Bones affected by osteoporosis are lighter and less dense than normal. They are also more likely to break, even as a result of a minor bump or fall, or even without an injury. Osteoporosis means porous bones.
Osteoporosis is around four times more common in women than men, and most common in women who have been through the menopause.
As well as bones such as the wrist or hip breaking more easily than usual, osteoporosis can result in small fractures of the bones in the spine. This can cause a curved back and a loss of height.
The inside of a bone consists of a strong mesh made of protein and minerals (particularly calcium). This mesh is living tissue that is constantly being renewed by a process called bone turnover. Old, worn out bone is broken down and absorbed by the body while, at the same time, new bone tissue is created from fresh protein and minerals. In children and young people, more new bone is created than is broken down. This makes bones both bigger and denser.
The bones are at their strongest when the peak bone mass is reached, and this usually occurs in a persons mid-twenties. Peak bone mass is then maintained for about ten years, with roughly equal amounts of bone creation and breakdown. After the age of about 35, bone loss begins to overtake creation. This is a natural aging process but with osteoporosis, the process happens much more quickly, leading to premature bone weakness.