External Skeletal fixation (lewis)

Question 1

Indications for external skeletal fixation

Answer 1

Comminuted  fx
Open fx
infected/nonunion fx
athrodesis
Trans-articular stabilization
limb deformities

Question 2

main advantage of external fixation

Answer 2

counteract axial (compressional), bending, and rotational forces

Question 3

what does Type 1 half pin splint mean

Answer 3

pins pass through both cortices but only one skin surface

Question 4

Type 1 unilateral

Answer 4

pins go in on same side

Question 5

Type 2 full pin

Answer 5

pins pass through both cortices and two skin surfaces

Question 6

Is a type 1 or 2 fixator more stable

Answer 6

2

Question 7

What locations are type 2 fixators limited to

Answer 7

distal to elbow or stifle

Question 8

Modified type 2 use both

Answer 8

half and full pin splintage

Question 9

Advantages of modified type 2

Answer 9

easier to apply with comparable stability

Question 10

Type 3 splint

Answer 10

both half and full pin
Biplanar
bilateral

Question 11

Characteristics of type 1 fixator

Answer 11

half pin
uniplanar
unilateral

Question 12

Characteristics of type 2 fixator

Answer 12

full pin
uniplanar
bilateral

Question 13

Indications of half pin

Answer 13

cantilever bending

less bulk

Question 14

Indication of full pin

Answer 14

four point of bending

more stable

Question 15

advantage of partially threaded pin

Answer 15

greater resistance to axial extraction in cortical bone

Question 16

Advantage of negative profile pin

Answer 16

less resistant to bending forces because of smaller diameter

Question 17

Advantage of positive profile pin

Answer 17

superior stiffness and axial extration

Question 18

What is the weakest link in an external fixation construct

Answer 18

bone-pin interface

Question 19

Disadvantage of Kirschner-Ehmer apparatus

Answer 19

really difficult to place

Uses lots of pins

Question 20

What does the SK system allow

Answer 20

pre-drilling of pilot holes and increased variability in fixation pin diameter with better mechanics

Question 21

What should you place pins through for external fixators

Answer 21

small incisions

Question 22

What should the drill core be compared to the fixation pin

Answer 22

.1mm smaller

Question 23

What speed/torque should the drill be for fixations pins

Answer 23

low speed

high torque

Question 24

Fixation pin should not exceed what percentage of the diameter of the bone

Answer 24

30%

Question 25

Advantages of acrylic fixators

Answer 25

Pins variable diameter, don’t have to be placed in same longitudinal plane,
Radiolucent
Min. distance between connecting column and the cis-cortex of the bone
Lightweight
Limited inventory and expense

Question 26

Disadvantages of acrylic fixators

Answer 26

Difficult to maintain reduction if used for primary fixation
Hot, can burn
Fumes are toxic
Difficult to adjust