Osteoperosis

Question 1

What are osteoprogenitor cells?

Answer 1

Stem cell population, gives rise to osteoblasts.

Question 2

What are osteoblasts?

Answer 2

Responsible for bone formation, cover the surface of bone.

Question 3

What are osteocytes?

Answer 3

Mature bone cells - embedded in lacunae, relatively inactive. Maintain bone matrix through cell-to-cell communication and influence bone remodelling. Mechanosensing

Question 4

What are osteoclasts?

Answer 4

Multinucleated, derived from haematopoietic cells. In response to mechanical stresses and physiological demands they resorb bone matrix by demineralization.

Question 5

How many people does osteoporosis affect?

Answer 5

• 1in3women

* 1in12men

Question 6

What does osteoporosis do to bone structure?

Answer 6

Decreased size of osteons Thinning of trabeculae

Enlargement of Haversian and marrow spaces

Question 7

What are the two classifications of osteoporosis?

Answer 7

Type 1 - Post menopausal

Type 2 - Age related in those over 75 years

Question 8

Discuss Type 1 osteoporosis

Answer 8

• Affects mainly cancellous bone
• Vertebral and distal radius fracture is common
• Related to loss of oestrogen
• F:M = 6:1

Question 9

Discuss Type 2 osteoporosis

Answer 9

• Affects cancellous and cortical bone
• is related to poor calcium absorption
• Hip and pelvic fractures common
• F:M=2:1

Question 10

What is disuse osteoporosis?

Answer 10

Conditions resulting in prolonged immobilisation, typically in neurological or muscle disease
Also astronauts

Question 11

What are the clinical consequences of osteoporosis?

Answer 11

Increase in bone fragility Susceptibility to fracture:
micro- or fragility fracture

Fragility fracture
– “Low energy” trauma
– Mechanical forces that would not ordinarily cause fracture – WHO: ≈ “fall from a standing height or less”

Question 12

Discuss the consequences of hip fractures

Answer 12

• Fatal in 20-30% of cases
• Only 30% fully recover
• Permanently disables 50%

Question 13

Where are the common sites of osteoporotic fractures

Answer 13

Proximal humerus, distal radius, spine, femoral neck, vertebral body

Question 14

What can you use to assess patient risk for osteoporosis?

Answer 14

FRAX - the who fracture risk assessment tool

Question 15

What are the risk factors for osteoporosis?

Answer 15

Genetic/biological sex Lifestyle/nutritional
Medical conditions Medications
Previous fragility fracture

Question 16

Discuss race and ethnicity in osteoporosis

Answer 16

– Prevalence ~50% lower in black Americans than white
– Rates of fragility fractures in the UK 4.7x greater in
white compared to black women
– In US, black women less likely to receive treatment or be screened, plus associated with worse outcomes following fracture
– Latin Americans at highest risk of fractures in US, and less likely to take preventative steps
– Chinese women have lower BMD, but lower rates of hip and spine fractures

Question 17

Discuss trans patients and osteoporosis

Answer 17

– Adherence to gender-affirming hormone replacement therapy (GAHT) may protect BMD of both trans women and trans men
– Trans women tend to have lower BMD prior to initiation of GAHT
– Sparse data on impact of GAHT on fracture risk in both trans women and men
– Currently unclear what impact puberty blockers have on bone mass and fracture risk

Question 18

What lifestyle/nutritional factors may impact osteoporosis?

Answer 18

Smoking
Excess alcohol
Sedentary
Prolonged immobilisation

Question 19

What medical conditions may impact osteoporosis?

Answer 19

A ton really

Anorexia nervosa
Rheumatoid arthritis
Early menopause <45 years of age
Primary hypogonadism
Secondary amenorrhoea for more than 1 year Hyperthyroidism
Primary hyperparathyroidism
Multiple myeloma
Transplantation
Chronic renal, pulmonary or gastrointestinal disease Cushing’s disease/syndrome

Question 20

What drugs may impact osteoporosis?

Answer 20

Chronic corticosteroid therapy (can increase risk of fracture by 2-3x)
Excessive thyroid therapy
Gonadotrophin releasing hormone agonist or antagonist Anticoagulants
Anticonvulsants
Chemotherapy

Question 21

Is the risk of another fracture after a previous fragility fracture greater than that of the initial fracture?

Answer 21

Ye
A previous wrist fracture:
Doubles the risk of a future hip fracture Triples the risk of future vertebral fracture

Question 22

What investigations should one complete for suspected osteoporosis?

Answer 22

Blood tests, FBC, serum biochemistry, bone profile
Thyroid function tests
Testosterone and gonadotrophin levels in men

X-ray of lumbar and thoracic spine
• >30 % of bone loss required to be visible

Bone mineral density measurement

Question 23

What is a DEXA?

Answer 23

Dual-energy x-ray absorptiometry scan

Low-dose x-rays with two distinct energy peaks (one absorbed by soft tissue and the other by bone)

Question 24

How do you calculate a patients bone mineral density (BMD) form a DEXA?

Answer 24

Low-dose x-rays with two distinct energy peaks (one absorbed by soft tissue and the other by bone)
Subtracting one from the other gives a patient’s bone mineral density (BMD)

Question 25

Discuss DEXA scores

Answer 25

T score
Comparison with a young adult of the same sex with peak bone mass:

T-Score : Classification
> -1 : Normal
-1 to -2.5 : Osteopenia (bone thinning)
< -2.5 : Osteoporosis

Z score
Comparison of the patient’s BMD with data from same age/sex/size.

Question 26

Discuss treatment of osteoporosis

Answer 26

Bisphosphonates
• e.g. alendronate, risedronate
• disrupt the activity of osteoclasts
• potential side effects – oesophagitis, mandibular necrosis

Anabolic agents
• e.g. intermittent PTH, strontium ranelate

Ca++ supplements

Hormone replacement therapy
• carries an increased risk of breast cancer

Increase exercise