Osteoporosis

Osteoporosis is a systemic skeletal disease characterised by:
- Low bone mass
- Micro-architectural deterioration
It is associated with increased bone fragility and susceptibility to fractures
It is defined as a bone mineral density less than 2.5 standard deviations below the mean
Established osteoporosis is a low bone mineral density associated with an osteoporosis-related fracture

Bone undergoes continuous resorption and formation
10% of adult skeleton is remodelled each year
Bone loss results from an imbalance between resorption and formation
Human skeleton comprises approximately
- 80% cortical bone
- 20% trabecular bone
Osteoporotic fractures occur at sites with more than 50% trabecular bone
- Vertebral body
- Proximal femur
- Distal forearm
Bone loss leads to thinning of the trabecular plates
This causes a disproportionate loss of bone strength
Peak bone mass is achieved by the age of 30 years
After skeletal maturity bone is lost at about 1% per year
Women experience accelerated bone loss after the menopause
Factors associated with increased bone loss include:
- Inactivity
- Cigarette smoking
- Poor diet
- Family history
- Early menopause
- Endocrine disease - Cushing's syndrome, diabetes, hyperthyroidism
- Drugs - Steroids, thyroxine, diuretics

Optimisation of peak bone mass
- Exercise
- Dietary calcium
Reduce rate of bone loss
- Hormonal replacement therapy
- Moderate alcohol intake
- Stop smoking

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