Osteoporosis
Definition
Osteoporosis = reduced bone mass that leads to increase in bone fragility and susceptibility to fracture
Epidemiology
230,000 osteoporotic fractures in the UK each year
Prevalence in >50 yrs: male = 6%, female = 18%
Aetiology
RA
BMI <22
Parental history
Prolonged immobility
Age
Untreated menopause - in menopause there is loss of restraining effects of oestrogen on bone turnover
Risk Factors
Thin - BMI<22
Testosterone low
Alcohol + tobacco use
Early menopause
Hyperthyroidism, hyperparathyroidism
Renal or liver failure
Steroid use (5mg/d prednisolone)
Erosive bone disease - RA, myeloma
SHATTERED
Dietary low calcium
Pathophysiology
In ageing, there is decreased trabecular thickness and a decrease in connections between horizontal trabeculae
This leads to decrease in trabecular strength and increased susceptibility to fracture
There is high bone turnover: resorption > turnover. Inflammatory cytokines and cortisol increase bone resportion
Signs
Crush fractures of vertebrae if trabecular bone is affected
Long bone fractures if cortical bone is affected
Investigations
X-ray
Bloods: calcium, phosphate and alkaline phosphate all normal
DEXA scan to measure bone mineral density.
1 = normal
-1 to -2.5 = osteopenia
<-2.5 = osteoporosis
FRAX score to estimate 10 year risk of osteoporotic fracture in untreated patients
Treatment
Lifestyle Changes
Weight bearing exercise
Pharmacological
Calcium + vitamin D
Calcium and vitamin D rich diet
Reduce alcohol consumption
Balance exercises
Quit smoking
Denosumab - monoclonal antibody to RANK ligand, reduces risk of fracture
Bisphosphonates e.g. alendronate - decreases bone resorption
Hormone replacement therapy - reduces risk of fractures + stops bone loss. Increases risk of breast cancer + stroke
Teriparatide - PTH analogue, good for those who suffer further fractures despite treatment