Bone Growth and Fractures

Question 1

what is the role of sex steroids in bone growth?

Answer 1

stimulate bone growth spurt but promote close of epiphyseal plates

Question 2

what happens to bone growth at end of puberty?

Answer 2

• growth in length ceases
• cell proliferation slows and plate thins
• plate invaded by blood vessels
• epiphyseal and diaphyseal vessels unite
• may leave visible line on x-rays

Question 3

which bones have only one ossification centre?

Answer 3

• carpals
• tarsals
• ear ossicles

Question 4

which bones have 2+ ossification centres?

Answer 4

head of humerus has 3

Question 5

what are the zones of the epiphyseal plate?

Answer 5

• ossification (osteogenic)
• calcification
• hypertrophic
• growth (proliferation)
• resting zone

Question 6

what is the function of the resting zone?

Answer 6

matrix production

Question 7

what is the function of the growth zone?

Answer 7

cell proliferation

Question 8

what is the function of the hypertrophic zone?

Answer 8

calcification of matrix

Question 9

what is the function of the metaphysis zone?

Answer 9

• bone formation

- vascularisation

Question 10

what are examples of diseases due to defects in resting zone?

Answer 10

diastrophic dwarfism:

- defective collagen synthesis/processing of proteoglycans

Question 11

what are examples of diseases due to defects in growth zone?

Answer 11

achondroplasia; malnutrition; irradiation injury:
- deficiency in cell proliferation and/or matrix synthesis

gigantism:
- increased cell proliferation

Question 12

what are examples of diseases due to defects in hypertrophic zone?

Answer 12

rickets; osteomalacia:

- insufficiency of calcium or phosphate for normal calcification

Question 13

what are examples of diseases due to defects in metaphysis zone?

Answer 13

osteomyelitis:
- bacterial infection

osteogenesis imperfecta:
- abnormality

scurvy:
- inadequate collagen turnover

Question 14

what are the requirements of normal growth and bone development?

Answer 14

• calcium
• phosphorus
• vitamin A, C, D
• balance between growth hormone, thyroid/parathyroid, oestrogen/androgens

Question 15

what is the ratio of cortical/compact bone to cancellous/trabecular bone?

Answer 15

8:2

Question 16

what is the location of cortical/compact bone?

Answer 16

shaft of long bones

Question 17

what is the location of cancellous/trabecular bone?

Answer 17

• ends of long bones
• vertical bodies
• flat bones

Question 18

what is the structure of cortical/compact bone?

Answer 18

concentrically arranged lamellae - haversian systems

Question 19

what is the structure of cancellous/trabecular bone?

Answer 19

meshwork of trabeculae with intercommunicating spaces

Question 20

what is the function of cortical/compact bone?

Answer 20

mechanically strong

Question 21

what is the function of cancellous/trabecular bone?

Answer 21

metabolic

Question 22

what is turnover like in cortical/compact bone?

Answer 22

slow

Question 23

what is the turnover like in cancellous/trabecular bone?

Answer 23

fast

Question 24

what is the periosteum like in cortical/compact bone?

Answer 24

thick

Question 25

what is the periosteum like in cancellous/trabecular bone?

Answer 25

thin

Question 26

what is blood supply like in cortical/compact bone?

Answer 26

slow

Question 27

what is blood supply like in cancellous/trabecular bone?

Answer 27

rich

Question 28

what is the fracture pattern of cortical/compact bone?

Answer 28

direct or indirect violence may result in deficits at the fracture site leading to non-union

Question 29

what is the fracture pattern of cancellous/trabecular bone?

Answer 29

honeycomb structure fails as the result of compression ( e.g. fall from height compacts bone)

Question 30

what information does x-ray imaging provide?

Answer 30

- site and bones involved - clues on soft tissue injury - clues on energy transfer e.g wide displacement, comminuted, multiple fracture sites

Question 31

what is a fracture?

Answer 31

a complete or incomplete break in a bone

Question 32

what ways are there to describe a fracture?

Answer 32

- site - open to surface - contaminated - associated soft tissue injury - joint involvement - number of pieces - alignment - degree of separation

Question 33

what are some types of fracture patterns?

Answer 33

- transverse - linear - oblique non-displaced - oblique displaced - spiral - greenstick - comminuted

Question 34

avulsion fracture

Answer 34

a fragment of bone is separated from main mass

Question 35

buckle fracture

Answer 35

- a.k.a impacted fractur, torus fracture - ends are driven into each other - commonly seen in arm fracture in children

Question 36

compression or wedge fracture

Answer 36

usually involves vertebrae

Question 37

pathological fracture

Answer 37

caused by a disease that weakens the bones

Question 38

stress fracture

Answer 38

a hairline crack

Question 39

what types of fracture are limb threatening/non-union risk?

Answer 39

- dislocation - comminuted - compound - compartment syndrome - vascular/nerve injury - significant soft tissue injury - pathological bone

Question 40

what are the 3 major phases of fracture healing?

Answer 40

1. reactive phase 2. reparative phase 3. remodelling phase

Question 41

what is involved in the reactive phase of fracture healing?

Answer 41

- fracture and inflammatory phase (haematoma) | - fibroblasts in periosteum proliferate to form granulation tissue around fracture site

Question 42

what is involved in the reparative phase of fracture healing?

Answer 42

- callus formation: osteoblasts quickly form woven bone to bridge gap - woven bone is weak as collagen fibres arranged irregularly - lamellar bone laid down, collagen organised in regular sheets to give strength and resilience

Question 43

what is involved in the remodelling phase of fracture healing?

Answer 43

remodelling by osteoclasts to restore original bone shape

Question 44

when are conservative forms of fracture treatment used?

Answer 44

simple fracture with low risk of non-union: - dependent on natural healing process - +/- immobilisation - rehabilitation

Question 45

when are forms of intervention treatment used for fractures?

Answer 45

fractures with limb threat or risk on non-union: - augment natural healing with replacement of strengthening - +/- immobilisation - rehabilitation