[2] Osteoporosis Flashcards
Is osteoporosis common?
Yes
What proportion of women over 50 will sustain an osteoporotic fracture in their lifetime?
1/3
What % of people with a hip fracture die within a year?
33%
What % of people will require help to walk 1 year after a hip fracture?
35%
How much do hip fracture cost the NHS per year?
£2 billion
How many hip fractures are there per year?
75,000
What is osteoporosis defined as?
Progressive loss of bone mass associated with changes in bone micro-architecture
What pathological process is osteoporosis linked with?
Reduced cross-linking within the trabecular bone, resulting in cortical thinning
What is remodelling?
The normal process continually taking place within bone
Why is bone remodelling an essential process?
Because it allows bone to adapt to stressors and repair microdamage
What is bone remodelling the net product of?
Bone formation and resorption
What is involved in bone remodelling?
- Activation of osteoclasts from circulating precursor-cells
- Aggregation and adherence of osteoclasts to regions of active bone reabsorption on the trabecular plate
- Osteoclastic breakdown of bone matrix
- Simultaneous osteoblastic deposition of osteoid with subsequent mineralisation
What mediates the activation of osteoclasts from circulating precursor cells in bone remodelling?
Receptor binding of NF-kappaB (RANK) ligand
What does the osteclastic breakdown of the bone matrix release in bone remodelling?
- Calcium
- Minerals
- Active growth factors
What causes mineralisation of newly deposited osteoid in remodelling?
Calcium and phosphate deposition
What happens to the remodelling process in post-menopausal women?
There is a shift towards bone resorption, leading to net bone loss
What happen to the function of osteoclasts in postmenopausal women?
They function in a less regulated manner
What is the result of the osteoclasts functioning in a less regulated manner in postmenopausal women?
They perforate through the trabecular plate
What is the result of osteoclasts perforating through the trabecular plate in post-menopausal women?
There is no framework for osteoblast activity and structural integrity is lost
What are the risk factors for primary osteoporosis?
- Female gender
- Previous fragility fracture
- Maternal history of hip fracture
- Current smoker
- Alcohol intake >3 units/day
- Glucocorticoids >3 months at more than 5mg/day
- Low calcium and vitamin D deficiency
- Low BMI
What are the causes of secondary arthritis?
- Rheumatoid arthritis
- Hyperthyroidism/hyperparathyroidism
- Premature menopause
- Chronic malabsorption or malnutrition, e.g. coeliac
- Chronic liver disease
What is the FRAX tool?
A free online resource developed WHO to calculate the 10-year fracture risk
Why can calculating the 10-year fracture risk be helpful?
It can help inform decisions about treatment alongside investigations
What investigations are done in osteoporosis?
- Blood tests
- Imaging
What blood tests should be done in osteoporosis?
- FBC
- U&Es
- LFTs
- TFT
- Ca
- PO4
- Vitamin D
- PTH
- Coeliac serology
- Myeloma screen
What imaging may be done in osteoporosis?
- DEXA scanning
- Whole-spine x-ray
What is the gold standard diagnosis to establish a formal diagnosis of osteoporosis?
Dual energy X-ray absorptiometry (DEXA) scanning
How does DEXA scanning help establish a diagnosis of osteoporosis?
By measuring bone mineral density (BMD)
What is DEXA scanning reported as?
- T score
- Z score
What does the T score correspond to in DEXA scanning for osteoporosis?
The number of standard deviations above or below the bone mineral density for an average 25-year
What T-score represents osteoporosis?
2.5SDs below normal
What does the Z-score correspond to in osteoporosis?
The number of SDs above or below the bone mineral density in age-matched controls
What kind of fractures can DEXA be used to identify?
Moderate to severe wedge or compression fractures
How can DEXA scanning identify moderate to severe wedge or compression fractures?
It can provide morphometric measurements of the individual vertebrae
Why might a whole spine x-ray be useful in osteoporosis?
Can help identify the presence of asymptomatic fractures
What proportion of vertebral fractures in osteoporosis are asymptomatic?
1/3
What investigation into osteoporosis can be used in specialist clinics?
Bone turnover markers such as serum C-terminal telopeptide (CTX) levels
What can bone turnover markers be useful for in osteoporosis?
To establish compliance and effectiveness of treatment
What management should be commenced in all patients with osteoporotic fractures, or at risk of sustaining them?
Vitamin D supplementation
Is calcium co-administered with vitamin D supplementation in people at risk of osteoporotic fractures?
Depends on baseline serum calcium levels and dietary intake
What is the mainstay of treatment in osteoporosis?
Bisphosphonates
What do bisphosphonates do?
They inhibit osteoclastic bone reabsorption
How does the inhibition of osteoclastic bone reabsorption help in osteoporosis?
Because the processes are linked, impaired bone reabsorption results in reduced bone formation and turnover as a whole is reduced
How long do patients usually receive bisphosphonates?
3-5 years
What is the risk of keeping a patient on bisphosphonates for more than 3-5 years?
Risk of atypical subtrochanteric fracture and osteonecrosis of the jaw
What is required if you want to keep a patient on bisphosphonates for more than 3 years?
Reassessment of fracture risk and up to date BMD measurements
What BMD measurements would support the continuation of treatment?
T score or -2.5, or -2.0 if in conjunction with established vertebral fractures - indicates continued risk of fractures
What other drugs may be used for osteoporosis?
- Zolendronic acid
- Denosumab
- Raloxifene
- Teriparatide
Give an example of an oral bisphosphate?
Alendronate
What are the indications for alendronate?
- Fragility fracture >75 years of age
- Post-menopausal women
What sites benefit from alendronate?
- Hip
- Verteral
- Non-vertebral
