What is osteoporosis?

Osteoporosis is a condition in which bones lose their strength and are more likely to break, usually following a minor bump or fall.

In medical terms, osteoporosis is a bone density of 2.5 SD (standard deviation) below average, or less, as measured on a bone density (DXA) scan.

Osteoporosis doesn't show any outward symptoms and the first sign of osteoporosis is often a broken bone. The bones most commonly fractured as a result of osteoporosis are the wrist, hip and spine.

Osteoporosis itself is does not cause pain - it is the broken bones caused by osteoporosis can be painful, and sometimes lead to long-term difficulties. Spinal compression fractures can cause a change in body shape and ongoing, chronic back pain. Hip fractures can result in loss of independence or reduced health and wellbeing. These long-term difficulties can have a big impact on quality of life for those affected.

more about the consequences of osteoporosis

What causes osteoporosis?

As we go about our daily lives, the older, worn-out bone tissue in our bones is being broken down by specialist cells called osteoclasts and rebuilt by bone-building cells called osteoblasts. This process of renewal is called bone-remodelling.

In childhood, osteoblasts work faster, enabling the skeleton to increase in size, density and strength. Bones stop growing in length between the ages of 16 and 18 years but the total amount of bone tissue we have continues to increase slowly until our late twenties.

In younger adults, up until about the age of 35 years, there is usually a balance between the amount of bone that is removed by these specialist cells and the amount of bone that is laid down, meaning the total amount of bone tissue we have stays the same.

After the age of about 35 years, the body starts to remove more bone than it replaces. As a result, the total amount of bone tissue starts to decrease. This is often described as ‘bone loss’ or ‘bone thinning’. Our bones won’t look any different from the outside but inside, the cortical ‘shell’ thins and the struts that make up the inner structure become thinner and sometimes break down.

Bone thinning

Bone thinning is much more significant as we move into later life, which explains why osteoporosis and broken bones become more common in old age.

Not everyone will experience broken bones due to osteoporosis. There are many other risk factors that contribute towards low bone strength, besides just age. However, the older we get, the more likely osteoporosis and broken bones become.

More about bone strength

Who is affected by osteoporosis?

Generally speaking, post-menopausal women are most prone to developing osteoporosis and fractures, although it is possible for men, younger adults and rarely even children to develop the condition too.

  • Women
  • Men
  • Younger men and women