 3-5% per year. Decreased physical activity in older persons may also
be very important because preservation of bone mass depends on skeletal stress
through muscle contraction and weight bearing. Radius fractures, femoral neck
fractures and vertebral fractures are all related to osteoporosis, although
not everyone with low bone mass will experience them.
risk factors for
osteoporosis have been identified:
stature and thin physical constitution (obesity is associated with higher bone
mass because of physical stress on bones)
calcium and phosphate intake
of aluminium antacids (they bind calcium in the gut preventing its absorption)
protein intake in form of red meat
can be classified into primary (95%
of all cases) and secondary (5% of
is further divided into the following two types although there is a
significant overlap between them:
Type I (postmenopausal) osteoporosis that starts to develop after the age of 50 and is six times more common in women but can occur in men after castration or with low levels of testosterone. This type is associated with fractures such as distal radius (so called Colles?fracture) and vertebral crush fractures.
II (involutional or senile) osteoporosis is associated with ageing process when there is progressive but gradual
loss of osteoblastic activity in the bone. This type occurs in individuals
older than 60 years and it is twice as common in women as in men (in older
women type I and II frequently coexist). The most common type of fractures are
those of the femoral neck (hip), wedge vertebrae, proximal humerus, proximal
tibia and pelvis.
Secondary osteoporosis is associated with certain
endocrine disorders such as glucocorticoid excess in Cushing’s syndrome (glucocorticoids
stimulate catabolism of proteins in the bone, reduce activity of osteoblasts
and promote activity of osteoclasts), hyperparathyroidism (PTH mobilises
calcium from bones), long term treatment with heparin (anticoagulant) or
barbiturates (in combined antiepileptic preparations), prolonged
immobilisation, chronic liver and kidney failure (due to impaired activation
of vitamin D in these organs) and various malabsorption syndromes (impaired
absorption of calcium and vitamin D).
Clinical features: < BACK TO TOP >
with uncomplicated osteoporosis may remain asymptomatic or may have aching
pain in the bones, particularly the back.
fractures develop with minimal or no trauma, usually in weight-bearing
vertebrae (Th-8 and below).
pain is acute, usually does not radiate, is aggravated by weight-bearing, may
be associated with local tenderness, and generally subsides in a few days or
compression fractures may cause marked height reduction and thoracic kyphosis
(hunchback) with exaggerated cervical lordosis and chronic, dull, aching pain
(because of excessive stress on the back muscles and ligaments caused by
abnormal body posture), particularly prominent in the lower thoracic and
Fractures at other sites (e.g., hip or distal radius) usually result from an accidental fall.
Diagnosis: < BACK TO TOP >
biochemical measurements are usually normal but the alkaline phosphatase
(produced by osteoblasts) may be raised following a recent fracture,
reflecting repair process in progress.
of parathyroid hormone (PTH) may be elevated in primary hyperparathyroidism
(due to benign autonomously functioning tumour of the parathyroid gland) or
secondary (hypocalcaemia caused by decreased activation of vitamin D,
impaired absorption of calcium and vitamin D) hyperparathyroidism.
shows decrease in bone density as well as the characteristic wedge and crush
fractures in the spine but it has been calculated that at least 40% of bone
mineral must be lost before the changes are detectable on plain X-ray films.
gold standard for diagnosis of osteoporosis is dual energy X-ray absorption
scan (DEXA scan). The test is performed by passing low energy X-rays through
a bone (e.g. spine, hip or wrist). The test takes about ten minutes and is
associated with very limited radiation exposure (less than during one plain
results are expressed in units referred to as standard deviations (SD). These SD
units tell how much a result differs (or deviate) from what is considered
normal. If one is 2.5 SD units below normal (-2.5), this is considered to be
Heel ultrasound is an interesting new technology for testing bone density. The test usually involves immersing a foot in a bath of warm water, allowing high frequency sound waves to pass through the heel. The test measures the density and quality of the bone in the heel. It has not yet become a standard testing procedure but since the equipment is portable it may nicely supplement DEXA as a screening procedure.
Management < BACK TO TOP >
pharmaceutical measures such as regular physical exercise in any form,
adequate calcium intake (more than 1g per day), avoidance of smoking and
alcohol are intended to minimise bone loss.
small daily supplement of vitamin D [Rocaltrol, Caltrate or similar] (400 IU)
replacement therapy (HRT) with oestrogens, with or without progestogen
component, should be considered in postmenopausal women with low bone mass
especially with family history of bone fractures. However, HRT is not a
substitute for healthy life style and may increase risk for endometrial and
[Fosamax] and etidronate [Didronel, Didrocal] inhibit osteoclast-mediated
bone resorption and may be an alternative for postmenopausal women in who
they can significantly decrease the risk of fracture. These drugs must be
taken with a lot of water due to their ability to cause irritation and damage
of the oesophagus if the tablet lodges there. Because of this and possible
gastric irritation this treatment is usually reserved for individuals who
already developed osteoporosis-related bone fracture or are in great risk to
have it (e.g., strong family history, low bone density).
Treatment of fractures often proves difficult because brittle bones mend very slowly. Prolonged hospitalisation and immobility increase the risk for deep leg vein thrombosis, pulmonary embolism and/or pneumonia, which are very serious, sometimes life threatening complications.
Prognosis < BACK TO TOP >
Dr Zoran Pletikosa)
12 August 20096December 2005
speaker Mr NgThian Watt the Principal Trainer from
Napoleon Hill Associates MalaysiaDetails