It’s crunch time – how are your bones?

Dr Roderick Brooks
Did you know the body had over 200 bones? The three tiniest are in the middle ear, where they conduct vibrations to the inner ear, so we can hear. The largest are the femora or thigh bones – the big bones of the lower limb have to be strong for weight-bearing, walking and running.

And what do bones really look like? The surface of healthy bones has a creamy-white colour, and bone is wrapped in a vital membrane, the periosteum, which helps carry nutrients to the bone. But on the inside, bones are red, like a dense honeycomb structure of tiny walls and cavities, coursing with blood. If a bone breaks, it bleeds.

subhead: Lifecycle of bones

Children’s bones are softer and more flexible, hence their tendency to kink rather than snap – the “greenstick fracture”. Even adult bones have some flex in them, which helps them absorb the shocks of weight-bearing.

Our bones attain maximum resilience early in adulthood, typically around 25 to 30. By age 40, bones are starting to lose their strength. The rate of bone loss will accelerate in females after the menopause, as the protective effect of female hormones is diminished. HRT (hormone replacement therapy) may be an option to help postpone the decline in bone strength; however this needs to be considered in the context of your general health, as there could be unwanted effects.

subhead: What is “Osteo”?

Osteoporosis means softening or fragility of bones – not to be confused with osteoarthritis, which refers to joint degeneration. The diagnosis of osteoporosis may be apparent, for example in someone where fractures are occurring with quite minor injuries. It can be seen on X-rays, or diagnosed more precisely by Bone Densitometry, available at Radiology or Nuclear Medicine facilities.

Treatments for osteoporotic fractures have improved greatly in recent decades. In particular modern surgical techniques and devices can stabilize breaks better and allow people to function in relative comfort while healing occurs.

subhead: Prevention is better than cure

The best way to avoid the problems of osteoporosis later in life is to live healthily in our early lives. The more strength we can build into our skeletons before they reach their “peak bone mass “ – our mid-twenties – the better placed we will be for the later stages of adulthood when bone loss is occurring.

So how can we build healthy bones? Think of bones as a living and responsive body organ – they need weight-bearing stresses to retain and build their calcium content. Put an astronaut in space, and after a while the zero-gravity environment will tend to cause osteoporosis. Put a healthy person to bed for six weeks and the same thing will happen. Even one limb can become osteoporotic, such as when protecting an injured limb by using crutches – bone strength will be gradually restored once weight-bearing is re-introduced. No wonder the recovering limb feels funny or weak for a time.

So plenty of weight-bearing exercise early in life will help build bone mass. Genetic factors also play a role. And bone mass will tend to be higher in males than females. Adequate calcium and Vitamin D intake is essential, particularly when bones are growing in children and adolescents – milk and yoghurt are excellent sources, as are green leafy vegetables, and salmon and similar fish.

And sunlight is necessary to form Vitamin D in the skin – 10 minutes in the middle of the day in summer will suffice. More at risk are people who live indoors, such as in institutions, and who cover their skins for cultural reasons.

Is it possible to over-exercise? Teenagers’ bones are still gathering strength, and might not tolerate the repetitive stresses which a 30–year-old could support. For example an over-enthusiastic running program could end up causing a stress fracture. And in young women, if exercise results in excessive weight loss, the periods might stop, causing a loss of oestrogen support at a critical time for bone formation. So moderation is the key!

subhead: Over 50?

The best form of exercise for the over fifties is walking – it’s free and accessible. Between 30 and 40 minutes, three or four times per week is a reasonable amount.

Whom should I ask about my bones?

Your GP knows a lot about bone health and disorders, and can advise you on prevention and treatments suited to your particular circumstances. A specialist referral to an Endocrinologist might be considered if you have a relatively severe problem affecting your bones. There are medications which can help.

Orthopaedic Surgeons treat bone problems also, particularly in the context of injuries or breaks, bone pains and joint diseases such as arthritis, while Rheumatologists specialize in the medical treatment of arthritic and inflammatory disorders.

_____________________________________________________________________Dr Roderick Brooks is an Orthopaedic Surgeon in Wahroonga operating at the San Hospital and specialising in hip and knee surgery.

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