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3. Cat & Dog 2 > fracture fixation methods > Flashcards

fracture fixation methods Flashcards

1
Q

Goals of fracture fixation:

A

Return to full function
* Bone reconstruction
* Preservation of the blood supply
* Stable fixation
* Early active, pain free movement and full weight bearing

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2
Q

For a fracture to heal you need:

A
  • Stability
  • Blood supply
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3
Q

carpenter vs gardener approach to fracture fixation

A

Carpenter
* Anatomical reconstruction
* Stable fixation
> Reconstruct all fragments
> Better initial stability
<><><><>
Gardener
* Restore joint alignment
* Stable fixation
* Bridging of the fracture
> No attempt to reconstruct
> Better viability
<><><><><><><><>
No clear winner or loser
Bone needs both
Choice depends on
-fracture
-skills
-equipment
-preference…

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4
Q

stabilizaing a fracture mean neutralizing what?
- what does this mean for our repair methods?

A

5 forces
* Stabilizing a fracture means neutralizing all 5 forces
* Not all implant can counteract all forces
> Use a combination of implants
<><><>
compression, tension, shear, bending, torsion

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5
Q

Methods of Fixation

A
  • Casts
  • External fixators
  • Intramedullary pins/cerclage wires
  • Interlocking nails
  • Tension band
  • Bone plate
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6
Q

External Coaptation (cast)
- issues
- when to use?

A
  • Never provide complete immobilization!
  • Cast complications increase with duration!
    > Stable fracture – Simple transverse
    > Midshaft
    > (Reducible or) non displaced
    > Distal extremity – distal to stifle and elbow
    > Expected to heal rapidly – young animals
    <><>
    Reserved for specific fractures…
    Most fractures should not be casted…
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7
Q

Golden Rule of cast placement

A

To correctly immobilize a fracture, the cast MUST extend from the toes to at least one articulation higher than the fracture

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8
Q

Some bones/Fx should never be casted:

A
  • Femur
  • Humerus
  • Radius (in miniature breeds!)
    > 80% complication rate!
    => Non-union
    => Mal-union
    > Size and poor vascularity
  • Comminuted fractures
  • Open Fx
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9
Q

External Fixators
- what is it made of?
- uses?
- advantages?

A

External apparatus composed of :
* Transfixation pins
> Transcutaneous
> Bicortical
* Connecting bars
* Clamps
> bars and clamps may be epoxy or acrylic instead
<><><><>
* Very versatile
> Unlimited configurations
> Can be very stable
* Preservation blood supply
* Can be inexpensive

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10
Q

External Fixator Types

A
  • Type 1: Uniplanar, unilateral
  • Type 1b: Biplanar, unilateral
  • Type 2: Uniplanar, bilateral
  • Type 3: Biplanar, bilateral
  • Ring fixator or Ilizarov
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11
Q

External Fixation
- pros and cons

A
  • Versatility, little equipment needed
  • Minimize surgical approach
    > Very good for compromised fractures
    > Open fractures
  • Removal without general anesthesia
  • Reasonable cost…
  • BUT
  • Technically difficult
  • High maintenance!
    > Daily cleaning of pins
  • High morbidity
    > Pin failure
    > Pin infection
  • Cumbersome
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12
Q

Intramedullary Pins
- what are they
- what they are good and bad at
- how are they used?

A

Smooth metal pins inserted into the medullary cavity of long bones
* Kirschner wires or K-wires 0.9mm-1.5mm
* Steinmann pins >1.5 - 6.5 mm
<><>
Resist bending very well
* Do not resist any other force
<><>
Used only with other methods of fixation:
* Cerclage wires
* Plates
* External fixators
> these 3 control the other forces

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13
Q

Pin Insertion
- normograde vs retrograde
- how we do it? things to avoid?
- considerations?
- not for what bone? why?

A

Normograde:
* From one extremity of the bone toward the fracture
<><>
Retrograde:
* From the fracture toward the extremity
<><>
* Pin must be cut short to avoid soft tissues
* Must avoid joint penetration
> The radius CANNOT be pinned
=> Articular surfaces on both sides

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14
Q

Cerclage Wires
- what are they?
- use?
<><>
Rule for Cerclage Wire Use

A

Pliable stainless steel wire
* Size in “gauge” ie 16g (1.25mm) to 22g (0.6mm)
* Used to stabilize large fragments
* Secured by twisting or eyelet
<><>
Rule for Cerclage Wire Use
* Never used alone
* Full cylinder of bone MUST be reconstructed anatomically
* ONLY for SIMPLE and LONG OBLIQUE fractures
* Must be and must remain tight
* At least 3 to 4 cerclages

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15
Q

what happens if we:
- try to use cerclage wires on a fracture that is too short?
- what if we only use one?

A
  • Fragments will shear
    > Cannot generate enough compression and fragments will shear
    <><>
    Minimum of two
  • if only one, poor resistance to bending
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16
Q

Tension Band
- used for what type of fractures?
- anatomic locations?
- how does it work?

A

Only used for tension fractures
* Tendon or ligament attachments
> Tibial tuberosity
> Greater trochanter
> Tibial malleolus
> …
<><><>
2 Pins and figure-of-eight wire
* Counteract tension forces
* Converts tension forces into compression
<><>
* Pins prevent displacement of fragment
* Wire resist tension and convert into compression

17
Q

Interlocking Nails
- what are these?
- how do they work? use?
- not for what?
- good for what?

A
  • Large intramedullary implants
  • Bone fragments are locked by guiding bolts
    through the bone and inside holes in the nail
  • Can be alone used in almost all fracture types
  • NOT for radius
  • Good for open fractures
  • Good for comminuted fractures
18
Q

Bone Plates and Screws
- how do they work?
- sizing?
- how to use them

A
  • Stabilization is achieved using metal plates secured to the bone with screws
  • Variety of sizes, lengths and shapes
  • The size of the plate = Ø of the screw in mm
    <><>
  • Contoured to the bone
    > Must match bone surface
  • 3 to 4 screws per fragment
  • Provide excellent stability
  • Requires extensive approach
    > More soft tissue damage
    > Increased risk of infection
    <><>
    Uses:
  • Depends on fracture type:
  • Compression: Full bone support and compression of fragments by the plate
  • Neutralization: Bone reconstructed but does not provide full support
    > Plate protects repair
  • Bridging: No bone support, implant supports all the load
    <><>
    Plates can be combined with other implants
  • Plate and Pins (aka plate/rod)
  • Plate and cerclages
  • Double plate
19
Q

Locking Plates
- what is this? purpose?
- advantages?

A

Bone plate in which the screw locks into the plate
* Screws threads into plate (cannot angulate)
* Does not rely on friction of the plate against the bone
* Plate does not need to touch the bone
> Less biological impact on the bone
> Better fixation in small or poor quality bone

20
Q

Minimally Invasive Osteosynthesis
- what is this?
- pros and cons

A
  • Not specific to a type of implant… more a philosophy
  • Surgery perform through small incisions remote to the fracture in order to decrease biological impact
    > Often with use of fluoroscopy
    <><>
  • Decrease morbidity
    > Infection?
  • Faster recovery
  • Increases healing?
    But
  • Difficult: Requires lots of practice
  • Long surgical times
  • Exposure to radiation
  • Mal-alignment of fracture

3. Cat & Dog 2 (50 decks)

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