MSK: Part 2 Flashcards
Define Osteoporosis
- A systemic skeletal disease characterised by low bone mass and a micro architectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture
What parameters define osteoporosis
Defined as Bone mineral density MORE than 2.5 SDs below young adult mean value (T score < 2.5)
What is Osteopenia
Pre-cursor to osteoporosis characterised by lone bone density
What parameters define osteopenia
BMD between- 1 to -2.5 SDs below young adult mean value (-1
What is Osteomalacia
poor bone mineralisation leading to soft bone due to lack of Ca2+ (adults form of rickets)
How is T score calculated
SD score ascertained using DEXA scan
Compared to gender-matched young adult average (peak bone mass)
What is a normal T score
-1
In what gender is osteoporosis more common in and why
FEMALES
They lose trabculae over time
Risk factors for osteoporosis
- Old age
- Women
- Family history of osteoporosis or fracture
- Previous bone fracture
- Smoking/Alcohol
SHATTERED: S - STEROID USE (PREDNISOLONE) H - HYPERTHYROIDISM A- Alcohol and tobacco (bad for bones T - Thin (BMI <22) T - Testosterone E- Early Menopause R - Renal or liver failure E - Erosive/inflammatory bone disease (Myeloma) D - Dietary (calcium malabsorption)
What is the peak bone mass age
25
How does osteoporosis happen
Increased bone breakdown by osteoclasts and decreased bone formation by osteoblasts leading to loss of bone mass
What is the biggest influence on peak bone mass
genetic factors
What genes are responsible for peak bone mass
Collagen type 1A1
Vit D receptor
Oestrogen receptor genes
What determines bone strength
BMD - How much mineral in bone (determined by gained during growth and amount lost during ageing)
Bone size - Short and fat better than long and thin
Bone Quality - Bone turnover rate
What causes postmenopausal osteoporosis
Increased numbers of osteoclasts, premature arrest of osteoblastic synthetic activity
Perforation of trabecular with loss of resistance to fracture
High bone turnover (resorption greater than formation)
Predominantly cancellous bone loss
How does trabecular architecture change with ageing
Decrease in trabecular thickness - as we age the strain is felt on bones from head to tail, in response, we tend to preferentially preserve vertical trabecular and lose horizontal trabecular
Decrease in trabecular thickness in connections between horizontal trabecular resulting in decrease trabecular strength and increased susceptibility to fracture
Clinical presentation of osteoporosis
- Fractures!!
Vertebral crush fracture
Colles’ fracture of wrist following outstretched arm
Fractures on proximal femur usually occur in older individuals falling on their side or back
What is vertebral crush
Sudden onset of severe pain in the spine, radiating to the front
Thoracic vertebral fractures may lead to kyphosis (widows stoop)
How is osteoporosis diagnosed
- X-ray
- DEXA scan
- Bloods
What do x-rays show for osteoporosis
Demonstrate fractures but insensitive for osteopenia
What is DEXA
- Measures important fracture sites (lumbar spine and proximal femur)
- GOLD STANDARD - measures bone density and diagnosis
- Generates T scores
What T-score equals Osteoporosis
more than 2.5 SDs
Blood tests in osteoporosis
- Ca
- Phosphate
- Alkaline phosphate all normal
How is osteoporosis treated
- Quit smoking and alcohol
- Weight-bearing excersise (increases bone density)
3/ Calcium and vit D rich diet - Balance excercises to reduce falls
First line treatment for osteoporosis
Bisphosphanates
How do bisphosphonates work
Inhibit bone resorption through inhibition of enzyme (Farnesyl Pyrophosphate synthase - in cholesterol pathway) which reduces osteoclastic activity by removing their ruffled border
Increases bone mass at hip and spine
Reduce incidence of fracture and are cheap and effective
Name a bisphosphonate
ORAL ALDENRONATE
ORAL ZOLENDRONATE
When are oral bisphosphonates given
When fasting, with a large drink of water while standing or sitting upright
Associated with oesophagi’s
Name two anti-resorptive drugs other than bisphosphonates
- STRONTIUM RENELATE
2. DENOSUMAB
What is Strontium Renovate
Helps reduce fracture rates
When is Strontium renovate given
Alternative to those intolerant to bisphosphonates
How do DENOSUMABs work
- Osteoblasts produce RANK to activate osteoclasts and thus bone respiration
What is DENOSUMAB
Monoclonal antibody that inhibits RANK signals
2nd line treatment of osteoporosis
HRT (Hormone Replacement Therapy)
for menopausal women
Role of HRT
Reduces fracture risk and stops bone loss
Prevents hot flushes and other menopausal symptoms
Side-Effect of HRT
Breast cancer
Stroke
CVD
What is RALOXIFINE
Selective Oestrogen receptor modulator - activates oestrogen receptor on bone whilst having no stimulatory effect on endometrium
Side-effects of RALOXIFINE
- Increased risk of thrombus formation
- Cramps
- Strokes
What HRT is used for men in osteoporosis
Testosterone
What anabolic can be used for osteoporosis
- RECOMBINANT HUMAN PARATHYROID PEPTIDE
How does Recombinant human parathyroid peptide function
- Increases osteoblast activity and bone formation
- Reduce fracture risk
- Improves bone density, trabecular structures
Side-Effects of recombinant human parathyroid peptide
Increased risk of renal malignancy
Hypercalcaemia
Name a Recombinant human parathyroid peptide
TERIPARATIDE
Name some inflammatory markers
ESR
CRP
When does ESR raise
Inflammation and infection