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Bone Disorders Flashcards

1
Q

What disease is characterised by a low bone mass causing skeletal fragility and susceptibility to fracture?

A

Osteoporosis

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2
Q

At what distinct sites does bone undergo remodelling?

A

bone remodelling units

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3
Q

What percentage of the adult skeleton is remodelled each year?

A

~10%

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4
Q

Briefly describe the bone remodelling cycle

A
  • osteoclasts appear on a previously inactive surface
  • resorb the bone
  • replaced by osteoblasts in the cavity
  • they put down osteoid that is mineralised to form new bone
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5
Q

Describe the ratio of osteoclasts to osteoblasts in osteoporosis

A

Osteoclasts>osteoblasts

=> more bone breakdown than formation

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6
Q

Describe the differences in micro-architecture between normal and osteoporotic bone

A

Osteoporotic:

  • clear loss of bone
  • large spaces and breaks
  • breaks lead to weakened bones and fractures

Normal bone:
- thick, dense network
- small spaces
=> increased bone strength

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7
Q

At what age do humans achieve their peak bone density?

A

Late 20s

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8
Q

Menopause causes slower age related bone loss. TRUE/FALSE?

A

FALSE

Menopause causes a period of accelerated bone loss

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9
Q

What are the most common fracture sites in osteoporosis?

A

Neck of femur
Vertebral body
Distal radius
Humeral neck

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10
Q

An older lady with osteoporosis falling onto an outstrectched hand is most likely to sustain what type of fracture?

A

Colles fracture

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11
Q

Wedge fractures of the spine can result in what curvature forming?

A

Thoracic Kyphosis

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12
Q

What scan is used to measure bone density?

A

DEXA scan

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13
Q

What bones are measured in a DEXA scan to assess bone density and why?

A

Hip
L1-L4
- as these are most prone to fracture -

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14
Q

Describe the difference between a T score and a Z score on the DEXA scan

A

T score = bone density compared to young adult population average

Z score = compared to population average of the same age as the patient

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15
Q

In what situation would only a Z score be considered ni a DEXA scan?

A

If the patient was <20 years old

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16
Q

How are DEXA results interpreted?

A

Normal if less than 1 standard deviation (SD) below the young adult average

Osteopenia if between 1 and 2.5 standard deviations below the young adult average

Osteoporosis if 2.5 or more standard deviations below

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17
Q

What does 1 standard deviation of seperation in a DEXA scan indicate in terms of fracture risk?

A

Lowering by 1 SD doubles fracture risk

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18
Q

What type of patients should be referred for a DEXA scan?

A

> 50 with low trauma fracture

If at increased risk:
e.g. > 10% risk of fracture over 10 years

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19
Q

What calculators are used to measure fracture risk in osteoporosis?

A

FRAX or Qfracture

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20
Q

The new SIGN guideline is no longer based on treating patients in terms of their mineral bone density. What is it more concerned about?

A

Fracture Risk

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21
Q

Give an example of a risk factor for a fragility fracture that is non-modifiable

A
  • Age
  • Gender
  • Ethnicity
  • Previous #
  • FHx
  • Menopause ≤ 45 years
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22
Q

What risk factors for fragility fractures are modifiable?

A
  • BMD
  • Alcohol
  • Weight/Physical inactivity
  • Smoking
  • Drugs (e.g. steroids)
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23
Q

What biochemical investigations should be considered in a patient who you are suspecting has osteoporosis

A

U+Es
LFTs
FBC and Plasma Viscosity
TSH

Consider:

  • Coeliac antibodies
  • 25OH Vitamin D
  • Parathyroid hormone
24
Q

What endocrine conditions are secondary causes of osteoporosis?

