External Skeletal Fixation (ESF) Flashcards
External skeletal fixation (ESF)
Transversely oriented pins connect the bone to a framework outside the limb
-controls all of the forces that act on a fracture if choose a strong configuration
Components of ESF
Transfixation pin types
*threaded types are most commonly used
-negative profile threads cut into the pin
-positive profile threads are rolled onto the outside of the pin
Connecting Bar options
- Rods and clamps
- Acrylic
Rods and clamps- connecting bars
-Kirschner-Ehmer apparatus
-Securos and S-K systems
- Steel and carbon fiber rods
Acrylic connecting bars
-Methhylmethacrylate
-Thermoplastic
-Acrylic putty
Advantages to rod and clamp system
-uniformly strong
-bone stabilized once the framework is built
-construct is adjustable if you don’t like positioning of something (in post op radiographs)
Rod and clamp system disadvantages
-pins have to be placed (more or less) in a staight line
-limited angling possible
-pins must be of similar size
Acrylic connecting bars
-use old tubing/hose and inject cement, acrylic, or putty etc.
Thermoplastic connecting bars
- small animals
-use thermoplastic- get wet and will set
-provides strong grip on pins
Advantages of acrylic and thermoplastic connecting bars
-pins on’t have to be straight
-pin sizes vary (great for smaller animals)
-many freeform configurations possible
-cheap
Disadvantages of acrylic/thermoplastic connecting bars
-fracture is not stable until connecting bar has set up; alignment must be held manually while this happens
-not easily adjustable once connecting bar has been set
Type Ia ESF
-connecting bar on one side, pins enter one side and don’t come out the skin on other side
Type II ESF
-weakest configuration
-have at least one pin on each end that goes completely through the other side and into connecting bar
-2 connecting bars
Type Ib ESF
**very strong; advantage for bones that you cant have connecting bars on opposite sides of each other
-2 connecting bars but 90 degree angle to the first one
-can make it stronger by connecting connecting bars together
Type III ESF
-a bit too strong, so not used much anymore
-uses 3 connecting bars
IM Pin-ESF Tie-In
-IM pin through medullary cavity prevents bending but need connecting bar to prevent tension, compression, torsion
-When the IM pin and the transfixation pins are all connected, it increases strength
Advantages of IM Pin ESF tie in
-good axial alignment of bone
-good bending control with few transfixation pins
-IM pin can migrate
-stronger than pin combined with fixator but not tied in
Disadvantage of IM pin ESF tie in
-only can be used in bones appropriate for IM pinning (femur, tibia, humerus)
Circular ESF
-fracture repair needs slight up and down movement
Circular hybrid external fixation
-uses circular fixation at one end, and connecting bar at the other
Distraction osteogenesis
- can be used for bone lengthening by gradually moving broken bone apart and then bone will fill in the gap
- Bridging the gap- make cut in the healthy bone and then allow that to fill in and eventually fill gap
Transfixation cast
-cast controls bending if attach cast to the bone (allows you to not need to have a larger cast that immobilizes the joint
Transfixation splint
allows for bending of stifle and secure fracture
Transfixation pin rules
-min 3 pins per major fragment
-fewer pins per fragment acceptable if ESF is tied to IM pin (then min 1 pin per major fragment)
-pins should not exceed 25% the diameter of the bone at that point
Placement of transfixation pin rules
-place one pin in each fragment close to the joint
-place one pin in each fragment close to the fracture
-space other pins in between
How far do transfixation pins need to go?
Must go through both cortices of the bone
*but may not need to go through the skin on the other side
WHY= will come back out
Connecting bar rules
-closer the bar is to the bone= better fixator
*but closer the clamps and rods are to the skin=rub sores
Therefore, place clamps/bars a fingers width away from the skin
ESF post op care
-pins places through stab incisions ; takes about 5 days for granulation tissue to form in pin tracks
*must pad soft tissues between pins until granulation forms, then leave pin tracks open to air and pad connecting bars
Advantages of ESF
-minimal disruption of blood supply to bone
-hardware removed without GA when fracture healed; and can be removed in stages to transfer weightbearing forces gradually
-anatomic reconstruction of bone is not needed
-usually strongest method for fixing tibial fractures
-good for fractures with short proximal or distal fragments
-can span joints if needed
-inexpensive
Limitations of ESF
-limited applicability for bones with lots of muscle mass (femur, humerus, ilium)
-some owner vigilance needed
-less familiar system for many vets
-hardware will eventually need to be removed
What is ESF good for?
-open fractures
-degloving injuries
Pin track drainage
-loose pins
-pins going through a lot of muscle
-high motion areas
Treatment of pin track drainage
Antibiotic therapy can work short term
-and remove or replace offending pins
