small animal fracture management workshop Flashcards
When a trauma case comes in, what are the first things you want to examine
ABC (airways, breathing, circulation)
Assess breathing/respiration
Any evidence of blood loss assessed by mucosal colour & pulse volumes
Urinary system - assess integrity of urinary tract - is bladder palpable?
Are there any obvious neurological abnormalities?
Describe the initial management of a trauma case
Establish airway- remove material from mouth & intubate if required
If markedly dyspnoeic - exploratory chest drainage or T FAST/POCUS ultrasound
(Thoracic Focused Assessment with Sonography for Trauma / Point of Care Ultrasound)
Supplementary oxygen if required and as long as it doesn’t distress the cat (oxygen cage?)
Staunch any bleeding
Intravenous fluid support
Analgesia
Cage confinement, rest and observation-handle the distressed or dyspnoeic cat as little as possible
-this is of great importance as cats can easily enter a decompensated state)
What is the first step in an orthopaedic examination and what are you looking for?
Let animal walk - see what it can do & 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?
Is there crepitus on manipulation of limb
Are there any skin wounds?
Can the bone be seen through any skin deficit?
All these findings can be made without touching the cat
After observing a trauma case cat on the floor, what are the next steps of an orthopaedic examination?
Only after initial examination has been completed place cat on examination table
Use minimum restraint. If owner is able to hold cat it will often be calmer
Confirm site of pain, swelling & instability in fracture case & ligament injury
Palpate the pelvis
Examine the mandible and skull
Gently palpate the spine
During orthopaedic examination there maybe evidence of neurological dysfunction in which case a rapid assessment of neurological status is warranted
What features of trauma case are we to pay particular attention to in our neurological examination?
Mentation/balance
Spinal reflexes and responses
Neurological deficits e.g. paretic limb or one lacking cutaneous sensation
- maybe difficult to assess in limb with orthopaedic trauma
Palpable skull or visible jaw fractures such as displaced mandibular symphysis
Unstable or painful spine
Schiff-Sherrington posture- indicative of severe spinal cord injury when animal shows flaccid hindlimbs & increased tone in fore
Flaccid tail
Bladder size/ability to urinate?
In a trauma case of animal with:
not using LF
Neurological exam fine
slightly increased resp rate
What would you do next?
Investigate the reason for his mild dyspnea
Always do radiograph or ultrasound, even if no dyspnoea
If imaging shows significant pneumothorax drain chest by needle thoracocentesis.
If dyspnoea is marked & animal is struggling to breathe exploratory thoracocentesis is appropriate before any imaging is performed
If there is diaphragmatic rupture this will require management prior to fracture repair
In many circumstances in feline patient a “catogram” is useful allowing assessment of chest, spine, including sacrococcygeal region, pelvis &, to an extent, urinary tract but only if cat will tolerate gentle restraint to obtain image
Abnormalities:
- Mild to moderate pneumothorax
- Some lung contusions
Action:
- Much depends upon the cat’s clinical status
- Rest and analgesia may be all that is required
- If condition worsens drain pneumothorax so breathing shows no increased effort
Having stabilised our patient & confirmed no significant internal injuries in Biscuit but that he clearly has a fractured left forelimb
What first aid action might you take?
Orthogonal radiograph
External support with Robert Jones bandage can be used but is only appropriate for fractures below stifle & elbow
External support also reduces pain experienced by animal but may require sedation or even GA to apply
External support can be used in fractures that are in danger of becoming open such as those in radius/ulna & tibia. Open fractures are considerably rarer in upper limb where there is greater muscle coverage
Cats accept external support poorly & cage rest might be more appropriate & was already being employed to manage pneumothorax
Cage rest is also appropriate for minimally displaced relatively stable fractures
Are these views orthogonal and describe the fracture
No
simple oblique mid to distal-third diaphyseal fracture of left humerus
- Simple because its composed of only 2 fragments
- Oblique because fracture surfaces are at angle to one another
- Diaphyseal because it involved central section of long bone (other regions are epiphysis & metaphysis)
Why are orthogonal radiographs important
Could miss fracture if you only took radiograph from 1 view
What other factors might we consider given the position of the fracture within the humerus:
What structure lies in the musculospiral groove of the humerus?
