Lecture 7: External Fixation- boring Flashcards
What are advantages of external fixation compared to internal?
allows for post op adjustments
minimally invasive
adjustable fracture alignment
can be removed w/o general anesthesia
clamps and rods can be used
Acrylic frames for ESF can be used on ____ bone, but are especially useful in _____ fractures and ____ patients
any bone
mandibular fractures
“pocket pets”
Disadvantages of ESF system compared to internal fixation
pins penetrate soft tissue- may impair muscles, vessels, nerves, possible entry point for contaminating bacteria
mechanical disadvantage- greater distance from bone
req’s more post op care necessary
not used on aggressive patients
What is a half pin?
Basically doesnt go all the way through the leg
threads on one side, always start on friendly side of bone- less muscle and tissue to go through,
half pin threads into bone until full thread of pin is through the far side of far cortex
What is a full pin?
BASICALLY goes all the way through the leg
starts on friednly side, push and when see tissue on far side push out then stop, make incision, and then keep going through until thread sare on the outside
What is a type I-a fixation pin?
unilateral, uniplanar
all pins in same plane, weak in opp force
What is a Type I-b fixation
unilateral, biplanar
two planes neutralize forces
Type I a/b are applicable to what bones? which ones must I-b be modified to be used on?
All weight bearing long bones- tibia, radius, femur, humerus
I-b must be modified to be used on femur/humerus
What are the 2 connections used for frames? Which is stronger?
traditional linkage
diagonal- stronger
What is IM “tie in” configuration?
adds strength when the fixation frame must be placed at great distance away from the bone
useful on femur and humerus
usually included as part of a type I-a or I-b construct
when used on the antebrachium, fixator is applied to the radius,
When is a type II contraindicated?
They are NOT applicable on the humerus/femur
they are too close to the trunk
What is a type II configuration?
bilateral, uniplanar
most useful on the TIBIA
What is a type III configuration?
it is a Type I-a + II
bilateral, biplanar- builds scaffold around 3 sides of the bone
again NOT applicable to humerus/femur
What is meant by minimal emphasis biology/ maximal strength?
Has to do with Type II/III configurations
min biology- use full pins strategically, then fill in with half pins
max strength- would use all full pins
What is the key principle of pin diameter?
thread diameter 25% of bone diameter-
too large cause fractures, too small doesnt do anything
What is the key principle of appropriate pin number?
minimum of 3 per segment, 3 proximal and 3 distal
this distributes force when walking keeping the implant tight
What is the key principle of pin placement?
place them in mechanically sound bone, try to stay one bone diameter from the fracture to keep intact bone
What is the key principle of drilling?
pins are applied to pre drilled hoes, use slow speed power insertion
What is the key principle of frames?
proper frame size and geometry for fracture being fixed
What is the key principle of pin/frame lengths?
want the optimal, short is best
What is the key principle of hygiene?
need proper pin tract hygiene until development of granulation tissue
What is the key principle of dis-assembly?
take advantage of adjustability, “staged dis assembly decrease force as you take it apart
What is the key principle of bandaging?
need a protective bandage over frame the entire time they have it on
Measurements are most accurate in what projection?
lateral
T/F
Hanging limb technique provides approximate fracture alignment for the femur and humerus but should never be used for the radius or ulna
FALSE
opposite is true
T/F
it is imperative that radiographs be used and ESF pins are over-layed to determine the correct pin size as part of pre op planning
True
What two things do you need to pay attention to while drilling?
tactile and auditory feedback
Because you cannot see your target, what do you need to do to ensure you are in the center of the bone?
Drill to bone, walk off either edge to find center, want to start drilling, feel resistance, then punch through, then second resistance, keep spinning and lift hand up
T/F
When removing the drill post-drilling pilot hole you must spin in the clockwise direction
TRUE
What size do you want your pilot hole drill bit?
1/10th smaller than the the core diameter of pin, this way the threads will cut into the bone
The size of clamp to used is determined by what?
the pin diameter
What is the difference in drilling between the pilot hole and setting a pin?
twist channel in drill bit allows debris to escape, minimizes frictional heat
when setting pins, there is no channel, must go slow to prevent frictional heat, decreases bone death around the pin
T/F
To maximize the pin-bone interface, you must make sure that the full diameter of the pin engages the far side of the far cortex
True
What is the order placement of pins?
Far-far, near-near, middle, middle
Accurate release incisions are at least __ long
1 cm
There must be a minimum of __ pins /segment?
3
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