A

hyperthyroidism
hyperparathyroidism
Cushing’s disease

25
What GI conditions cause secondary osteoporosis?
coeliac disease IBD chronic liver disease chronic pancreatitis
26
What respiratory conditions are linked to the development of secondary osteoporosis?
CF | COPD
27
What lifestyle advice is used in management of osteoporosis?
- High intensity strength training - Low-impact weight-bearing exercise - Avoidance of excess alcohol/smoking - Fall prevention
28
How much calcium should post-menopausal women aim to eat per day in order to reduce their fracture risk?
1000 mg calcium (3-4 portion calcium rich foods)
29
What non-dairy foods are considered sources of calcium?
Non-dairy sources include - bread and cereals (fortified) - fish with bones, nuts, - green vegetables, beans
30
What drug treatments are often given in osteoporosis?
- Calcium & Vit D supplements - Bisphosphonates - Denosumab (monoclonal antibody) - Teriparatide (Parathyroid hormone anabolic agent) - HRT - SERMS (Selective Estrogen Receptor Modulators) - Testosterone
31
How far apart should patients be taking their oral bisphosphonates and their calcium supplements?
Calcium supplements should not be taken within 2 hours of oral bisphosphonates
32
Give examples of Bisphosphonates
alendronate | risedronate
33
How do bisphosphonates work?
They are ingested by osteoclasts cause cell death => restoring Osteoclast:osteoblast ratio
34
How long should patients remain on bisphosphonates?
benefit for 5 years (10 y if vertebral fracture) | Patients may also benefit from a period of no bisphosphonates
35
What complications may present if patients remain on Bisphosphonates long term?
osteonecrosis of the jaw oesophageal Ca atypical fractures
36
How is Zoledronic Acid administered?
- Once yearly IV infusion for 3 years - 5 mg in 100 ml NaCl over 15 mins * *can cause acute phase reaction on first infusion**
37
How does Denosumab work?
Monoclonal Antibody inhibits development and activty of osteoclasts => prevents bone resorption
38
How is Denosumab administered?
Subcutaneous injection 6 monthly
39
What are the adverse effects of Denosumab?
Hypocalcaemia eczema cellulitis
40
Teriparatide mainly aims to stimulate bone growth rather than reduce bone loss. TRUE/FALSE?
TRUE
41
Describe the direct and indirect effects of corticosteroids on bone
DIRECT: - Reduce osteoblast activity and lifespan - Suppress replication of osteoblast precursors - Reduce Ca absorption INDIRECT: - Inhibit gonadal and adrenal steroid production
42
What areas of the body do glucocorticoids act upon?
Bone Kidney Gut Pituitary
43
Describe the activity of both osteoclasts and osteoblasts in Paget's disease
Abnormal osteoclastic activity | increased osteoblastic activity
44
Describe the structure of bone developed in Paget's disease
Abnormal bone structure with reduced strength and increased fracture risk
45
Can Paget's disease present in more than one site?
Yes - single site (monostotic) - multiple sites (polyostotic)
46
What areas of bone are most affected by Paget's disease?
long bones pelvis lumbar spine skull
47
How does Paget's disease usually present?
bone pain deformity deafness compression neuropathies
48
What condition is a rare complication of Paget's disease?
Osteosarcoma
49
What scan can be used to show the distribution of Paget's disease?
isotope bone scan
50
If the pain in Paget's disease does not respond to analgesia, what medication can be used?
Bisphosphonates
51
What complications can patient's develop in Paget's disease?
Bowing of femur/tibia Deaf if skull involvement curved spine
52
What genes are associated with the development of Paget's disease and what do the encode?
mutations of type 1 collagen genes COL1A1 COL1A2
53
How is Paget's disease inherited?
Autosomal Dominant Inheritance
54
What other clinical signs are noted in severe forms of Osteogensis Imperfecta?
blue sclerae | dentinogenesis imperfecta
55
Describe the difference in age of presentation of mild to severs osteogenesis imperfecta
Mild - May not present until adulthood Severe - usually present in childhood due to fractures having already occurred
56
What treatments are used in Osteogenesis Imperfecta?
- fracture fixation - surgery to correct deformities - bisphosphonates
57
What differential diagnosis should always be considered in a child presenting with a fracture that you think may be OI?
Non-accidental Injury

Endocrine (24 decks)

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