lec 8 - bone injuries

Question 1

function of bone

Answer 1

• protects bone
• provides body with shape
• faciliates mvmt
• provides framework for support

Question 2

what are the types of bone and example of where they occur

Answer 2

long - femur
flat - sternum
irregular - vertebrae
short - wrist bones (carpals)

Question 3

what are the three rules for bone adaptation

Answer 3

1. dynamic loading
2. short duration loading
   - (extended loading durations have diminishing adaptive returns)
3. irregular loading required
   - (bone cells accomodate to regular loading making them less responsive)

Question 4

what are the 3 fracture classifications

Answer 4

traumatic fracture
pathologic fracture
fatigue fracture

Question 5

what causes a traumatic fracture

Answer 5

acute high energy trauma

Question 6

what causes a pathologic fracture

Answer 6

minimal trauma in a weak, diseased, or fragile bone

Question 7

what causes a fatigue fracture

Answer 7

accumulation of microtrauma assocaited with repetitive loads (stress fracture)

Question 8

what is the difference between a open and closed fracture

Answer 8

closed = bone doesn’t break through skin
open = bone breaks through skin (high risk of infection)

Question 9

what are the 8 types of fracture patterns

Answer 9

transverse
linear
oblique non displaced
oblique displaced
spiral
greenstick
comminuted
butterfly

Question 10

what is the cause of a transverse fracture

Answer 10

tension

Question 11

what is the cause of an oblique fracture

Answer 11

compression

Question 12

what is the cause of a butterfly fracture

Answer 12

bending
(part under compression and part under tension)

Question 13

what is the cause of a spiral fracture

Answer 13

torsion

Question 14

what is the difference between fluctuating loads and monotonic loads

Answer 14

fluctuating loads are more detrimental than monotonic loads
- cause accumulation of microtrauma

Question 15

what are the three stages of healing in bone fractures

Answer 15

1. inflammatory
2. reparative
3. remodelling

Question 16

what occurs during the inflammatory stage of healing

Answer 16

• immobilises fractured bone and activates cells for repair
• hematoma formation
• vasodilation
• serum exudation
• infiltration of inflammatory cells

Question 17

what happens during the soft callus phase of reparative healing

Answer 17

• replaces blood clot from inflammation phase
• inflammation triggers cell division and growth of new blood vessels
• chondrocytes excrete collagen and PGs to form fibrocartilage

Question 18

what occurs during the hard callus phase of reparative healing

Answer 18

• endochondral ossification
• bone formation by osteoblasts
• soft callus turns to hard callus made of woven bone

Question 19

what occurs during the remodelling phase of healing

Answer 19

• gradually restores original shape and internal structure
• woven bone replaced by secondary bone
• longest phase

Question 20

how long does each phase of fracture healing take

Answer 20

inflammatory = 3-7 days
reparative = 2 weeks for each callus phase
remodelling = can take years

Question 21

what is involved in conservative treatment of fractures

Answer 21

splinting, bracing, casting, bandages, orthoses

Question 22

what is the difference between internal and external fixation

Answer 22

internal = plates and screws inside bone and inside skin
external = attachments to bone that exit the skin and attach to cage to immobilise the fracture