Osteoporosis Flashcards

1
Q

What are the seven important functions of bones?

A
  • Support
  • Protect
  • Movement
  • Mineral and growth factor storage
  • Blood cell formation
  • Triglyceride storage
  • Hormone production
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2
Q

What are osteogenic stem cells?

A

Progenitor cells that differentiate into osteoblasts

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3
Q

What part of the bone is most affected by osteoporosis?

A

Cancellous (spongy) bone

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4
Q

What do osteoblasts secrete?

A

Osteoid (unmineralised matrix)

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5
Q

What cells line the bone? What is their role?

A

Periosteal and endosteal cells maintain matrix

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6
Q

What do osteocytes sense?

A

Sense stress and strain

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7
Q

What are the organic components of bone?

A
  • Osteogenic cells
  • Osteoblasts
  • Osteocytes
  • Bone-lining cells
  • Osteoclasts
  • Osteoid
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8
Q

What is osteoid made up of?

A

Ground substances and collagen fibres

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9
Q

What gives bone resilience?

A

Sacrificial bonds in or between collagen molecules

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10
Q

What is the inorganic component of bone? What percentage of the total bone mass does it make up?

A

Hydroxyampatites (mineral salts), 65% of bone mass

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11
Q

What hormones are responsible for regulation of bone growth?

A
  • Growth hormone
  • Thyroid hormone
  • Testosterone and oestrogen
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12
Q

What percentage of bone mass is “recycled” due to bone homestasis each week?

A

5-7%

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13
Q

How often is spongy bone and compact bone replaced by bone homeostasis?

A

Spongy bone: every 3-4 years

Compact bone: every 10 years

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14
Q

Where in the bone does bone remodelling occur?

A
  • Periosteum

- Endosteum

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15
Q

What is the function of osteoclasts?

A
  • Create depressions or grooves as break down of matrix occurs
  • Secretes lysosomal enzymes that digest matrix and protons
  • Acidity converts calcium salts to soluble form
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16
Q

What does osteoclast activation depend on?

A

Parathyroid and thyroid cell-secreted proteins

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17
Q

What are the functions of calcium in the body?

A
  • Nerve impulse transmission
  • Muscle contraction
  • Blood coagulation
  • Secretion by glands and nerve cells
  • Cell division
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18
Q

How much calcium is in the body normally?

A

1200-1400g of calcium in body

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19
Q

What vitamin is required to absorb calcium?

A

Vitamin D

20
Q

What effect does parathyroid hormone have on calcium?

A

Removes calcium from bone, regardless of bone integrity

21
Q

What effect does calcitonin have?

A

In high doses, lowers blood calcium levels temporarily

22
Q

What is involved in the negative feedback hormonal loop for blood calcium homeostasis?

A
  • Calcitonin secreted by the thyroid gland
  • Stimulates osteoblasts and inhibits osteoclasts
  • Blood calcium decreases
  • Parathyroid hormone secreted by parathyroid glands
  • Stimulates osteoclasts and inhibits osteoblasts
  • Blood calcium increases
23
Q

What is osteoporosis?

A

A reduction in bone mineral density 2.5 SD below the young adult mean (age 30)

24
Q

What is osteopaenia?

A

A reduction in bone mineral density 1 - 2.5 SD below the adult mean (age 30)

25
Q

What bone changes occur with the development of osteoporosis?

A

Loss of microarchitecture of bone

  • total bone mass
  • trabecular volume
  • trabecular connectivity/separation
  • trabecular plate thickness, and number
26
Q

How is osteoporosis severity scored?

A

T-score

27
Q

What are the risk factors for osteoporosis?

A
  • Age
  • Post-menopausal women
  • Older men
  • Petite body form
  • Insufficient exercise
  • Poor diet
  • Low Vitamin D and C
  • Smoking
  • Hormone conditions
  • Immobility
  • Prostate cancer (androgen-suppressing drugs)
28
Q

What other pathologies are also considered to increase the risk of osteoporosis?

A
  • Rheumatoid arthritis
  • Coeliac disease
  • Chronic lung diseases
  • Chronic renal failure
  • Chronic liver failure
29
Q

How often is someone admitted to an Australian hospital with an osteoporotic fracture?

A

Every 5-6 minutes

30
Q

How is osteoporosis diagnosed?

A

Dual Energy X-ray Absorptiometry or bone densitometry

31
Q

What sites are used to measure bone density? What kind of fractures are they best at predicting?

A
  • Femoral neck: best site for predicting hip fractures
  • Vertebra: best site for predicting spinal fractures
  • Radius
32
Q

How many women and men over 60 years of age will suffer an osteoporotic fracture in their lifetime?

A
  • 60% of women

- 30% of men

33
Q

What is the incidence of further fracture in women with an osteoporotic spinal fracture?

A

Women with spinal fractures are 4 times more likely to have another fracture within the next year, compared to women who have never had an osteoporotic fracture

34
Q

What are the outcomes after osteoporotic hip fractures?

A
  • 20-25% will be permanently disabled
  • 50% never regain their former independence, and will require long-term nursing care
  • 1 in 3 return to activity and independence
  • 12-15% mortality within 6 months
  • 25% mortality at 12 months as a result of subsequent immobility.
35
Q

What does osteoporosis treatment involve?

A
  • Calcium supplements
  • VItamin D supplements
  • Weight bearing exercise
  • Hormone replacement therapy
36
Q

What drugs are used in the treatment of osteoporosis?

A
  • Bisphosphonates: inhibit osteoclast activity and number
  • Selective oestrogen receptor modulators: mimic oestrogen
  • Parathyroid hormone
  • Denosumab
  • Strontium injections
37
Q

What prevention strategies are used in the management of osteoporosis?

A
  • Maximise peak bone mass
  • Limit the gradient of decline
  • Prevent falls and fractures
38
Q

What are the roles of Vitamin D?

A
  • Regulation of paslam calcium and bone mineralisation
  • Maintains function of neuromuscular junctions
  • Effects on other systems
39
Q

What food sources have Vitamin D?

A

Most: fatty fish
Less: eggs, some low-fat milk, fortified products

40
Q

What does Wolff’s law indicate?

A

Wolff’s law indicates that bone strength increases and decreases as the functional forces on the bone increase and decrease.

41
Q

What are the general principles of exercise for osteoporosis?

A
  • Long term
  • Ongoing, but changing
  • Site specific
  • Tension or force producing
  • Consideration of falls risk, balance and reaction time
42
Q

What aspects need to be considered for exercise prescription in osteoporosis?

A
  • Specificity: site-specific
  • Overload: must exceed typical everyday loads
  • Reversibility
  • Initial values: lower start, progress
  • Diminished returns: quick response, then slow
43
Q

What movements should be avoid by individuals who are severely osteoporotic?

A

Avoid flexion, twisting and asymmetrical loading

44
Q

What did Bailey and Wavell (2010) and Daly et al conclude about weighbearing and impact exercise?

A

Higher frequency and repetitions result in greater bone mineral density

45
Q

What is the incidence of further osteoporotic fractures in those who have already had 2 or more and 3 or more previously, compared to someone who has no previous history?

A

2 or more: 9 times more likely to have another fracture

3 or more: 11 times more likely to have another fracture