Osteoporosis can be simply defined as an abnormal loss of bone density. The impacts of osteoporosis, however, are far from simple. Osteoporosis not only results in substantial impairments to a person’s health but can lead to a premature death. Osteoporosis can also have large adverse effects on a person’s psychological wellbeing and even affect their family and friends.

Osteoporosis is very common and becoming more prevalent. By 2007 it was estimated that 2.2 million Australians had developed osteoporosis, with a person being admitted to hospital to treat an osteoporotic fracture every five minutes.

Although genetics have a strong impact on your risk, there are still many things you can do to reduce your risk of developing osteoporosis. Before we look at how osteoporosis might be prevented, however, let’s first briefly look at what happens when osteoporosis strikes. To do this, we first need to take a quick look at the life cycle of healthy bones.

In childhood and as a young adult you literally “grew up”. This occurred up until your mid-to-late 20s as your bones became thicker and your long bones — for example, your thigh (femur) bones and leg (tibia) bones) — grew in length. At about age 25, however, your bones stopped growing in length and you consequently stopped “growing up”.

Although bones stop growing, they do not cease to be alive. In a process called remodelling, the tissue in your bones is being constantly maintained and kept healthy.

In remodelling, cells called osteoclasts dissolve small amounts of old bone. This process is called resorption. Next, cells called osteoblasts replace the bone that has been resorbed with new bone tissue. Remodelling occurs in small sections on all bones throughout life. It is a normal and healthy process.

Osteoporosis

Osteoporosis most commonly develops following pathological disturbances in the bone remodelling process. These disturbances result in significantly more old bone being dissolved by osteoclasts than new bone being deposited by osteoblasts. Consequently, the bones lose tissue and become less dense. As the bones lose their density they become weaker and more susceptible to fractures.

All bones in the body may become affected by osteoporosis. However, as most remodelling occurs in bones with a high percentage of a bone type called trabecular, osteoporosis is generally most severe in those bones. Bones with a high percentage of trabecular bone include the spine, hips and wrists, and these areas are accordingly also where most osteoporotic fractures occur.

Fortunately, a person no longer has to wait until fractures occur before they know they have developed osteoporosis. Tests are available to determine if a person has developed or is likely to develop osteoporosis. Although attempts are being made to try to accurately assess the influence bone quality might have in the development of osteoporosis, the most common tests remain bone-density tests.

The Dual-Energy X-ray Absorptiometry (DEXA or DXA) is considered to be the most reliable bone-density test at present to check for osteoporosis. This test is a quick, non-invasive and painless scan where a small amount (about 1/100th of a normal X-ray) of radiation is used to measure the density of a person’s bones, usually at the spine and hip. The results of this test indicate if a person has normal bone density, low bone density (a condition called osteopenia where about 10-15 per cent of bone density has been lost) or osteoporosis (about a 25-35 per cent bone density loss).