KCP: Fractures & Osteoporosis

Question 1

How does bone repair itself?

Answer 1

With a little damage you get osteoclasts which clean it up, these die off then the osteoblast build and repair it

Question 2

What cause an increased risk of fracture in older people?

Answer 2

• Osteoporosis
• Loss of muscle mass
• Neurological impairment
• Arthritis
• Medications
• Environment and isolation

Question 3

What is osteoporosis

Answer 3

It is a disease charaterised by low bone mass and micro-architectural deterioration of bone tissue.

Specifically if the bone density is >2.5 standard deviations from the average of a 30 y/o.

Caused by over active/ too many osteoclasts and not enough osteoblasts

Question 4

How do you diagnose osteoporosis

Answer 4

Use a DEXA scan

Question 5

What is a DEXA scan?

Answer 5

A DEXA scan (duel energy x-ray absorptiometry) uses two x-rays with different energy peaks, one is absorbed more by soft tissues and one absorbed more by bone. The soft tissue absorbtion is then substracted from the bone reading to get the bone mineral density

Question 6

4 reasons you might get a DEXA scan?

Answer 6

• Fragility fracture aged >50
• Suspected vertebral fracture
• Taking oral glucocorticoids
• The ten year fracture risk is >10%

Question 7

5 treatments for osteoporosis

Answer 7

• Ensure adequate calcium and vitimin D intake
• Regular exercise
• Bisphosphonates (targets bone surface, prevents resorption, increases mineralisation, increases bone density)
• Anabolic drugs (builds new bone)
• Oestrogen (now rarely used due to adverse effects)

Question 8

Bisphosphonate mechanism of action

Answer 8

Bosphosphonates adher to bone surface, these are consumed by osteoclasts which then cause the osteoclasts to die

Question 9

Osteocytes

Answer 9

Maintains bone tissue and make up >90% of bone

Question 10

Osteoblasts

Answer 10

Build new bone, live at bone surface

Question 11

Osteogenic cell

Answer 11

Pre cursor to osteocytes and osteoblasts

Question 12

Osteoclast

Answer 12

Degrade bone thats not needed

Question 13

T-score

Answer 13

Bone density compared to the average of a 30 y/o of the same sex

Question 14

Z-score

Answer 14

Bone density compared to the average of somoene the same age and same sex

Question 15

Fill out this chart with either up arrows or down arrows

Answer 15

PTH doesn’t directly increase gastro intestinal absorption of calcium but an important effect of PTH on the kidney is its stimulation of the conversion of 25-hydroxy vitamin D into 1,25-dihydroxy vitamin D (calcitriol) which does increase GIT absorption of calcium

Additional vit d doesn’t directly increase bone mineralisation however by ecouraging more ca2+ in the blood this will stimulate calcitonin which will encourage bone mineralisation

Question 16

Adverse effects of bisphosphonates orally and IV and generally

Answer 16

Orally:

• Oesophagus inflammation
• Indigestion
• Patients must fast before taking them orally

IV:

• Intravenous bisphosphonates can cause flu like symptoms
• Osteonecrosis of the jaw
• Renal impairment

Generally:

• Atypical femoral fractures due to bone remodelling?

Question 17

Oestrogen treatment adverse effects

Answer 17

Question 18

What is renal osteodystrophy?

Diagnoses and treatment?

Answer 18

This is a decrease renal vitamin d activation resulting in an increase in PTH

Can identify it by increased level of PTH

Treated with already activated vitamin d