Fractures Through the Ages - 09.03.2020

Question 1

Bone composition

Answer 1

a) cells
- OC (macrophage like)
- OB
- osteocyte
- osteoprogenitor

b) matrix
- Organic (collagen, mucopolysaccharides, non-collagenous proteins)
- Inorganic (calcium and phosphate -> hydroxyapatite)

Question 2

Normal bone turnover

Answer 2

• constant
• reason for that: otherwise you would get stress cracks that could lead to fractures
• monitored mainly by osteocytes but also osteoblasts.
• 5% bone turns over every year
• osteoporosis is when there is more breakdown than production.

Question 3

DEXA scan scores

Answer 3

T-score: compares your bone mass in those areas in someone of the same gender, ethnicity and height at their peak bone age (25) and looks at how many SDs away from that you are.

Z-score

Question 4

Bisphosphonates

Answer 4

• kill osteoclasts
• half life around 7 years
• strops remodelling which is a problem: they can get micro cracks and fractures

Question 5

Risk groups for osteoporosis

Answer 5

• postmenopausal women

- amputees

Question 6

Problem with telling people about their bone weakness

Answer 6

People are scared that they cannot exercise because they have ‘‘crumbly bones’’

however exercise would aid in strengthening bones

Question 7

Atypical fractures

Answer 7

• abnormal sites, under abnormal conditions (e.g. not necessarily excessive stress)
• may be due to bisphosphonate treatment

Question 8

Denosumab

Answer 8

• alternative to bisphosphonates
• denosumab binds to RANKL and prevents interaction with RANK
• shorter half life
• specifically targets osteoclasts
• very expensive (health economics drive a lot of choices)

Question 9

Hip Fracture

Answer 9

• 10% dead 30d post fractures
• 30% people are dead within a year (not necessarily due to the fracture but those are the stats)
• quite frequently seen in elderly
• fragility fracture

Question 10

Wolff’s law

Answer 10

Bone remodels according to the stresses applied to it

Question 11

What improves the strength of bone?

Answer 11

• diet (calcium in childhood should be high to reduce the risk of OP later, also people with OP are encouraged to have calcium)
• vitamin D
• exrecise (more deep flexure needed to promote strength of bones in the hip area)

Question 12

Fracture healing by calls formation

Answer 12

1. haematoma (or inflammation) in week 1
2. soft callus (week 2-3)
3. Hard callus (weeks 4-16); woven bone; at this point you can start using the broken bown.
4. Remodelling (week 17 and beyond) -> Wolff’s law: the parts of bone are reinforced, the not used bone is removed.

Other way: surgery to put bins together.

Question 13

How long does it take for a bone to be functional after a fracture?

Answer 13

around 6w

however, at that point it does not have the same strength and load bearing capacity yet

Question 14

Fracture patterns

Answer 14

• spiral fracture
• oblique fracture (usually compression)
• butterfly fragment (usually due to direct hit)
• transverse fracture
• greenstick fracture (seen in paediatrics; breaks on one side, stays intact in the other; they have a thick periosteum)