Bone growth and fracture healing

Question 1

How does bone grow

Answer 1

hyaline cartilage model (long bone)
primary ossification centre - grow
- SOC - at each end
- medullary cavity
- epiphyseal plate

Question 2

Long bone anatomy

Answer 2

multiple growth plates

Question 3

growth plate at knew provides

Answer 3

greatest length at development

Question 4

What is the metaphysiis

Answer 4

flare at the end

Question 5

What is the diaphysis

Answer 5

the shaft

Question 6

What is the Epiphysis

Answer 6

On joint side of physis

Question 7

Cortical bone is a

it is predominantly ?

Answer 7

impact structure
circular lamellae - blood vessels

diaphysis
resists - bending and torsion

Question 8

Cancellous bone is a

Answer 8

Shock absorber

mainly metaphysisis

Question 9

What is a fracture

Answer 9

break in structural continuity of bone

crack, break, split , crumpling

Question 10

Why do bones fail?

Answer 10

High energy transfer - takes a lot to break

• repetitive stress in normal bones - stress fracture

Question 11

older people have/ other bone conditions that can cause fracture

Answer 11

low energy transfer in abnormal bones

osteoporosis
osteomalacia, metastatic tumour

Question 12

Fracture biology is (2)

what process is it?

Answer 12

• mechanical and structural failure of bone
• disruption of blood supply

regernative process (no scar) (4 stages)

Question 13

What is stage 1 and when does it occur

what cells come?

Answer 13

INFLAMMATION

immediately after fracture - hepatoma and fibrin clot released

platelets , neutrophils, macrophages, lysosomal enzymes

Question 14

What repair cells come in? (2 - explain)

Answer 14

fibroblasts

mesenchymal and osteoprogenitor cells - (cells in muscle and soft tissue) (cells from the canal) - fibro and osteoblasts

Angiogenesis

• low oxygen gradient in centre of fracture
• macrophages produce angiogenic factors under hypoxic conditions

Question 15

How might doctors affect inflammation?

Answer 15

NSAIDS
loss of hepatoma - open fracture or surgery

extensive tissue damage - poor blood supply

Question 16

Platelet concentrates ? what do they release (4)

Answer 16

“Buffy coat”

Platelet derived growth factor (PDGF)
TGFB)

insulin growth factors
VEGF

Question 17

What is stage 2

Answer 17

soft callus

Question 18

When does soft callus begin and when does it last until?

what is there a continued increase in?

Answer 18

when pain and swelling subsides

bony fragments are united by cartilage or fibrous tissue

• vascularity

Question 19

soft callus - how can we affect it?

Answer 19

• replace cartilage (DMB)

- Jump straight to bone (bone graft and substitutes)

Question 20

What is an autogenous cancellous bone graft

Answer 20

gold standard

• osteoconductive
• osteoinductive

Question 21

what happens in stage 3?

In a typical long bone fracture what bone formation is there?

Answer 21

hard callus
conversion of cartilage to woven bone

Endochondrial
Membranous

Question 22

What is increasing in stage 3

Answer 22

rigidity

Obvious callus

Question 23

What happens in stage 4 bone remodelling ?

Answer 23

Conversion of woven bone to lamellar bone

Question 24

What is reconstituted in stage 4?

Answer 24

medullary

Question 25

What is critical for the progression of fracture healing

Answer 25

Mechanical proporties of tissue and their environment

Question 26

What is strain

Answer 26

Degree of instability

Question 27

If strain is low what happens?

Answer 27

induction of tissue differentiation fails

too high and healing process does not progress to bone formation

Question 28

Delayed union is?

Answer 28

failure to heal in expected time

Question 29

What is non-union (6)

Answer 29

• failure to heal
• failure calcification fibrocartilage
• abundant callus formation
• pain and tenderness
  sclerosis