THE RADIAL NERVE!
- If this nerve were damaged cat would show inability to extend carpus & elbow & lack of sensation to dorsal aspect of paw
what other neurological abnormalities might you see in cat with humeral fracture & significant chest pathology?
Brachial plexus avulsion 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.
Horner’s syndrome occurs when there is damage to the sympathetic outflow from the cranial thoracic spine. Signs include miosis, ptosis and pupillary constriction
Describe the potential use of IM pins in this case
Bending- good protection afforded
Axial compression-fair support but oblique nature results in shear which wont be counteracted by pin that occupies only proportion of medullary cavity so auxiliary fixation is required
Rotation-fair as fragments are oblique but some rotation will be possible
Avulsion- protection from this force is not required
Describe the potential use of a plate in this case
Bending- fair protection afforded
Axial compression-good support esp. if 1-2 screws were to compress oblique fracture (in this case at right angles to fracture surfaces not along length of bone)
Rotation-good
Avulsion- protection from this force is not required
plate can be difficult to apply in this location given curves in humerus.
- requires contouring of plate in several planes
Proximity of radial nerve to fracture site would also hinder application of plate & if this were locking then there is no opportunity to angle screws away from nerve as their direction is set once locked into plate
Describe the potential use of interlocking nails in this case
Not appropriate in this bone-not a straight bone & thus rarely would interlocking nail be used in this
location
We have established that IM pin is good for protection against bending but nature of fracture means that it’s poorer at preventing rotation & shearing.
There is no avulsion component to the fracture
So how can we stop shearing and rotation?
The cerclage wire
wire that surrounds bone & recreates bone cylinder in either 2 fragment/comminuted fractures
At least 2 wires applied to any fracture as single wire can act as fulcrum around which fracture will oscillate.
fragment edges should be at least 2x width of bone at fracture & then wires will compress the fracture.
They can be applied in several different ways.
- By locking oblique sides of fracture together cerclage prevents rotation
- by reconstructing column of bone axial compression is neutralised.
What are possible problems or cerclage wire?
Tend to loosen as they are bent over so some surgeons leave them at right angles to bone resulting in irritation to soft tissue structures, possible irritation to adjacent nerves & seroma formation under skin.
They may reduce periosteal blood flow to the fracture
They tend to loosen with time
Given limitations of cerclage wiring it was judged that further protection against axial compression & rotation was required
What other ancillary method of fixation could be employed in this case?
External fixator
Describe the use of an external fixator
can be used as a sole means of fixation or combined with others such as the IM pin
sole means of fixation: 3+ pins placed above & below fracture.
When using external fixator to augment other repairs such as this, single pin above & below fracture is adequate
Useful for highly comminuted fractures when reconstruction using plate or other means of fixation is impossible
In these cases the important features of repair are to:
1) maintain limb length
2) align the joint surfaces
3) avoid interfering with fracture to encourage bone healing (so called biological fixation)
also useful if fracture is open & infected as this repair avoids fracture site & allows local treatments
How does this final repair protect the fracture?
Protects fracture repair from bending with the IM pin
Protects fracture from axial compression/shear & rotation by application of 3 cerclage wires
Increases protection against axial compression & rotation by application of a 2 pin external fixator tied into IM pin with epoxyresin
How would you manage this case post-operatively?
Restrict to the house to protect Biscuit and the fixator.
Discuss possible complications including pin loosening & discharge from pin tracts especially that in 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 were given to Biscuit’s owner.
Radiographs were taken 6 weeks post repair
Has the fracture healed?
What radiographic signs are we looking for to determine healing?
fracture was determined to have healed & construct was staged down (external fixator was removed & IM pin cut down to below skin surface & left in place)
small amount of callus suggests very stable fracture repair. These are signs to look for to determine fracture healing as well as cat’s clinical picture. i.e. how well is it using the limb
Describe the removal of an external fixator
IM pin could be removed but offer continued protection of fracture from bending. It can remain in patient permanently.
On removal of external fixator pins no attempt is made to close the wounds. These heal by second intention.
Increased restriction is employed after removal of fixator as fracture is less well supported now & bone has to take up the strain originally taken by the fixator.
