principles of small animal fracture repair

Question 1

what are orthogonal radiographs?

Answer 1

radiographs taken at right angle to each other

Question 2

What is a fracture score

Answer 2

A numerical value given to a fracture to determine how difficult a fracture repair will be based on biological and non-biological factors

Question 3

What patient factors affect the fracture score

Answer 3

weight of animal
age
boisterousness and ability to manage cage rest
concurrent illness

Question 4

What fracture factors affect the fracture score

Answer 4

Type of fracture:- does it allow compression plating or require external fixator, etc.
Open or closed?
Associated soft tissue injuries
Single or one of several fractures

Question 5

What owner factors affect fracture score

Answer 5

Will they comply with post-op instructions?
Finances

Question 6

What surgeon factors affect the fracture score

Answer 6

Are they able to manage this fracture?
Is the correct equipment available?

Question 7

what are the normal forces on a long bone due to weight bearing and muscle contraction

Answer 7

bending
torsion
tension
axial compression

Question 8

which side would a plate be applied and why

Answer 8

always applied to the
tension side as it will not be
broken by tensile forces
but will be by successive
compressions

Question 9

What are the tension aspects of the long bones?

Answer 9

Femur :- lateral aspect

Tibia:- medial aspect

Radius:– craniomedial aspect

Humerus:- latero-cranial aspect

Mandible:- the dorsal aspect

Question 10

What is the consequence of axial compression on a fracture

Answer 10

this is good if the fracture is transverse (i.e. at right angles to the long bone) or if the fracture interdigitates. If not then compression of a comminuted (i.e. multiple fragments) or an oblique fracture causes the fracture to collapse or shear

Question 11

What is the consequence of tension on a fracture

Answer 11

Tension produced by ligaments or tendons pulling on one of the bone fragments causes the fracture to be distracted and needs to be overcome with lag screwing or tension bands

Question 12

What is the consequence of torsion on a fracture

Answer 12

Torsion resulting in rotation of the fracture site requires management with plates, external fixator or an interlocking nail

Question 13

What is the consequence of bending on a fracture

Answer 13

Bending occurs due to the asymmetrical nature of the bone loading. A pin in the centre of the medullary cavity is best suited at counteracting this force

Question 14

when does primary bone healing occur and what implants does this require

Answer 14

Primary bone healing requires intimate contact of the bone ends preferably under compression.
This requires application of a bone plate and extensive dissection and manipulation of soft tissues

Question 15

What is strain in bone healing?

Answer 15

change in length over the original length of the fracture
a small gap (length between ends of fractured bones) and much movement => high strain => fracture fails to heal as tissues rupture

Question 16

How does the healing process reduce the strain on a fracture

Answer 16

the fracture becomes progressively stiffer by the formation of granulation tissue, callus and bone
the body resorbs the ends of the fragment to decrease the strain

Question 17

What is the purpose of post-op radiographs for a fracture

Answer 17

to assess:
Alignment of the fracture
The positioning of implants
The encroachment of implants into joints or soft tissues or the bridging of growth plates in young animals

Question 18

In what situations should radiographic assessment be made after a fracture repair?

Answer 18

Prior to the removal of implants
If progression is not as anticipated
There is evidence of sepsis