small animal fracture managment

Question 1

What are the important features to be examined in a trauma case?

What is the mnemonic that we adopt in these cases?

How do we assess these things?

Answer 1

ABC
Airwayss, Breathing, circulation

will die of these things not a broken bone

assess breathing and respiration
Any evidence of blood loss assessed by mucosal colour and pulse volumes (thready pluse)

Assess integrity of the urinary tract-is the bladder palpable?

Are there any obvious neurological abnormalities?

Question 2

with a dyspeoeic trauma cat what is the initial management plan?

Answer 2

If markedly dyspnoeic-exploratory chest drainage or T Fast/POCUS ultrasound

Cage confinement, rest and observation. (handle the distressed or dyspnoeic
cat as little as possible) - to calm down

Question 3

with a trauma case what is the inital mangagement plan?

Answer 3

Supplementary oxygen

Staunch any bleeding

Intravenous fluid support

Analgesia

Question 4

how do you perform an orthopeadic exam of a truma cat case?

What features of our patient are we looking for?

How might these findings lead onto a neurological examination?

Answer 4

Let the animal walk-see what it can do and assess grosser neurological
dysfunction

• On which limbs is it unable to weight bear?
• Of these limbs is there gross instability?
• Abnormal posture or limb angulation?
• Are there any skin wounds?
• Can the bone be seen through any skin deficit?

Question 5

What features of a trauma case are we to pay particular attention to
in our neurological examination?

What further test might we employ?

Answer 5

• Mentation/balance
• Spinal reflexes and responses
• Neurological deficits
• Palpable skull or visible jaw fractures such as a displaced mandibular symphysis
• Unstable or painful spine
• Schiff-Sherrington posture
• Flaccid tail - sacrococcygeal luxation ‘pull tail’ - leads to incontinance
• Bladder size/ability to urinate?

Question 6

So under what circumstances should an RTA patient have a chest radiograph or chest ultrasound performed?

Answer 6

always, even if no dysponea - if you don;t do this you will miss things on certain cases

Question 7

If the ultrasound or radiography of a trauma case show a significant pneumothorax what do you do?

Answer 7

drain the chest by needle thoracocentesis.

Question 8

what is a pneumothorax?

Answer 8

rupture to lung (normally at the base of the broncus) the lung leaks air into plural space (normally under slight negative pressure), pressure becomes positive and lungs collapse

Question 9

If the dyspnoea is marked and the animal is struggling to breathe what is appropriate before any imaging is performed?

Answer 9

an exploratory thoracocentesis

Question 10

what is this radiographic view of a cat called?

Answer 10

catogram, assesment of the chest, spine (incl sacroccygeal region), plevis and to an extent urinary tract)

Question 11

what abnormalites can you see here?

Answer 11

the heart is not sitting on the sternum - air present underneath it - pneumothorax
some bleeding into the lung - lung contusions

Question 12

what action is needed with a mild pneumothorax?

Answer 12

if the cats clinical status is stable:
Rest and analgesia maybe all that is required, lung will heal and air will stop leaking out
If condition worsens drain the pneumothorax such that the breathing shows no increased effort

Question 13

are these orthagonal radiographs?

Answer 13

no - they are not at right angles

Question 14

describe this fracture

Answer 14

A simple oblique mid to distal-third diaphyseal fracture of the left humerus

• Simple because it is composed of only two fragments
• Oblique because the fracture surfaces are at angle to one another
• Location speaks for itself- the fracture is described by measuring from the region next to the torso
• Diaphyseal because it involved the central section of the long bone (other regions are the epiphysis and metaphysis)

Question 15

What other factors might we consider with this fracture?

Answer 15

musculospiral groove - the curve of the humerus has a groove within it

Question 16

What structure lies in the musculospiral groove of the humerus?
If this structure were damaged what signs would the cat show?

Answer 16

THE RADIAL NERVE!
If this nerve were damaged the cat would show an inability to extend the carpus and elbow and a lack of sensation to the dorsal aspect of the paw

Question 17

What other neurological abnormalities might you see in a cat with a humeral fracture and significant chest pathology?

Do not forget the neurological aspects of any trauma case

Answer 17

Brachial plexus avulsion - (loss of feeling in the leg) with associated multiple neurological deficits including those of radial nerve damage but also loss of sensation to all aspects of the paw and on occasions Horner’s syndrome. - to make sure that the brachial plexus is intact, squeeze the paw

Horner’s syndrome occurs when there is damage to the sympathetic outflow from the cranial thoracic spine. Signs include miosis, ptosis and pupillary constriction

Question 18

What forces are applied to all bones?
Which of these forces are going to have an effect on this fracture?

Answer 18

axial compression, tension, bending, torsion

Effecting this fracture:
Bending -Yes

Axial compression -Yes
producing shearing in this oblique fracture

Rotation -to an extent
although the large boney spikes will reduce the likelihood of this movement

Tension -No
This is not an avulsion fracture although when the muscles contract they will increase the displacement of the fracture ends

Question 19

What forces is an interlocking nail fracture repair going to protecting against?
Are there any special considerations in this patient?

Answer 19

Not appropriate in this bone-it is not a straight bone (used in tibia and femur)

Question 20

What forces are an IM pin fracture repair going to protecting against?

