Final Exam - Intro To Fractures Part I

Question 1

what are the goals for a patient presenting with a fractured limb?

Answer 1

1. preserve life
2. preserve limb (spine/pelvis)
3. prevent infection
4. promote full return of function

Question 2

what are your goals for a fractured limb?

Answer 2

1. restore anatomy
2. establish stability
3. preserve blood supply
4. early mobilization of limb & patient

Question 3

what questions should you ask yourself prior to working on a patient with a fracture?

Answer 3

1. is the limb viable?
2. do I have the experience?
3. do I have the equipment?
4. is the owner committed?
5. what is best for the patient?

Question 4

why are biomechanics important in fracture repair?

Answer 4

1. you can figure out the types of forces that caused it to estimate healing potential & time frame
2. decide the best way to counteract forces acting on the fracture to repair it
3. choose the best implant based on estimated damage involved

Question 5

what special material properties make up bone? what do they do?

Answer 5

hydroxyapatite - brittle but strong

collagen - stretchy & supportive

bone is 2/3 mineral (strength in compression) & 1/3 collagen (strength in tension & flexibility)

Question 6

what happens if you have demineralized bone?

Answer 6

bendy bone

Question 7

what happens if you have deproteinized bone?

Answer 7

bones that easily break

Question 8

what are the material properties of bone? what are they independent of?

Answer 8

stress - measure of internal forces
strain - measure of subsequent deformation

material properties are size & shape independent

Question 9

what are the structural properties of bone? what are they dependent on?

Answer 9

load - measure of applied or internal forces
deformation - subsequent change in shape or length

structural properties are size & shape dependent

Question 10

why is it important to consider the material properties of a surgical implant & fractured bone?

Answer 10

in order to choose the correct implant, you need to know both - use the force-deformation or stress/strain curve

Question 11

T/F: it takes a lot of force to fracture a bone in pure bending

Answer 11

true

Question 12

what is viscoelastic in terms of special properties of bone?

Answer 12

strength properties depend on the rate of applied strain

Question 13

what is anisotropic in terms of special properties of bone?

Answer 13

direction of load is important

Question 14

T/F: it takes relatively little force to fracture a long bone in torsion

Answer 14

true

Question 15

how are fracture location & displacement described?

Answer 15

distal segment is described relative to the proximal segment

Question 16

what is an example of an incomplete fracture?

Answer 16

greenstick fracture - common in young animals

Question 17

what is an open fracture?

Answer 17

bone communicates with the outside environment

Question 18

what are the grades of open fractures?

Answer 18

grade 1: bone breaks skin from inside out

grade 2: small wound <1cm from external force

grade 3: large wound from external force

Question 19

what are the different types of salter-harris fractures?

Answer 19

type I: straight through the physis

type II: physis & metaphysis

type III: physis & epiphysis (articular)

type IV: metaphysis, physis, epiphysis (articular)

type V: crush injury to physis

Question 20

what components should be included in a fracture description?

Answer 20

1. incomplete vs complete
2. closed vs open
3. anatomic location
4. displacement
5. etiology - intrinsic vs extrinsic

Question 21

when looking at fracture kinetics, how does amount of energy affect the fracture?

Answer 21

low energy = better energy absorption, simple fracture

higher energy = very comminuted fractures