Fractures through the ages

Question 1

describe how bone formation changes in utero –> early years

Answer 1

in utero

• there is increase bone formation
  because: calcium needed for development

then as you develop
- decrease in amount of trabecular tissue
change in trabecular architecture

Question 2

What is osteopososis

Answer 2

osteoporosis

• loss of bone density , bone mass,
• causes fractures

Question 3

What can detect osteoporosis?

Answer 3

DEXA Scan

Question 4

What are risk factors for osteoporosis

Answer 4

• old
• smoker
• drinker
• family history
• post menopausal

Question 5

Describe the bone composition

Answer 5

• most bone = matrix (90%) —>
  a) inorganic (calcium + phosphorous - hydroxy apatite)
  b) organic (collagen type 1)
• 10% (living cells)
• osteoprogenitor cells, osteoclast, osteoblast, osteocytes

Question 6

Describe the process of normal bone turnover

Answer 6

Resting –> resorption –> reversal –> formation –> resting –> resorption

1 . osteoclasts digest bone within a sealed resorption vacuole

2. preosteoblasts form in digested area
3. there is new formation and maturation of osteoblasts
   –> which builds up osteoid tissue
   (cause mineralisation)
4. bone returns to normal state

Question 7

oestogen in the body is responsible for _______ in the bone

what is the consequence of depletion of oestrogen e.g post menopause

Answer 7

osteoclastic cell apoptosis

post menopause

• resorption is&raquo_space; formation
• loss of boen mass
• dec in bone mass + structure

Question 8

what treatments are used to reduce osteoporosis?

how do they work?

Answer 8

1. Bisphosphonates

2. Denusumab

Question 9

What are some SE of bisphosphonates ?

Answer 9

• suppression of osteoclatic activity –> and thus osteoblastic activity

–> bone becomes more fragile –> can cause fatigue fracture

Question 10

how do bisphosphontes work?

Answer 10

• prevents osteoclasts from resorbing bone
• -> no longer able to secrete enzyme which dissolves bone
• action lasts very long e.g 10 years

Question 11

How do denusumabs work?

Answer 11

• affects remodeling process by trying to stop excessive resorption of bone
• Denusumab binds to RANKL pathway
• -> bone resorption is inhibited
• action is very short
• -> give in short bursts

Question 12

hip fracture
within 30 days = 10% mortality
–> great loss in morbidity

Answer 12

-

Question 13

fracture healing

Answer 13

surgically:
- fracture occurs –> alignment of bones (using screws)
- osteoblast –> build up bone and healing of bone

naturally:
- requires vascularity
- requires mechanical stability of fracture
e. g rods, plate + screws

Question 14

NOTE
in earlier life –> you build up bone mass

in later life –> less susceptibility to fracture

• in adolescence –> people need to exercise –> build up bone

Answer 14

-

Question 15

3 main functions of calcium

Answer 15

calcium is important in:

• nerve function
• muscle function
• blood clotting

Question 16

sources of Vit D in food

Answer 16

• oily fish

Question 17

waht is callus formation

Answer 17

• can occur if patient is in cast

4 stages:

1. haematoma formation + inflammation occurs
   - -> progenitor cells invade
2. soft callus forms
3. hard callus forms (cartilage –> ossifies into disorganised woven bone)
4. remodeling occurs (woven bone –> lamellar bone)

Question 18

NOTE: rate of bone remodelling is higher in younger people

Answer 18

-

Question 19

describe the different fracture patterns,

and what can cause each type

Answer 19

• spiral type fracture
• -> twisting injury
• oblique fracture
• -> direct compression
• butterfly fragment
• -> due to bending force
• high energy injury
• -> e.g hit by car bumper
• transverse fracture
• -> due to tension
• -> muscles pulls it apart
• greenstick fracture
• -> one side of the bone is broken
• -> other side = only bent.

Question 20

What is an Osteoprotegerin?

Answer 20

Osteoprotegerin = produced by osteoblasts

–> important regulator in osteoclast development and function.