By Meghan Betts
What is osteoporosis?
In osteoporosis (which means ‘porous bones’) bones become weak and fragile which means that even a minor bump or accident can result in a broken bone known as a minimal trauma fracture. These can result in chronic pain, disability, loss of independence and premature death. Brittle bones usually result from a decrease in bone mineral density (BMD) and changes in bone quality (See Figure 1). Decreased bone density occurs when bones lose minerals including calcium faster than the body is able to replace them.
Figure 1: Difference between healthy bone and osteoporosis. Image sourced from AIHW (http://www.aihw.gov.au/osteoporosis/what-is/)
Osteopenia is a related condition where the mineral density is lower than normal but not enough to be classified as osteoporosis.
The ‘fracture cascade’
The risk of future fractures increases with each new fracture, known as the ‘cascade effect’, with women who have a spinal fracture 4x more likely to have another fracture within a year. This number increases the more fractures an individual experiences, with an 11x greater risk of fracture in people who have already experienced 3 or more compared to someone who hasn’t had one.
Who is at risk?
Older people and post-menopausal women have a greater risk of developing osteoporosis or osteopenia. It is a common disease in Australia with almost 1 in 10 Australians over the age of 50 have either osteoporosis or osteopenia, with women over the age of 50 years 4x as likely to be affected by these conditions than men of the same age. This is because of the rapid decline in oestrogen levels during menopause which results in an increased rate of loss of bone calcium and other minerals. This results in approximately 2% bone loss per year occurring for several years post menopause. The rate of hospitalisation for minimal trauma fracture is 2.6x higher for women over 50 compared to men.
Risk factors for osteoporosis
There are a number of risk factors associated with the development of osteoporosis including:
- Increase in age
- Being female
- Having an early menopause or being postmenopausal due to the rapid decline in oestrogen levels
- Family history of osteoporosis
- Reduced levels of oestrogen
- Low calcium intake
- Low levels of vitamin D (which your body needs to absorb calcium)
- Low body weight or small frame
- Lack of physical activity
- Excessive alcohol consumption
- Medical history including: malabsorption disorders (e.g. coeliac disease), some hormonal disorders (e.g. thyroxine excess) or long-term use of certain medications (e.g. corticosteroids)
Symptoms and resulting issues
Osteoporosis usually has no signs or symptoms until a fracture occurs, hence why it is known as a ‘silent disease’. Osteoporosis (and the associated fractures) can result in:
- Increased risk of fractures
- Loss of height
- Severe back pain
- Change of posture
- Muscle weakness
- Spinal bone deformity
- Impaired ability to walk
- Chronic pain
- Loss of independence
- Premature death
Diagnosis of osteoporosis
Osteoporosis is often referred to as a silent disease as it can progress undetected for many years until a fracture occurs. It is diagnosed using a bone mineral density test (also known as a ‘dual energy X-ray absorptiometry (DXA) scan’) to measure the bone mineral density in the hips and spine. The results of the scan will be compared to the average BMD of healthy adults and expressed the as a T-score. The range of T-scores will determine whether the individual’s bone density is normal or an indication of osteopenia or osteoporosis (See Table 1).
Table 1: How T scores relate to bone density health
|Normal||1 to -1|
|Osteopenia||-1 to -2.5|
|Osteoporosis||-2.5 or lower|
Prevention and management of osteoporosis
The best prevention methods depend on your bone density and T-score results. If the test shows normal bone density recommendations for maintaining good bone health include exercise and adequate intake of calcium and vitamin D. If the test shows osteopenia further lifestyle changes may be required as well as a follow-up bone density scan in 1-2 years to monitor your bone health. If the results show osteoporosis it means you are at risk of fracture and important lifestyle changes and fall prevention measures need to be taken. You’ll also likely start treatment to prevent further bone loss and fractures and require a follow-up test in a year’s time. It is essential that any osteoporotic fractures are identified and treated as quickly as possible in order to stop the fracture cascade.
Additional modifications to day-to-day behaviour can prevent or slow down the development of osteoporosis, or lessen the effects of the disease. These include:
- Increasing calcium intake through diet or supplements
- Increase vitamin D levels with sunlight exposure or supplements
- Partaking in regular weight-bearing exercise
- Stopping smoking
- Decreasing alcohol intake
- Possible changes in your normal medications
- Adjusting behaviour to avoid fractures wherever possible
Bone tissue is constantly broken down (by osteoclasts) and renewed (by osteoblasts) in a carefully balanced cycle. Osteoporosis unbalances this cycle. Medications for managing osteoporosis inactivates osteoclasts to stop bone tissue breakdown, but allows osteoblasts to continue forming new bone tissue. This results in a gradual increase in bone tissue density over time.