Lecture 25 - Fracture Mechanics Flashcards
What is a Type I Salter fracture?
Straight across
What is a Type II Salter fracture?
Above
What is a Type III Salter fracture?
Lower or beLow
What is a Type IV Salter fracture?
Two
OR
Through
What is a Type V Salter fracture?
ERasure of the growth plate
OR
cRush
What are the 5 components used to describe a fracture?
- Open or Closed
- Configuration (transverse, short oblique, long onlique, comminuted)
- Location of the fracture within the bone
- Specific bone fractured
- Displacement and overriding
What are the types of implants (materials) used in fracture repair?
316 LVM Stainless Steel
Titanium Pure
Stiffness of a rod is _____.
radius to 4th power
Stiffness of a square beam is _____.
height to 3rd power
width to 1st power
Stiffness of a length of with beam is _____.
length to 3rd power
To use cerclage wire, fracture must be _____.
Long oblique
T/F: Cerclage wire can be used as the sole means of repair.
False
What size cerclage wire should be used in dogs vs. cats/toy breeds?
Dogs = 1-1.2mm (18-20G)
Cats/toy breeds = 0.64-0.81mm (20-22G)
___ or more circumferential cerclage wires must be used, placed _____ apart.
2, 8-10mm
Cerclage should be no closer than ____ from the fracture ends.
5mm
Cerclage wire must reside directly on _____ and confirmed to be _____.
bone, tight
The size of the intramedulary pin should be ___% the diameter of the _____ cavity.
50-75%, medullary
The intramedulary pin should be placed _____ when possible.
normograde
The intramedulary pin should be seated in the _____.
trans (far) epiphysis
The fixation construct of the intramedulary pin should counter _____, or _____ should be employed.
torsional stress, ancillary devices
If intramedulary pins are used in conjunction with plates, the size of the pin should be ____% the diameter of the _____.
30-50%, medullary cavity
The size of the dynamic compression plate used is dictated by the size of the _____ allowed.
screw
The major diameter of the screw used should approach but be no greater than ___% of the diameter of the bone being plated with a dynamic compression plate.
20%
Screws should engage at least ____ cortices on either side of a fracture when using a dynamic compression plate.
6
Screws shoud engage both _____ and _____ cortices when using a dynamic compression plate.
cis (near), trans (far)
When plating with a dynamic compression plate, the fracture should be _____ so that there is cortical-cortical contact (esp on the _____ cortex).
reduced, trans
The dynamic compression plate should be _____ so that it lies directly on the bone.
contoured
In dynamic compression plating, screws should be placed in _____ — away from the fracture line in the _____.
“load position”, dynamic compression hole
The size of the locking plate is dictated by the size of the _____ allowed.
screw
With a locking plate, the major diameter of the screw should approach, but be no greater than ___% of the diameter of the bone being plated.
20%
How many screws should engage bone on either side of a fracture when using a locking plate?
3-4
What type of screw can be used with a locking plate?
unicortical
When using a locking plate, it must not _____, but should be as _____ as possible.
lay directly on the bone, close
When using a locking plate, ancillary devices such as _____ or _____ should be considered.
intramedullary pins, second plates
The size of the external fixator is directed by the size of the _____ allowed.
fixation pin
When using an external fixator, the major diameter of the fixation pin should approach, but be no greater than ___% of the diameter of the bone being plated.
20%
What type of pins should be used with external fixators when possible?
These penetrate both _____.
full pins;
Penetrate both cis and trans cortex
What is an alternative to using full pins with external fixators?
Double connecting rods with half pins
How many pins should engage bone on each side of the fracture when using an external fixator?
3
_____ profile pins should be used and _____ for transfixation pin should be pre-drilled.
Positive, pilot holes
Pins should be placed _____ to the long axis of the bone when possible.
perpendicular
Pins should be placced near the _____ of the bone, as well as _____ to the fracture.
ends, close
What size connecting rods should be used with an external fixator?
large
When using an external fixator, clamps should be placed close to, but not touching the _____.
skin
What types of fractures require lag screws?
long oblique
Lag screws should be placed _____ to a fx line.
Perpendicular
Bone likes _____.
compression
