Written Exam 2 - Fracture Fixation Methods 2 Flashcards
what are the advantages & disadvantages of direct reduction?
advantages - precise reconstruction & limb shares load with the implant
disadvantages - dissection of soft tissues & disruption of healing & blood supply
what are the advantages & disadvantages of indirect reduction?
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
what is an external skeletal fixator?
series of transosseous (bicortical) pins or wires incorporated into an extracorporeal frame that can be used as primary or adjunctive stabilization
what kind of support does an external fixator provide?
bending - good to excellent
axial - excellent
rotational - good to excellent
what is the difference between unilateral & bilateral frame configurations?
all pins are bi-cortical!!!
unilateral - penetrates 1 skin surface
bilateral - penetrates 2 skin surfaces
why do you need to angle smooth pins?
they have weak pull-out strength & don’t grip the bone as well
T/F: moving the frame configuration closer to the bone increases the stiffness of construct
true
what is the stiffness of fixation pin related to?
the distance between the cis-cortex & the connecting clamps
what does a IM pin tie in do for a type Ia ESF?
increases bending support
what type of ESF is this?
type Ia - ESF is in one plant & pins only penetrate 1 skin surface (half pin)
what kind of ESF is this?
type Ib - biplanar type I configuration
stronger than uniplanar - fixator pins still only go through one skin surface
what type of ESF is this?
type II - pins penetrate 2 skin surfaces (full pins), can span joints, distal limbs
why can’t you use a type II ESF on a humerus or femur?
anatomical limitations of the animal
what type of ESF is this?
type II modified - utilizes both half & full pins, easier to apply with comparable stability
what type of ESF is this?
type III - strongest of the frame types, most expensive, usually used on the tibia & maybe radius
what are the advantages of using positive profile pins for ESF?
superior stiffness & axial extraction characteristics & effective centrally positioned pins
which IMEX SK external fixation system is shown correctly?
A
what is the strongest option of connecting bar?
titanium
what is the size used for pins in ESF?
pin diameter should not exceed 30% of the bone diameter & the beveled tip of the pin should completely penetrate the far cortex
how many pins should be used in ESF?
as many as possible - minimum 2 above & 2 below
which clamps have been applied appropriately?
the ones on top - you want the clamps closest to the bone
how should pins be applied?
drilling - high torque low speed drill
why drill a pilot hole first?
theorized to decrease mechanical damage, heat generated during insertion, pull-out strength, & post-op morbidity
what is the recommendation for predilling?
predill with a bit that has a core diameter 0.1 mm < core diameter of the corresponding fixation pin
T/F: reduction of the fracture should be performed before placing the remainder of pins after the 1st two have been placed
where should bars & clamps be placed in regards to an ESF?
as close to the limb as possible - use the clamp in configuration to shorten this distance
what aftercare is needed for ESF?
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
when will frames of an ESF be removed?
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!!!!
what can you do to increase axial stiffness for a type I ESF?
additional connecting bar to increase axial stiffness by 2.5X
what are type Ia/Ib frames ideal for?
simple fractures
what are type II/III ESF frames ideal for?
complex fractures
T/F: positive profile pins & thread pins are better than smooth & negative profile pins
true
what is the effect of a loose wire upon the healing & stability of a fracture?
damages bone blood supply, decreases stability, & negatively impacts bone healing
how does the surgeon decide on the size of transosseous pins needed for an ESF? how is it performed?
should be approximately 25% of the fracture bone diameter - pre-op calibrated radiographs for measuring
why are threaded pins applied in a perpendicular fashion?
threaded pins grip bone better than a smooth pin & have a higher pull-out strength
why would you avoid using cerclage wire in a comminuted fracture?
smaller fracture pieces can collapse into the fracture when wires are tightened
in younger patients, what should be considered when placing transosseous pins into a bone?
be aware of growth plates - want to avoid entering them, can cause probles
how can you increase the strength of a modified type II ESF?
increase size & number of frame, increase number of pins used per bone fragment, & maximize pin diameter
what post-op healing complications are associated with a modified type II ESF?
increased soft tissues swelling, superficial skin infections are expected, longer healing time due to the involvement of more soft tissue structures
