15 – External Skeletal Fixation Flashcards
External skeletal fixation
- Transversely oriented pins connect the bone to a framework outside of the limb
- *controls ALL forces that act on a fracture, providing you choose a strong enough configuration
What are the different transfixation pin types?
- Smooth
- Negative profile, end-threaded (interface)
- Positive profile, end-threaded (interface)
- Positive profile, centrally-threaded (centerface)
- **we almost always use THREADED ($30 for positive profile, $5-10 for negative profile)
What are 2 major types of connecting bars?
- *things on outside
- Rods and clamps
- Acrylic
What are some rods and clamp examples?
- Kirschner-Ehmer apparatus
- Securos and SK
- Steel and carbon fiber fords
What are some acrylic connecting bars?
- Methylmethacrylate
- Thermoplastic
- Acrylic putty
What are the advantages of rod-and-clamp system?
- Uniformly strong
- Bone is stabilized once you have the framework built
- Construct is adjustable if you don’t like positioning of something
What are the disadvantages of rod-and-clamp system?
- Pins have to be placed (more or less) in a straight line
- Limited angling possible
- Pins must be of similar size
What are the advantages of acrylic and thermoplastic connecting bars?
- Pins don’t have to be in a straight line
- Pins don’t have to be in a straight line
- Pin sizes can vary
- Many freeform configurations
- CHEAP
What are some disadvantages of acrylic and thermoplastic connecting bars?
What are some disadvantages of acrylic and thermoplastic connecting bars?
What type of ESF is this?
Type Ia
What type of ESF is this?
Type II
What type of ESF is this?
Type Ib
*very very strong
-useful for femur and humerus where you couldn’t get another bar on the other side
What type of ESF is this?
Type III
*too strong so not used often
IM Pin-ESF Tie-In
- Good axial alignment of bone
- Good bending control with fewer transfixation pins
- IM can’t migrate
- Stronger than pin combined with fixator but NOT tied in
- *can only be used in bones appropriate for IM pining
What bones are appropriate for IM pinning? (IM Pin-ESF Tie-In)
- Femur
- Tibia
- Humerus
- A few etceteras
-use little pins
-flexible wires and then tensioned at right angles (ex. like a tennis racket)=lots of strength
-if getting some axial motion=promotes fracture repair
What is distraction osteogenesis?
- Do with circular external fixators
- Can do bone lengthening: bone will form in the gap
- Can use to bridge a gap: make a new gap and fill in gap and the cut section will ‘grow’ back
Transfixation cast
- Mostly people, cattle and horses
- Cast: get good bending and torsion control
o Still have the joint above mobile
Transfixation splint
- Ex. used in bunnies (fragile bone and need to bend legs)
What are the ‘rules’ for ESF transfixation pins, amount and size?
- Minimum of 3 pins per major fragment
- Fewer pins per fragment acceptable IF ESF is tied in to an IM pin (then minimum of 1 per major fragment)
- Pins should NOT exceed 25% the diameter of the bone at that point
What are the rules for ESF transfixation pins placement?
- Place one pin in each fragment close to the joint
- Place one pin in each fragment close to the fracture (no closer than 0.5cm from edge though)
- Space other pins in between
- *all pins must fully penetrate BOTH cortices of the bone
What are the rules for connecting bars?
- Closer the bar is to the bone=stronger the fixator, but
o Clamps and rods too close to skin=nasty rub sores - *solution=place clamps/bars a finger’s width away from skin
ESF postoperative care
- Pins are placed through stab incisions
o Takes 5 days for granulation tissue to form in pin tracks
o Until that time=pad soft tissues between pins
o Afterwards=leave pin tracks open to air and pad connecting bars
What are the advantages of ESF?
- Minimal disruption of blood supply to bone
- Hardware is removed w/o general anesthesia when fracture is healed
o Can be staged to gradually transfer weightbearing forces back to the bone - Anatomic reconstruction of bone is NOT necessary
- Generally=strongest method for fixing tibial fractures
- Good for fractures with relatively short proximal or distal fragments
- Joints can be spanned if necessary
- Relatively inexpensive set up
What are the limitations of ESF?
- Limited applicability for bones with lots of muscle mass (femur, humerus, ilium)
- Some owner vigilance required
- Less familiar system for many vets
- Hardware DOES need to be removed eventually
What is ESF a good choice for?
- Open fractures, degloving injuries
Pin track drainage: where/why might it occur
- Loose pins
- Pins going through a lot of muscle
- High-motion areas
What is the treatment of pin track damage?
- Antibiotic therapy may work short-term
- Remove or replace offending pin
