SA Fracture Treatment Flashcards
What are the fracture treatment options in SA practice?
- Intramedullary pin and cerclage wire
- Plating ( +/- compression)
- Intramedullary nail
- External fixator
- Pin and tension band
What are the advantages of using intramedullary pin?
Simple
Cheap
Excellent at counteracting bending forces
What are the disadvantages of using intramedullary pin?
Poor ability to counteract compression
Require other support options e.g. cerclage wire
If fracture is transfers rotation can occur
What are the methods of inserting IM pins?
Normograde
More difficult
Allows accurate placement
Avoid sciatic nerve in femur
Avoids entering stifle in tibia
Retrograde
Easier
Loss of control of where proximal part lies
Describe normograde insertion
Pin is placed from proximal end of proximal fragment
Small skin incision made and pin seated into bone
Pin is positioned in medullary cavity and advanced to just proximal of fracture
Reduces fracture
Then pin is pushed into distal segment
Describe retrograde placement
Pin enters proximal fragment distally
Leaves proximal bone and small wound is made and pin pushed through
Pin grasped by the Jacob’s chuck pulled proximally until distal end is just proximal to fracture
Fracture is reduced and pin driven towards distal fragment
What are cerclage wires?
An orthopaedic fixation/stabilisation wire placed to approximate fractured bone fragments
Usually in combination with intramedullary pin
What are the benefits of cerclage wires?
Counteract compression
What are the disadvantages of cerclage wires?
Don’t prevent rotation if fracture is transverse
What else can be used in combination with IM pin?
External fixator
* Combination is strong and prevents rotation and compression
Plates
* Also very strong and prevents rotation and compression
Intramedullary interlock nail
* Rarely used
* Excellent against bending, axial compression and torsion/shear
* Only useful in straight bones
* Require special jig to allow screw to enter nail
Where are plates applied?
Tension side of long bones
What are the advantages and disadvantages of plates?
Advantages
* Very versatile
○ Various types are available
* Protect against axial compression and rotation forces
Disadvantages
○ Less good at preventing bending
○ Due to not being along central axis of bone
Also due to cyclical loading when animal weight bares
What are the types of plates and their functions?
Buttress plate
○ Strong central section that bridges a comminuted section of the fracture
○ Plate takes all the load
Neutralisation plate
○ Allows reconstruction of the fracture
○ Acting as a scaffold and taking some of the load
The rest being taken by the reconstructed bone
Compression plate
○ Compresses the fracture by making use of eccentrically placed screws in an oval screw hole
○ The screw starts its flight at the top of the slope and when tightened it moves down the slope and shifts the one fragment towards the fracture hence compressing it
○ When used this way the bone takes all of the load
What is a non-locking plate?
Older
○ Requires the plate to adhere to the screws by friction
○ Also applies to the plate and bone
○ Thought that this affects the periosteal blood flow to the fracture site
What is a locking plate?
Newer
Screw fits into a thread within the plate
○ The diameter of the screw that engages in the plate is generally greater than that which engages the bone
What is an external fixator?
- Series of pins placed through skin into bone
○ Connected with connecting bar
○ Pins attached to bar with clamps or epoxy resin
○ May be threaded or triangulation of pins prevents them being pulled out
As a sole means of fixation at least 3 pins should be placed above and below the fracture
What are the advantages of external fixators?
- Very versatile
○ Can counteract all forces applies if in combination with IM pin - Useful for open fractures
○ Open wound management
* - These implants can be used in certain bones
○ E.g. the femur, tibia and humerus to augment IM pin fixation - Can also be used to manage mandibular fractures
What are the different configurations of pin placement for external fixators?
○ Uniplanar
○ Biplanar - stronger
○ Unilateral
○ Bilateral - stronger
What are the disadvantages of external fixators?
- Pins prone to infection
- May be discharge
○ Especially where pins pass though large muscle masses - Require frequent examination
- May require staging down
○ Removing a few pins to change load bearing from fixator to bone - May require several follow up radiographs
- May be discharge
What are avulsion or tension fractures?
Caused by distractive forces generated internally
as a result are exposed to distractive forces while healing
How can you treat avulsion or tension fractures?
Lag screws
Tension bands and pins
What is a lag screw method?
- Over-drill in proximal fragment (glide hole)
- Thread in far fragment
- As we tighten the screw, distance of fracture reduces
○ Pulls far side towards near
Used to produce rigid fixation and counteracts distractive forces
What is a tension band and pin method?
- Use distractive forces to make compressive force
- The fracture is reduced
○ I.e. aligned and then two pins are used to fix it in position. - Figure of 8 of wire is applied opposite the distractive force and the two arms are tightened
- Wire tightened and pulling in the opposite direction to the distractive force
○ Resultant (Pythagoras’ parallelogram of forces) is a compressive force applied to the fracture
- The fracture is reduced
