fracture fixation methods

Question 1

Goals of fracture fixation:

Answer 1

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

Question 2

For a fracture to heal you need:

Answer 2

• Stability
• Blood supply

Question 3

carpenter vs gardener approach to fracture fixation

Answer 3

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…

Question 4

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

Answer 4

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

Question 5

Methods of Fixation

Answer 5

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

Question 6

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

Answer 6

• 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…

Question 7

Golden Rule of cast placement

Answer 7

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

Question 8

Some bones/Fx should never be casted:

Answer 8

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

Question 9

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

Answer 9

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

Question 10

External Fixator Types

Answer 10

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

Question 11

External Fixation
- pros and cons

Answer 11

• 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

Question 12

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

Answer 12

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

Question 13

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

Answer 13

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

Question 14

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

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

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

Question 17

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

Answer 17

• 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

Question 18

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

Answer 18

• 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

Question 19

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

Answer 19

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

Question 20

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

Answer 20

• 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