Lecture 26: Bone Health, Falls and Fractures Flashcards

1
Q

The human skeleton is initially…

A

Cartilage and fibrous membranes

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2
Q

By what age is the skeleton completely hardened?

A

25

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3
Q

How many bones make up the adult skeleton?

A

206 (20% of body mass)

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4
Q

What are osteoclasts?

A

Break down bone

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5
Q

What are osteoblasts?

A

Build bone

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6
Q

Osteoclasts tear down and osteoblasts build bone throughout the lifespan with the processes of….

A

Resorption and deposition

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7
Q

What percent of bone calcium is exchanged annually?

A

Average 3% to 5%

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8
Q

What is bone resorption?

A

Action of osteoclasts and parathyroid hormone

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9
Q

What is bone deposition?

A

The action of osteoblasts and calcitonin

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10
Q

What is homeostasis of bone tissue regulated by?

A

Thyroid and parathyroid glands

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11
Q

When blood calcium levels increase…

A
  • Receptors in thyroid gland sense increase
  • Thyroid gland releases calcitonin
  • Osteoblasts deposit calcium in bones
  • Blood calcium is returned toward normal
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12
Q

When blood calcium levels decrease…

A
  • Receptors in parathyroid gland sense decrease
  • Parathyroid gland releases parathyroid hormone
  • Osteoclasts break down bone releasing calcium
  • Blood calcium is returned toward normal
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13
Q

What are the most important factors affecting bone development, growth and repair?

A
  • Calcium deficiency
  • Vitamin D deficiency
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14
Q

What does calcium deficiency result in?

A

Fragile bones

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15
Q

What does vitamin D deficiency result in?

A

Rickets, osteomalacia

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16
Q

When are rates of bone growth the highest?

A

Infancy and pubertal growth spurt

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17
Q

Why is adolescence a critical period in peak bone mass?

A
  • Velocity of bone growth doubles
  • 40% of the peak bone mass is laid down
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18
Q

What happens at the end of puberty?

A

The epiphyses fuse and linear growth stops

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19
Q

Bone mass continues to increase from age 20 to…

A

25 to 30 - 90-95% of peak bone mass attained

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20
Q

After your mid-30s…

A

You slowly lose bone mass

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21
Q

What are determinants of bone strength?

A
  • Bone mineral density
  • Bone Geometry
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22
Q

What is the most important effect of stress on bone?

A

Strain

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23
Q

What is strain?

A

Measurement of deformation of bone to external load

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24
Q

What is strain magnitude?

A

External load

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25
What is strain rate?
Speed of loading
26
Is remodelling reversible?
Yes
27
Peripheral skeleton bone strength is positively correlated with...
Total and dairy protein intakes in healthy postmenopausal women
28
What three alterations of protein use in older persons cause loss of functionality?
- inadequate intake of protein - reduced ability to use available protein - greater need for protein
29
What are overarching stratagies to maximise and protect bone mass?
- Achieve peak bone mass in childhood and adolescence - Maintain bone mass during adulthood - Slow bone loss and reduce falls and fractures in older adults
30
What is osteoporosis?
weakened bones and decreased bone density
31
How many NZ'ers are currently aged over 50 years?
More than 1.6M
32
Osteoporosis NZ estimates how many older Kiwis have broken a bone since their 50th birthday?
Over 180,000
33
How many people annually sustain a hip fracture?
3,700
34
How many people annually are admitted to hospital with other fractures?
13,800
35
What are the different types of osteoporosis?
- Age associated/post menopausal - Idiopathic - Secondary
36
What are the risk factors of osteoporosis?
- Age - Sex - Genetics - PA - Hormones - Diet (Ca, Vit D) - Smoking - Alcohol (3+ units/day)
37
What is secondary osteoporosis?
osteoporosis caused by specific disease, genetics, medical conditions, medications, or lifestyle factors that interfere with bone density and strength, rather than age or menopause
38
What are the risk factors of secondary osteoporosis?
- Disease/genetics - Surgery - Bedrest
39
The development of osteoporosis is inversely related with...
Maximum bone accumulated during growth
40
The development of osteoporosis is positively related with...
the rate and duration of bone loss with ageing
41
What percent of hip fractures are due to falls?
>95%
42
What is the 5th leading cause of death and traumatic brain injury in older adults?
Falls
43
What percent of older people who fall can't get up "long lie"?
50%
43
What percent of those over 80 and those in a care facility will fall each year?
50%
44
What percent of older adults with hip fractures will not return to pre-functional status?
25-75%
45
What are risk factors for falls?
- Muscle weakness - Poor balance - Low PA - Poor eyesight - Benzodiazepine use - Poor overall health - Unsafe enviornment
46
What are risks for a fracture in a fall?
- Failure to break a fall - Falling to the side - Age - Low bone mass - Unfavourable bone geometry - High bone turnover
47
A prior fracture at any skeletal site....
Doubles future fracture risk
48
What are the two pathways to fracture?
Mechanical overload and incompetence
48
When does a second fracture often happen?
Within 6-8 months
49
What is mechanical overload caused by?
Sarcopenia
50
What is mechanical incompetence caused by?
Osteoporosis
51
Vitamin D has an important role together with calcium in...
Mineral metabolism and bone growth maintenance
52
Most cells in the body have been found to have...
receptors for vitamin D, and is therefore now seen as an important nutrient in preventing many chronic diseases
53
Major trials in community-dwelling individuals have not demonstrated fracture prevention with either...
Calcium, vitamin D or their combination
54
Trials show vitamin D supplements increase...
Bone density
55
Clinical trials have not demonstrated benefits of vitamin D on...
non-skeletal endpoints (e.g. muscle mass or function)
56
Calcium supplements in healthy individuals are...
not needed
57
Overall, current evidence does not support the use of...
Vitamin D or Ca+ supplements in healthy adults although it may be warranted in frail older adults in nursing homes with low Vit D
58
In VITAL, supplementation with 2000IU/d of vitamin D...
Did not reduce the risk of hip fractures
59
In what populations might findings that supplementation did not have health benefits be different?
Individuals with: - very low 25(OH)D (Vit D) levels - GI disorders causing malabsorption - those with osteoporosis
60
Osteoporosis and sarcopenia are linked to...
Nutritional deficits and reduced function in geriatric inpatients
61
What is osteosarcopenia?
the coexistence of osteoporosis (reduced bone density) and sarcopenia (loss of muscle mass and strength) in older adults
62
What is osteosarcopenia associated with?
A higher degree of malnutrition than osteoporosis or sarcopenia alone