What
is osteoporosis?
In
osteoporosis (which means 'porous bones') bones become weak and
fragile which means that even a minor bump or accident can result in
a broken bone known as a minimal trauma fracture. These can result in
chronic pain, disability, loss of independence and premature death.
Brittle bones usually result from a decrease in bone mineral density
(BMD) and changes in bone quality (See Figure 1). Decreased bone
density occurs when bones lose minerals including calcium faster than
the body is able to replace them.
Figure
1: Difference between healthy bone and osteoporosis. Image sourced
from AIHW (http://www.aihw.gov.au/osteoporosis/what-is/)
Osteopenia
is a related condition where the mineral density is lower than normal
but not enough to be classified as osteoporosis.
The
'fracture cascade'
The
risk of future fractures increases with each new fracture, known as
the 'cascade effect', with women who have a spinal fracture 4x more
likely to have another fracture within a year. This number increases
the more fractures an individual experiences, with an 11x greater
risk of fracture in people who have already experienced 3 or more
compared to someone who hasn't had one.
Who
is at risk?
Older
people and post-menopausal women have a greater risk of developing
osteoporosis or osteopenia. It is a common disease in Australia with
almost 1 in 10 Australians over the age of 50 have either
osteoporosis or osteopenia, with women over the age of 50 years 4x as
likely to be affected by these conditions than men of the same age.
This is because of the rapid decline in oestrogen levels during
menopause which results in an increased rate of loss of bone calcium
and other minerals. This results in approximately 2% bone loss per
year occurring for several years post menopause. The rate of
hospitalisation for minimal trauma fracture is 2.6x higher for women
over 50 compared to men.
Risk
factors for osteoporosis
There
are a number of risk factors associated with the development of
osteoporosis including:
- Increase in age
- Being female
- Having an early menopause or being postmenopausal due to the rapid decline in oestrogen levels
- Family history of osteoporosis
- Reduced levels of oestrogen
- Low calcium intake
- Low levels of vitamin D (which your body needs to absorb calcium)
- Low body weight or small frame
- Smoking
- Lack of physical activity
- Excessive alcohol consumption
- Medical history including: malabsorption disorders (e.g. coeliac disease), some hormonal disorders (e.g. thyroxine excess) or long-term use of certain medications (e.g. corticosteroids)
Symptoms
and resulting issues
Osteoporosis
usually has no signs or symptoms until a fracture occurs, hence why
it is known as a 'silent disease'. Osteoporosis (and the associated
fractures) can result in:
- Increased risk of fractures
- Loss of height
- Severe back pain
- Change of posture
- Muscle weakness
- Spinal bone deformity
- Impaired ability to walk
- Chronic pain
- Loss of independence
- Premature death
Diagnosis
of osteoporosis
Osteoporosis
is often referred to as a silent disease as it can progress
undetected for many years until a fracture occurs. It is diagnosed
using a bone mineral density test (also known as a 'dual energy X-ray
absorptiometry (DXA) scan') to measure the bone mineral density in
the hips and spine. The results of the scan will be compared to the
average BMD of healthy adults and expressed the as a T-score. The
range of T-scores will determine whether the individual's bone
density is normal or an indication of osteopenia or osteoporosis (See
Table 1).
Table
1: How T scores relate to bone density health
Condition
|
T
score
|
Normal
|
1
to -1
|
Osteopenia
|
-1
to -2.5
|
Osteoporosis
|
-2.5
or lower
|
Prevention
and management of osteoporosis
The
best prevention methods depend on your bone density and T-score
results. If the test shows normal bone density recommendations for
maintaining good bone health include exercise and adequate intake of
calcium and vitamin D. If the test shows osteopenia further lifestyle
changes may be required as well as a follow up bone density scan in
1-2 years to monitor your bone health. If the results show
osteoporosis it means you are at risk of fracture and important
lifestyle changes and fall prevention measures need to be taken.
You'll also likely start treatment to prevent further bone loss and
fractures and require a follow up test in a year's time. It is
essential that any osteoporotic fractures are identified and treated
as quickly as possible in order to stop the fracture cascade.
Lifestyle
changes
Additional
modifications to day to day behaviour can prevent or slow down the
development of osteoporosis, or lessen the effects of the disease.
These include:
- Increasing calcium intake through diet or supplements
- Increase vitamin D levels with sunlight exposure or supplements
- Partaking in regular weight-bearing exercise
- Stopping smoking
- Decreasing alcohol intake
- Possible changes in your normal medications
- Adjusting behaviour to avoid fractures wherever possible
Medications
Bone
tissue is constantly broken down (by osteoclasts) and renewed (by
osteoblasts) in a carefully balanced cycle. Osteoporosis unbalances
this cycle. Medications for managing osteoporosis inactivates
osteoclasts to stop bone tissue break down, but allows osteoblasts to
continue forming new bone tissue. This results in a gradual increase
in bone tissue density over time.
Useful
resources
AIHW
Osteoporosis
Australia
Artritis
WA
Osteoporosis
Medications
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