9. Principles & use of external skeletal fixation devices

Question 1

pros of external fixation

Answer 1

1.easy removal of implant
2. adjust stability
3. used in open fractures/wounds- wound cleaning
4. counteract all 5 forces (tension, compression, bending, shearing, torsion)

Question 2

what are the materials that makes up the ESF?

Answer 2

pins, clamps, connecting bar

Question 3

when are smooth pins used in ESF?

Answer 3

the smallest pins made right now are only smooth,
these are used in small animals and exotics
young animals with simple, stable fractures

concerns with loosening of the pins

Question 4

threaded: negative profile vs positive profile-transfixation pins

Answer 4

negative profile: thread length shorter than smooth length
prone to breakage at the midpoint where the thread meets smooth part(weak at thread and smooth interface)

positive profile transfixation pins- longer thread diameter than smooth, less likely to break in half
more expensive and could break cortical bone if placed incorrectly

Question 5

full pins vs half pind

Answer 5

full pins penetrate both cortices (bicortical)- and exit through the skin on both side
smooth-threat-smooth pin

half pins- only penetrate one skin surface-
smooth-thread pin

Question 6

ouwhat material is commonly used for the connecting bar?

Answer 6

carbon fiber- very light weight

aluminum and graphite are expensive

Question 7

how can you get creative with connecting bars?

Answer 7

you can make your own from acrylic or PMMA
this is especially useful in exotics

Question 8

ESF Type IA classification

Answer 8

unilateral,uniplanar

Question 9

ESF Type II classification

Answer 9

Bilateral, uniplanar
could have bending occur

Question 10

ESF Type III classification

Answer 10

Bilateral, biplanar
stiffest configuration

Question 11

ESF Type IB classification

Answer 11

unilateral, biplanar
good at preventing cranial-caudal bending

Question 12

what is Tie-in configuration?

Answer 12

this is ESF plus IM pin
this is done on humerus and femur repairs
Type 1B
Cant place Type II or Type III bc of the muscles and interference with thorax/abdoment

Question 13

surgical placement of ESF

Answer 13

asepsis
standard draping
hanging leg- helps with reductio/alignment
align fracture using a open, mini or closed approach

Question 14

pin insertion rules

Answer 14

-each pin has its own insertion
-use drill at slow speeds, NEVER hand chucks(wobble and loosening of pins
-pin is less than 20% bone diameter
-predrill hole with drill bit for positive profile pins(mandatory)

Question 15

Do not place pins in the following

Answer 15

open wounds, muscles/tendons, neurovascular bundles

Question 16

distance of connecting bars to skin

Answer 16

about 0.5cm from skin edge

too close- irritating, especially if swelling c=occurs
too far- weaker

Question 17

ESF complication

Answer 17

loosening of screws
screws break
infections
mal-union
fracture more bone during placement

Question 18

ESF advantages

Answer 18

can remove equipment without surgery
adjust stability
good for wound care/open fractures
can get good alignment & counteract all 5 forces

Question 19

ESF disadvantages

Answer 19

more client compliance heavy

pain associated with pins

more appointments

Question 20

circular ring fixators

Answer 20

1. bring bone out to length and straighten bone (help with deformities)- aka distraction osteogenesis
2. good for metaphysics fractures/distal fractures

Question 21

distraction osteogenesis

Answer 21

this is accomplished with circular ring fixation- lengthens bone/ straighten bone