SA Fracture Treatment

Question 1

What are the fracture treatment options in SA practice?

Answer 1

• Intramedullary pin and cerclage wire
  
  • Plating ( +/- compression)
  • Intramedullary nail
  • External fixator
  • Pin and tension band

Question 2

What are the advantages of using intramedullary pin?

Answer 2

Simple
Cheap
Excellent at counteracting bending forces

Question 3

What are the disadvantages of using intramedullary pin?

Answer 3

Poor ability to counteract compression
Require other support options e.g. cerclage wire
If fracture is transfers rotation can occur

Question 4

What are the methods of inserting IM pins?

Answer 4

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

Question 5

Describe normograde insertion

Answer 5

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

Question 6

Describe retrograde placement

Answer 6

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

Question 7

What are cerclage wires?

Answer 7

An orthopaedic fixation/stabilisation wire placed to approximate fractured bone fragments
Usually in combination with intramedullary pin

Question 8

What are the benefits of cerclage wires?

Answer 8

Counteract compression

Question 9

What are the disadvantages of cerclage wires?

Answer 9

Don’t prevent rotation if fracture is transverse

Question 10

What else can be used in combination with IM pin?

Answer 10

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

Question 11

Where are plates applied?

Answer 11

Tension side of long bones

Question 12

What are the advantages and disadvantages of plates?

Answer 12

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

Question 13

What are the types of plates and their functions?

Answer 13

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

Question 14

What is a non-locking plate?

Answer 14

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

Question 15

What is a locking plate?

Answer 15

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

Question 16

What is an external fixator?

Answer 16

• 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

Question 17

What are the advantages of external fixators?

Answer 17

• 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

Question 18

What are the different configurations of pin placement for external fixators?

Answer 18

○ Uniplanar
○ Biplanar - stronger
○ Unilateral
○ Bilateral - stronger

Question 19

What are the disadvantages of external fixators?

Answer 19

• 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

Question 20

What are avulsion or tension fractures?

Answer 20

Caused by distractive forces generated internally
as a result are exposed to distractive forces while healing

Question 21

How can you treat avulsion or tension fractures?

Answer 21

Lag screws
Tension bands and pins

Question 22

What is a lag screw method?

Answer 22

• 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

Question 23

What is a tension band and pin method?

Answer 23

• 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