Answer 20

Bending- good protection afforded

Axial compression-fair support but the oblique nature results in shear which wont be counteracted by a pin that occupies only a proportion of the medullary cavity (what proportion is generally recommended?) so auxiliary fixation is required

Rotation-fair as the fragments are oblique but some rotation will be possible

Avulsion- protection from this force is not required

Question 21

What forces are a plate fracture repair going to protecting against?

Answer 21

Bending- fair protection afforded

Axial compression-good support particularly if one or two of the screws were to compress the oblique fracture (in this case at right angles to the fracture surfaces not along the length of the bone

Rotation-good

Avulsion- protection from this force is not required

Question 22

when considering fracture repair what special considerations do you need to think about

Answer 22

• cat - very light
• Age
• is the fracture is closed (i.e. the skin is intact)

Further questions:
* Is he good natured and likely to respond well to frequent examinations or cage confinement?
* What are the financial circumstances of his owner?
* What are your or the practice’s surgical abilities?
* Do you have the right equipment?

Question 23

what does an IM pin with ancillary fixation mean?

Answer 23

placing an IM pin on a fracture along with something else eg plate

Question 24

what are the issues with using a plate on a humerus?

Answer 24

A plate can be difficult to apply in this location given the curves seen in the humerus.

It requires contouring (shaping) of the plate in several planes.

Exact contouring would not be necessary with a locking plate

The proximity of the radial nerve to the fracture site would also hinder application of the plate and if this were locking then there is no opportunity to angle the screws away from the nerve as their direction is set once locked into the plate

Question 25

We have established that the IM is good for protection against bending but the nature of the fracture means that it is poorer at preventing rotation and shearing.

There is no avulsion component to the fracture
So how can we stop shearing and rotation?

Answer 25

cerclage wire:
This is a wire that surrounds the bone and recreates the bone cylinder.

At least two should be applied to any fracture otherwise a single wire acts as a fulcrum for the fracture to oscillate around.

The fragment edges should be at least twice the width of the bone at the fracture.

If this is the case then the wires will compress the fracture.

They can be applied in several different ways.

By locking the oblique sides of the fracture together the cerclage prevents rotation.

Question 26

what are the problems with cerclage wires?

Answer 26

• Tend to loosen as they are bent over so some surgeons leave them at right angles to the bone resulting in irritation to the soft tissue structures, possible neuropathies and seroma formation under the skin.
• They may reduce the periosteal blood flow to the fracture
• They tend to loosen with time

Question 27

what is a seroma?

Answer 27

build up of fluid (where tissue has been removed)

Question 28

when placing just an external fixator how many pins need to be placed?

Answer 28

As a sole means of fixation at least 3 pins should be placed above and below the fracture.

Question 29

external fixators are usefull for highly comminuted fractures when reconstruction using a plate or other means of fixation is impossible what are the important fetures of these cases?

Answer 29

1) maintain limb length
2) align the joint surfaces
3) avoid interfering with the fracture to encourage bone healing (biological fixation)

Question 30

why are external fixators helpful for open fractures?

Answer 30

the repair avoids the fracture site

Question 31

what has this repair protected the farcture from regarding forces?

Answer 31

Protected the fracture repair from bending with the IM pin

Protected the fracture from axial compression/shear and rotation by the application of three cerclage wires

Increased protection against axial compression and rotation by the the application of a two pin external fixator tied into the IM pin with epoxyresin

Question 32

how do you mangade a fracture repair post-op?
what are you going to disscuss with the owner?

Answer 32

Restrict to the house to protect Biscuit and the fixator.

Discuss possible complications including: failure to heal (non-union), pin loosening and discharge from the pin tracts, and infection around the pin site especially that in the proximal humerus.

The need for frequent re-examinations, follow up radiographs and surgery to remove the fixator.

As well as oral communication, clear written instructions to be given to Biscuit’s owner.

Biscuit is to be examined at three days, a week later and then every one to two weeks depending upon his progress and the presence of complications

Question 33

Radiographs were taken 6 weeks post repair

Has the fracture healed?

What radiographic signs are we looking for to determine healing?

Answer 33

The fracture was determined to have healed and the construct was staged down i.e. the external fixator was removed and IM pin cut down to below the skin surface and left in place.
The eagle eyed amongst you may have noticed that the previous set of pictures of the tied in fixator showed the loss of the fracture line and smooth periosteal new bone over the fracture site…this was the radiograph taken prior to the external fixator removal! The small amount of callus suggests a very stable fracture repair. These are the signs to look for to determine fracture healing as well as the cat’s clinical picture. i.e. how well is it using the limb

Question 34

what do you do when a fracture is healed and the animal has an external fixator?

Answer 34

The IM pin could have been removed but offered continued protection of the fracture from bending. It can remain in the patient permanently. just trim pin so it sits under the skin

On removal of the external fixator pins no attempt is made to close the wounds. These heal by second intention.

Increased restriction is employed after removal of the fixator as the fracture is less well supported now and the bone has to take up the stress originally taken by the fixator.

Biscuit was seen again after a week to examine the pin tracts and assess his limb function.

Question 35

what is wolff’s law?

Answer 35

bone in a healthy person or animal will adapt to the loads under which it is placed.
If loading on a particular bone increases, the bone will remodel itself over time to become stronger to resist that sort of loading.

when taking off an external fixator, the bone will now have more weight and strain going through it so the bone will remodel and this means the animal needs to rest to allow this bone to strengthen and adapt