Bone of contention

Most of us are familiar with the term "osteoporosis" - a loss of bone mass and deterioration in the structure of bone tissue, with an increase in risk of bone fracture.
It is recognised as a serious public health problem: there's the increase in our ageing population, the rise in mortality and consequently the economic cost associated with fractures.
Our springy bones
Bone is, in essence, an elastic structure. our body constantly absorbs old bone cells and lays down new bone.
The trigger that alerts our bodies to lay down new bone is stress or loading such as weight-bearing exercise. When we exercise, our bones become stronger and heavier as a consequence of the increase in stress, providing we don't stress our bones too quickly.
So who is at risk?
Believe it or not - astronauts. however, there are certain people on the ground also at risk.
Osteoporosis is more common in female Caucasians, particularly if there is family history of the condition. The risk increases after menopause as estrogen has an effect on bone strength.
Other risk factors include smoking, poor nutrition, following a prolonged period of bed rest, low body weight, or as a side effect of prolonged use of medications such as steroids.
Another big risk factor is age. We reach our peak bone mass at 25 and from there on it is all downhill.
From our late 20s and early 30s, we lose bone mass. That is why it is so important for children and adolescents to eat well and exercise for bone health.
From the age of 25, we don't get a second chance.
How will I know?
The first symptom of osteoporosis is a fracture. these fractures commonly involve the wrist, hip, rib or thoracic spine and can often occur with mild trauma or even with simple everyday tasks.
Fractures in the spine cause some collapse of the vertebral body and will lead to changes in posture and height.
Fractures are often tiny and may not be visible on an X-ray, but can still cause significant pain.
By the time bone thinning is evident through X-rays, about 30 per cent of bone mass has been lost and osteoporosis is more advanced.
The most reliable test of bone density is a DXA scan which gives an accurate measure of bone mass.

What can I do?
One of the simplest ways to help prevent and manage problems associated with low-bone density is regular exercise.
Weight-bearing exercise helps maintain bone strength and density, and it also helps in reducing the risk of falls. A daily walk or a regular light weight programme is a good way to get this exercise.
Exercises to help improve balance are also important to reduce the risk of fracture associated with falls.
A diet rich in calcium is also essential to good bone health. Good sources of calcium include dairy products, green vegetables, meat and fish, nuts and seeds.
Good eating and exercise habits early on help determine our health later in life.
Michelle Sintmaartensdyk is a physiotherapist. She has postgraduate qualifications in manipulative physiotherapy and sports medicine. She is also a registered physiotherapy acupuncturist.