Disorders of Bone Health Flashcards
common fracture sites?
neck of femur
vertebral body
distal radius
humeral neck
what usually causes a colles fracture?
fall onto outstretched hand
why does osteoporosis cause a curvature of the spine (e.g thoracic kyphosis, loss of height)?
crumbing of vertebrae/wedge fractures in vertebrae
what is the most common osteoporotic fracture?
colles in younger
hip in elderly
how can bone density be assessed?
BMD (predicts fracture risk independently of other risk factors)
DEXA scan = most commonly used method of measuring BMD
how is DEXA scan used?
compares to other people of same age
= Z score
compares to young adult average
= Gives T score (<2.5 = osteoporosis)
what is a normal BMD?
within 1 standard deviation of the young adult reference average
osteopaenia BMD?
> 1 standard deviation below young adult mean but <2.5 SD below this value
osteoporosis BMD?
2.5 or more SD below young adult mean
severe osteoporosis = >2.5 below with a fragility fracture
which score is used if under 20?
only Z score
who should be refered for a DEXA scan?
patients over 50 with a low trauma fracture (often identified through fracture laison service)
patients at increased risk of fracture based on risk factors (calculated using risk assessment tool - FRAX or Qfracture - if >10% fracture risk over 1 years
SIGN objectives of osteoporosis management?
address risk factors for fracture (modifiable and non-modifiable)
assess fracture risk (use tools)
non modifiable fracture risk factors?
age gender ethnicity previous fracture family history menopause <45 co-existing disease
modifiable risk factors for fracture?
BMD alcohol weight smoking physical inactivity pharmacological
what is the WHO fracture risk calculator?
calculates absolute risk by incorporating additional risk factors rather than just BMD
predicts 10 year fracture risk
who should be assessed with risk fracture assessment (Qfracture or WHO calculator)?
over 50 with risk factors
under 50 with very strong clinical risk factors (early menopause, glucocorticoids)
slide 41 algorithm
/…
what tests are done for osteoporosis?
history and examination Us&Es LFTs bone biochemistry FBC PV TSH consider - Protein electrophoresis/Bence Jones proteins Coeliac antibodies Testosterone 25OH Vitamin D PTH
name 4 secondary causes for osteoporosis
endocrine (hyperthyroid, hyperparathyroid, cushings)
GI (coeliac, IBD, chronic liver disease, chronic pancreatitis)
resp (CF, COPD)
chronic kidney disease
general lifestyle advice for osteoporosis?
High intensity strength training Low-impact weight-bearing exercise (standing, one foot always on the floor) Avoidance of excess alcohol Avoidance of smoking Fall prevention
describe the osteoporotic diet?
RNI 700mg calcium (2-3 portions from milk and dairy foods group)
Postmenopausal women aim dietary intake 1000 mg calcium per day to reduce fracture risk (3-4 portion calcium rich foods)
Non-dairy sources include
bread and cereals (fortified)
fish with bones, nuts,
green vegetables, beans
what drug treatments are available for osteoporosis?
Calcium & vitamin D supplementation Bisphosphonates Denosumab Teriparatide HRT SERMS (Selective Estrogen Receptor Modulators) Testosterone
when are calcium and vit D supplements used? (SIGN guidelines)
… slide 47
what are bisphosphonates and what do they do?
Anti-resorptive agents – alendronate and risedronate
Prevent bone loss at all sites vulnerable to osteoporosis and Reduce risk of hip and spine fracture
…..
bisphosphonates
……
bisphosphonates
………
bisphosphonates
……..
how is zoledronic acid used?
Once yearly IV infusion for 3 years
5 mg in 100 ml NaCl over 15 mins
1 in 3 acute phase reaction with first infusion – paracetamol
~ 70% reduction in vertebral fracture, 40% reduction in hip fracture
what is denosumab and what does it do?
Denosumab – fully human monoclonal antibody that targets and binds with high affinity and specificity to RANKL (receptor activator of nuclear factor-kB ligand)
This prevents activation of its receptor, RANK, inhibiting development and activity of osteoclasts, decreasing bone resorption and increasing bone density.
how is denosumab given?
Subcutaneous injection 6 monthly
what are the side effects of denosumab?
hypocalcaemia
eczema
cellulitis
(no impact on renal impairment)
what is teriparatide and what does it do?
Recombinant parathyroid hormone (1-34)
Stimulates bone growth rather than reducing bone loss – anabolic agent
when is teriparatide used?
> 65y with T score < -4 or below
T score of – 3.5 plus > 2 fractures
Aged 55-64y with T score -4 or below plus more than 2 fractures ( plus intolerant/unsatisfactory response to oral agents)
when is osteoporosis treated?
antiresorptive treatment when T score = -2.5
If ongoing steroid requirement >/=7.5mg prednisolone for 3 months or more or if there is a prevalent vertebral fracture, consider treatment with T score < -1.5
what are the direct effects of corticosteroids on bone?
Reduction of osteoblast activity and lifespan
Suppression of replication of osteoblast precursors
Reduction in calcium absorption
what are the indirect effects of corticosteroids on bone?
Inhibition of gonadal and adrenal steroid production
what 4 systems can glucocorticoids effect?
…..slide 59
how does steroid dose relate to fracture risk?
individual variability to glucocorticoids
dose dependant fracture but no safe dose
rapid loss of BMD (30% in first 6 months)
- partially reversible on cessation of treatment
different fracture threshold so different treatment threshold
why are osteoporotic fractures dangerous?
with every fracture, the risk of further fractures is increased
neck of femur fractures have high morbidity and mortality
what is pagets disease of bone?
abnormal osteoclastic activity followed by increased osteoblastic activity resulting in abnormal bone structure with reduced strength and increased fracture risk
can be monostotic or polyostotic (single or multiple sites)
what can trigger pagets disease?
viral
environmental
biomechanical
in genetically predisposed individual
where does pagets mostly affect?
long bones
pelvis
lumbar spine
spine
how does pagets present?
bone pain deformity deafness compression neuropathy osteosarcoma is a rare complication
how is pagets diagnosed?
incidental finding on X ray or isolated high Alk Phos
diagnosis = X ray
isotope bone scan shows distribution of disease
biochem shows raised alk phos with normal LFTs
how is pagets managed?
bisphosphonates if pain not responding to analgesia
what is osteogenesis imperfecta?
rare group of genetic disorders mainly affecting bone
what causes osteogenesis imperfecta?
most are secondary to mutations of type 1 collagen genes
most are autosomal dominant
what are the types of osteogenesis imperfecta?
at least 8 types
- type 1 = mild
- type 2 = neonatal (lethal)
- types 3 and 4 = very severe
how does osteogenesis imperfecta?
most severe forms = fractures in childhood
mild = may not present until adulthood
blue sclera
dentinogenesis imperfecta
how is osteogenesis imperfecta managed?
no cure
only fracture fixation, surgery to correct deformity
bisphosphonates
//
//
/
/
/
/
/
/
/
/
/
/
/
/
/
/r
/
/
/
/
/
/y
