Bone Screws and Plates - Betance

Question 1

Cancellous screws are used in

Answer 1

softer/spongey bone

- metaphyseal or epiphyseal bone

Question 2

Cortical screws are used in

Answer 2

harder bone

- cortex, diaphyseal

Question 3

Shaft screws are used when/how/where?

Answer 3

used for lag application in diaphyseal bone

Question 4

Cannulated screws are used when?

Answer 4

used in more difficult fractures

Question 5

Locking head screws are used when?

Answer 5

used in locking compression plates

Question 6

What is a self tapping screw?

Answer 6

it’s a cortical screw that has a head at the tip like a drill bit. It allows screw placement without predrilling a hole and tapping.

Question 7

What kind of pitch/thread does a cancellous screw have?

Answer 7

a larger pitch and a deeper thread. It can be partially or fully threaded

Question 8

What kind of pitch/thread does a cortical screw have?

Answer 8

smaller pitch and shallow threads. This allows for more threads per inch. It’s fully threaded

Question 9

what kind of thread does a shaft screw have?

Answer 9

partially threaded (AT THE DISTAL END). It’s a cortical screw!!!!!!

Question 10

Tell me about the structure of a cannulated screw

Answer 10

it has a central hollow core. K-wire holds reduced fx and acts as a guide

Question 11

what would you use a compression plate on?

Answer 11

a transverse or nearly transverse fracture

Question 12

what would you use a neutralization plate on?

Answer 12

an oblique or communicated fracture

Question 13

What would you use a bridging (buttress) plate on?

Answer 13

they basically bridge diaphyseal fractures

Question 14

What does a compression plate do, exactly?

Answer 14

allows compression of bone at the fracture site

• compression is applied by the spherical gliding principle and occurs with an eccentric loaded screw
• the plate needs to be shaped to bone
• allows for compression of the opposite cortex

Question 15

What does a neutralization plate do, exactly?

Answer 15

• anatomical reduction is accomplished with the use of lag screws or cerclage wires

Question 16

What forces does a neutralization plate protect against?

Answer 16

• rotation
• bending
• shearing forces

Question 17

Where is a bridging plate secured to?

Answer 17

proximal and distal fracture fragments. It spans the comminuted part of the fracture

Question 18

what does a bridging plate prevent?

Answer 18

prevents axial deformity as a result of shear or bending forces

Question 19

How can a dynamic compression plate be used?

Answer 19

• neutralization
• compression
• bridge plating

Question 20

Limited Contact Dynamic Compression Plates can be used in 3 different ways:

Answer 20

• compression
• neutralization
• bridging functions

Question 21

LC-DCPs do what to cortical perfusion?

Answer 21

improves it!!! it has decreased plate to bone contact. It also reduces stress concentration at screw holes

Question 22

what functions can a Locking Compression Plate have?

Answer 22

• compression
• neutralization
• bridging function

Question 23

what else can a locking compression plate be called?

Answer 23

an internal fixator

Question 24

What specific ortho thing is the LCP good for?

Answer 24

Minimally invasive plate osteosynthesis (MIPO)! It has a tapered tip.

Question 25

which type of plate would you use in an area that requires complex plate contouring such as the mandible?

Answer 25

A reconstruction plate! It allows for contouring in an additional plane. It's not as strong as a DCP though.

Question 26

What plate would you use in super thin bones?

Answer 26

A VCP (veterinary cuttable plate). It's relatively week, can be stacked, and does not have any compression function

Question 27

What plate would you use in a chihuahua thing?

Answer 27

miniplates! They are teeny tiny and have self-tapping screws

Question 28

What plate classification is a string of pearls?

Answer 28

A locking plate. It can contour in any direction

Question 29

What screws would you use for a string of pearls plate?

Answer 29

unicortical screws.

Question 30

Does the string of pearls compress?

Answer 30

Nope! It neutralizes or bridges

Question 31

What kind of plate would you use in a hip dysplasia patient?

Answer 31

Triple Pelvic Osteotomy plates. It changes the angle

Question 32

What kind of plate would you use in an area with little soft tissue covering?

Answer 32

tubular plates

Question 33

Where do you place the bone plate on the bone?

Answer 33

On the tension side of the bone. Plates will likely fail on the compression side

Question 34

What do plates achieve?

Answer 34

They convert distracting/tension forces into compression forces with weight-bearing

Question 35

How many cortices on each side of the fracture line should you engage when bone plating?

Answer 35

at least 6! (at least 3 screws)

Question 36

Where should the bone plate span?

Answer 36

the diaphysis of the bone if possible

Question 37

How far from the fracture line should screws be placed?

Answer 37

at least 5mm

Question 38

When do you place screws in a fracture line?

Answer 38

ONLY if a lag/position screw!

Question 39

Where is an interlocking nail placed?

Answer 39

a stainless steel nail placed within the MEDULLARY CAVITY. (it gets locked to the bone by screws that cross the bone and pass through holes in the nail)

Question 40

What are interlocking nails used for?

Answer 40

mid diaphyseal fractures of the humerus, femur, and tibia

Question 41

How do you place interlocking nails, retrograde or normograde?

Answer 41

NORMOGRADE

Question 42

what forces do interlocking nails resist?

Answer 42

bending, shearing, and rotational forces