Written Exam 2 - Fracture Fixation Methods 2

Question 1

what are the advantages & disadvantages of direct reduction?

Answer 1

advantages - precise reconstruction & limb shares load with the implant

disadvantages - dissection of soft tissues & disruption of healing & blood supply

Question 2

what are the advantages & disadvantages of indirect reduction?

Answer 2

advantages - blood supply & soft tissues preserved, access to wounds around fx site, neutralizes load-bearing forces, can make post-op adjustments

disadvantages - implant sustains all of the load share & improper anatomic alignment, upsetting to owner, prematurely can loosen, associated infection, can get hung on objects, & maintenance

Question 3

what is an external skeletal fixator?

Answer 3

series of transosseous (bicortical) pins or wires incorporated into an extracorporeal frame that can be used as primary or adjunctive stabilization

Question 4

what kind of support does an external fixator provide?

Answer 4

bending - good to excellent

axial - excellent

rotational - good to excellent

Question 5

what is the difference between unilateral & bilateral frame configurations?

Answer 5

all pins are bi-cortical!!!

unilateral - penetrates 1 skin surface

bilateral - penetrates 2 skin surfaces

Question 6

why do you need to angle smooth pins?

Answer 6

they have weak pull-out strength & don’t grip the bone as well

Question 7

T/F: moving the frame configuration closer to the bone increases the stiffness of construct

Answer 7

true

Question 8

what is the stiffness of fixation pin related to?

Answer 8

the distance between the cis-cortex & the connecting clamps

Question 9

what does a IM pin tie in do for a type Ia ESF?

Answer 9

increases bending support

Question 10

what type of ESF is this?

Answer 10

type Ia - ESF is in one plant & pins only penetrate 1 skin surface (half pin)

Question 11

what kind of ESF is this?

Answer 11

type Ib - biplanar type I configuration

stronger than uniplanar - fixator pins still only go through one skin surface

Question 12

what type of ESF is this?

Answer 12

type II - pins penetrate 2 skin surfaces (full pins), can span joints, distal limbs

Question 13

why can’t you use a type II ESF on a humerus or femur?

Answer 13

anatomical limitations of the animal

Question 14

what type of ESF is this?

Answer 14

type II modified - utilizes both half & full pins, easier to apply with comparable stability

Question 15

what type of ESF is this?

Answer 15

type III - strongest of the frame types, most expensive, usually used on the tibia & maybe radius

Question 16

what are the advantages of using positive profile pins for ESF?

Answer 16

superior stiffness & axial extraction characteristics & effective centrally positioned pins

Question 17

which IMEX SK external fixation system is shown correctly?

Answer 17

A

Question 18

what is the strongest option of connecting bar?

Answer 18

titanium

Question 19

what is the size used for pins in ESF?

Answer 19

pin diameter should not exceed 30% of the bone diameter & the beveled tip of the pin should completely penetrate the far cortex

Question 20

how many pins should be used in ESF?

Answer 20

as many as possible - minimum 2 above & 2 below

Question 21

which clamps have been applied appropriately?

Answer 21

the ones on top - you want the clamps closest to the bone

Question 22

how should pins be applied?

Answer 22

drilling - high torque low speed drill

Question 23

why drill a pilot hole first?

Answer 23

theorized to decrease mechanical damage, heat generated during insertion, pull-out strength, & post-op morbidity

Question 24

what is the recommendation for predilling?

Answer 24

predill with a bit that has a core diameter 0.1 mm < core diameter of the corresponding fixation pin

Question 25

T/F: reduction of the fracture should be performed before placing the remainder of pins after the 1st two have been placed

Question 26

where should bars & clamps be placed in regards to an ESF?

Answer 26

as close to the limb as possible - use the clamp in configuration to shorten this distance

Question 27

what aftercare is needed for ESF?

Answer 27

pad heavily under the bars to reduce swelling, RJ bandage, cover open wounds with sterile dressing, remove bandages in 2-5 days, wrap bars to protect from injury, & keep clean

Question 28

when will frames of an ESF be removed?

Answer 28

minimum 8-16 weeks after in adult animals - under heavy sedation only

cut full pins short, clean, & pull with wire twisters or vice grips, clip/clean & bandage for a few days

rest 3-4 more weeks - must do radiographic assessment prior!!!!

Question 29

what can you do to increase axial stiffness for a type I ESF?

Answer 29

additional connecting bar to increase axial stiffness by 2.5X

Question 30

what are type Ia/Ib frames ideal for?

Answer 30

simple fractures

Question 31

what are type II/III ESF frames ideal for?

Answer 31

complex fractures

Question 32

T/F: positive profile pins & thread pins are better than smooth & negative profile pins

Answer 32

true

Question 33

what is the effect of a loose wire upon the healing & stability of a fracture?

Answer 33

damages bone blood supply, decreases stability, & negatively impacts bone healing

Question 34

how does the surgeon decide on the size of transosseous pins needed for an ESF? how is it performed?

Answer 34

should be approximately 25% of the fracture bone diameter - pre-op calibrated radiographs for measuring

Question 35

why are threaded pins applied in a perpendicular fashion?

Answer 35

threaded pins grip bone better than a smooth pin & have a higher pull-out strength

Question 36

why would you avoid using cerclage wire in a comminuted fracture?

Answer 36

smaller fracture pieces can collapse into the fracture when wires are tightened

Question 37

in younger patients, what should be considered when placing transosseous pins into a bone?

Answer 37

be aware of growth plates - want to avoid entering them, can cause probles

Question 38

how can you increase the strength of a modified type II ESF?

Answer 38

increase size & number of frame, increase number of pins used per bone fragment, & maximize pin diameter

Question 39

what post-op healing complications are associated with a modified type II ESF?

Answer 39

increased soft tissues swelling, superficial skin infections are expected, longer healing time due to the involvement of more soft tissue structures