What is osteoporosis?

Osteoporosis (meaning 'porous bones') is a condition that causes bones to become thin, weak and fragile. As a result, even a minor bump or accident can cause a fracture (broken bone). Such events might include falling out of a bed or chair, or tripping and falling while walking. Fractures due to osteoporosis can result in chronic pain, disability, loss of independence and premature death [1].

diagram showing healthy bone versus osteoporosis

 

Decreased bone density occurs when bones lose minerals such as calcium faster than the body can replace them. The decrease in bone mineral density (BMD) and changes in bone quality make bones more fragile and more easily broken than bones of 'normal' density. Low bone density is known as osteopenia and is the range of bone density between normal bones and osteoporosis.

Risk factors associated with the development of osteoporosis include increasing age, female sex, family history of the condition, low vitamin D levels, low intake of calcium, low body weight, smoking, excess alcohol consumption, physical inactivity, long-term corticosteroid use and reduced oestrogen level [2]. Osteoporosis is also common in people with malabsorption disorders such as coeliac disease and with certain hormonal disorders such as thyroxine excess.

Diagnosing osteoporosis

Diagnosis of osteoporosis requires a specialised X-ray known as a 'Dual energy X-ray Absorptiometry (DXA) scan' to determine the BMD in hips and spine. Scan results are expressed as T-scores which compare a person's BMD with the average of young healthy adults.

Table 1: Diagnosing osteoporosis using bone density testing

  Normal Osteopenia Osteoporosis
T-Score   1 to –1 –1 to –2.5 –2.5 or lower

Source: WHO Study Group 1994 [3].

Managing osteoporosis

Osteoporosis is managed using medicine, behaviour modification and medical care. Medicines for managing osteoporosis include drugs that reduce bone breakdown, which must be administered regularly. These include oral bisphosphonates such as alendronate and risedronate, intravenously administered bisphosphonate (zoledronic acid), and an injection given under the skin (denosumab) [4]. People with osteoporosis are encouraged to prevent fractures by avoiding falls. When fractures do occur they should be managed promptly, in particular hip fractures [5].

Quality of life can be severely compromised for people with osteoporosis, particularly if they fall and sustain a fracture. Wrist and forearm fractures may affect the ability to write or type, prepare meals, perform personal care tasks and manage household chores. Fractures of the spine and hip can affect mobility, making activities such as walking, bending, lifting, pulling or pushing difficult. Hip fractures, in particular, often lead to a marked loss of independence, and reduced wellbeing.

Osteoporosis is largely a preventable disease. Primary prevention includes getting enough calcium and vitamin D, keeping physically active, maintaining a healthy weight, keeping alcohol intakes low and not smoking [2].

References

  1. Bliuc D, Nguyen ND, Nguyen TV et al. 2013. Compound risk of mortality following osteoporotic fracture and refracture in elderly women and men. Journal of Bone and Mineral Research 28(11):2317–2324.
  2. Ebeling PR, Daly RM, Kerr DA et al. 2013. Building healthy bones throughout life: an evidence-informed strategy to prevent osteoporosis in Australia. Medical Journal of Australia Open 2 (Supplement 1):1–46.
  3. WHO (World Health Organization) Study Group 1994. Assessment of fracture risk and its application to screening for postmenopausal osteoporosis. WHO Technical Report Series 843:3–5.
  4. NPS (National Prescribing Service) 2011. Reducing fracture risk in osteoporosis. Sydney.
  5. RACGP (The Royal Australian College of General Practitioners) 2010. Clinical guideline for the prevention and treatment of osteoporosis in postmenopausal women and older men. Melbourne: RACGP.