Fracture biomechanics and classification

Question 1

What are the forces that must be neutralized for a fracture to heal?

Answer 1

1. bending
2. torsion
3. compression
4. tensino

Question 2

What determines what forces predominate at a fracture site?

Answer 2

1. geometry of fracture

2. location of muscle groups

Question 3

Compression is good for what type of fracture and bad for what other type of fracture?

Answer 3

1. good for transverse fracture to reduce motion

2. bad for oblique fracture because fragments shear past

Question 4

How are fractures classified?

Answer 4

1. extent of soft tissue
2. degree of cortical disruption
3. geometry
4. location in bone
5. degree and direction of displacement

Question 5

What does bending cause?

Answer 5

agnulation

Question 6

What happens to the bone with bending?

Answer 6

1. one side is being compressed (concave) and one side is has tension (convex)

Question 7

Where is the neutral axis of a bone?

Answer 7

usually in the centre of the medullary canal and is where there is neither tension nor compression

Question 8

What happens if you fix a bone with something that runs down the neutral axis?

Answer 8

the apparatus will be subjected to less bending force than something running down the outside of the bone

Question 9

What does torsion cause?

Answer 9

rotation

Question 10

What is torsion

Answer 10

the tendency for a bone or its pieces to twist around long axis

Question 11

Where does compressino act?

Answer 11

along the long axis of bone and moves ends of bone twoard eachother

Question 12

What happens if compression is applied to an oblique fracture?

Answer 12

there is overriding–>shear

Question 13

What does tension cause?

Answer 13

distraction/avulsion fractures of apophyses (olecranon and calcaneus)

Question 14

What control do casts and splints provide?

Answer 14

1. bending

2. ok torsion

Question 15

What control do wires provide

Answer 15

1. good tension

no others

Question 16

What control do intramedullary pins provide?

Answer 16

1. good bending

no others

Question 17

What control do interlocking nails provide

Answer 17

1. bending
2. tension
3. torsion
4. compression

Question 18

What control do external skeletal fixation provide?

Answer 18

1. bending
2. tension–but rare use for this
3. torsion
4. compression

Question 19

What control do bone plates provide?

Answer 19

good control of all but

weakest in combined compression and bending

Question 20

What control do bone plates provide?

Answer 20

good control of all but

weakest in combined compression and bending

Question 21

When does a bone fracture?

Answer 21

when the magnitude of the force placed upon it at a specific site exceeds its ability to resist the force without deforming permanently

Question 22

What is a closed fracture?

Answer 22

no wound connecting bone to outside world

Question 23

What is an open fracture

Answer 23

there is a connection with open world

Question 24

What is a greenstick gracture

Answer 24

bending or folding fracture. the cortex doesn’t actually break all the way through but bones deforms

Question 25

What is a fissure?

Answer 25

it is a crack and only involves one cortex and is usually longitudinally oriented

Question 26

What is a saucer?

Answer 26

a divot that gets taken out of one cortex (e.g. horse 3rd metacarpal)

Question 27

what is a complete fracture?

Answer 27

both cortices are disrupted

Question 28

What is a depression

Answer 28

e.g. in skull

Question 29

What is a transverse fracture?

Answer 29

A fracture perpendicular to long axis of bone | Torsion is a big problem, compression good

Question 30

What is an oblique fracture?

Answer 30

short or long.

Question 31

What are the two types of oblique fracutre?

Answer 31

short and long (long is more than twice the diameer of the bone

Question 32

What is a big problem with oblique fractures?

Answer 32

shearing

Question 33

What is a spiral fracture

Answer 33

a spiral, shearing also a problem

Question 34

What are types of comminuted fractures?

Answer 34

1. butterfly 2. highly comminuted 3. segmental 4. multiple fracture

Question 35

What two things determine if a fracture is simple or highly comminuted?

Answer 35

1. the magnitude of the force and the speed of the force

Question 36

What does it mean that bone is a viscoelastic force?

Answer 36

it means that its deformation properties depend on loading rate

Question 37

Distinguish bone breaking between slow and fast application of force?

Answer 37

1. slow application: less force before bone bends and breaks 2. fast application: more energy absorbed, but more energy so shatters--more concomitant soft tissue damage (high energy)

Question 38

Where can fractures be located?

Answer 38

1. articular 2. physeal 3. metaphyseal 4. diaphyseal (proximal, middle or distal third) 5. condylar/suparcondylar/subtronchanteric

Question 39

Where can fractures be located?

Answer 39

1. articular 2. physeal 3. metaphyseal 4. diaphyseal (proximal, middle or distal third) 5. condylar/suparcondylar/subtronchanteric

Question 40

What are to ways you can describe displacement with regard to fracture?

Answer 40

1. displaced | 2. non-displaced--suggests intact periosteal sleeve

Question 41

How do you describe displacement?

Answer 41

by referring to the distal fragment location relative to proximal

Question 42

How can you describe the angle made by fragments?

Answer 42

describe what way the vertex of the angle is pointing

Question 43

What are 4 causes of fracture?

Answer 43

1. traumatic 2. pathologic 3. fatigue 4. iatrogenic

Question 44

why do we care about fracture classification?

Answer 44

1. strong influence on how will heal