Lecture 25 - Fracture Mechanics

Question 1

What is a Type I Salter fracture?

Answer 1

Straight across

Question 2

What is a Type II Salter fracture?

Answer 2

Above

Question 3

What is a Type III Salter fracture?

Answer 3

Lower or beLow

Question 4

What is a Type IV Salter fracture?

Answer 4

Two

OR

Through

Question 5

What is a Type V Salter fracture?

Answer 5

ERasure of the growth plate

OR

cRush

Question 6

What are the 5 components used to describe a fracture?

Answer 6

1. Open or Closed
2. Configuration (transverse, short oblique, long onlique, comminuted)
3. Location of the fracture within the bone
4. Specific bone fractured
5. Displacement and overriding

Question 7

What are the types of implants (materials) used in fracture repair?

Answer 7

316 LVM Stainless Steel

Titanium Pure

Question 8

Stiffness of a rod is _____.

Answer 8

radius to 4th power

Question 9

Stiffness of a square beam is _____.

Answer 9

height to 3rd power

width to 1st power

Question 10

Stiffness of a length of with beam is _____.

Answer 10

length to 3rd power

Question 11

To use cerclage wire, fracture must be _____.

Answer 11

Long oblique

Question 12

T/F: Cerclage wire can be used as the sole means of repair.

Answer 12

False

Question 13

What size cerclage wire should be used in dogs vs. cats/toy breeds?

Answer 13

Dogs = 1-1.2mm (18-20G)

Cats/toy breeds = 0.64-0.81mm (20-22G)

Question 14

___ or more circumferential cerclage wires must be used, placed _____ apart.

Answer 14

2, 8-10mm

Question 15

Cerclage should be no closer than ____ from the fracture ends.

Answer 15

5mm

Question 16

Cerclage wire must reside directly on _____ and confirmed to be _____.

Answer 16

bone, tight

Question 17

The size of the intramedulary pin should be ___% the diameter of the _____ cavity.

Answer 17

50-75%, medullary

Question 18

The intramedulary pin should be placed _____ when possible.

Answer 18

normograde

Question 19

The intramedulary pin should be seated in the _____.

Answer 19

trans (far) epiphysis

Question 20

The fixation construct of the intramedulary pin should counter _____, or _____ should be employed.

Answer 20

torsional stress, ancillary devices

Question 21

If intramedulary pins are used in conjunction with plates, the size of the pin should be ____% the diameter of the _____.

Answer 21

30-50%, medullary cavity

Question 22

The size of the dynamic compression plate used is dictated by the size of the _____ allowed.

Answer 22

screw

Question 23

The major diameter of the screw used should approach but be no greater than ___% of the diameter of the bone being plated with a dynamic compression plate.

Answer 23

20%

Question 24

Screws should engage at least ____ cortices on either side of a fracture when using a dynamic compression plate.

Answer 24

6

Question 25

Screws shoud engage both _____ and _____ cortices when using a dynamic compression plate.

Answer 25

cis (near), trans (far)

Question 26

When plating with a dynamic compression plate, the fracture should be _____ so that there is cortical-cortical contact (esp on the _____ cortex).

Answer 26

reduced, trans

Question 27

The dynamic compression plate should be _____ so that it lies directly on the bone.

Answer 27

contoured

Question 28

In dynamic compression plating, screws should be placed in _____ --- away from the fracture line in the \_\_\_\_\_.

Answer 28

"load position", dynamic compression hole

Question 29

The size of the locking plate is dictated by the size of the _____ allowed.

Answer 29

screw

Question 30

With a locking plate, the major diameter of the screw should approach, but be no greater than \_\_\_% of the diameter of the bone being plated.

Answer 30

20%

Question 31

How many screws should engage bone on either side of a fracture when using a locking plate?

Answer 31

3-4

Question 32

What type of screw can be used with a locking plate?

Answer 32

unicortical

Question 33

When using a locking plate, it must not \_\_\_\_\_, but should be as _____ as possible.

Answer 33

lay directly on the bone, close

Question 34

When using a locking plate, ancillary devices such as _____ or _____ should be considered.

Answer 34

intramedullary pins, second plates

Question 35

The size of the external fixator is directed by the size of the _____ allowed.

Answer 35

fixation pin

Question 36

When using an external fixator, the major diameter of the fixation pin should approach, but be no greater than \_\_\_% of the diameter of the bone being plated.

Answer 36

20%

Question 37

What type of pins should be used with external fixators when possible? These penetrate both \_\_\_\_\_.

Answer 37

full pins; Penetrate both cis and trans cortex

Question 38

What is an alternative to using full pins with external fixators?

Answer 38

Double connecting rods with half pins

Question 39

How many pins should engage bone on each side of the fracture when using an external fixator?

Answer 39

3

Question 40

\_\_\_\_\_ profile pins should be used and _____ for transfixation pin should be pre-drilled.

Answer 40

Positive, pilot holes

Question 41

Pins should be placed _____ to the long axis of the bone when possible.

Answer 41

perpendicular

Question 42

Pins should be placced near the _____ of the bone, as well as _____ to the fracture.

Answer 42

ends, close

Question 43

What size connecting rods should be used with an external fixator?

Answer 43

large

Question 44

When using an external fixator, clamps should be placed close to, but not touching the \_\_\_\_\_.

Answer 44

skin

Question 45

What types of fractures require lag screws?

Answer 45

long oblique

Question 46

Lag screws should be placed _____ to a fx line.

Answer 46

Perpendicular

Question 47

Bone likes \_\_\_\_\_.

Answer 47

compression