Healed
True or false - it takes less time for bone to reach normal strength with stable repair?
False
Where are wires most likely to fatigue and fail? Why?
At the level of the knot, twisting can cause damage
True or false - there is only one type of lag screw?
False - any type of screw can be "lag," only engaging far fragment
What kind of material is used in bone plates?
What long bone is the most difficult to place an interlocking nail in?
Humerus
In what instance is a neutralization implant necessary?
Articular fracture - neutralizes forces being borne by the bone
What are the four types of wire?
Tension band, cerclage, hemicerclage, interfragmentary
What are the biggest differences between cortical and cancellous screws?
Cortical: finer pitch, shallower profile
Cancellous: wider pitcher, larger profile
A plate should be on the _____ side of the bone
Tension
True or false - the use of solid interlocking nails is preferred in small animals as opposed to hollow
True
What is bridging osteosynthesis?
The implants span larger segments of bone, avoid area immediately surrounding fracture
What is the tensile strength of a wire directly related to? Why is this important?
Cross-sectional area - Pi*r2
Small increase in diameter --> exponentially stronger wire
The outer diameter of a screw determines the ____ strength
The inner diameter of a screw determines the ____ strength
The outer diameter of a screw determines the pull-out strength
The inner diameter of a screw determines the bending strength
What is the most common kind of plate we use?
IM pin should fill about ___% of the medullary canal when used in combo with a bone plate?
30-45%
Why is biologic osteosynthesis useful?
Less precise reconstruction and less rigid fixation, which reduces iatrogenic trauma to fracture site, causes early formation of the callus
What are the diameters of Kirschner wires?
0.035, 0.045, 0.062
What is the definition of a glide hole?
Over-drilling near cortex so that screw threads don’t purchase --> way to lag screws
Define bridging implant?
Buttress or bridging implant: carries all the weight and resists forces applied to the bone
What kind of loading do interlocking nails experience? Why is this beneficial over bone plates?
Direct axial compressive loading during weight-bearing when placed on neutral axis of the bone
Bone plates exposed to bending forces - eccentric to neutral axis of the bone
What does AO VET stand for?
Arbeitsgemeinschaft für Osteosynthesefragen Veterinary division of the AO Foundation
At what tension level (in Newtons) is a cerclage wire considered "loose"?
When would a position screw be beneficial over a lag screw?
If compression would cause collapse of bone fragments, such as complex articular fractures
What are the two biggest reasons for scalloped underside of dynamic compression plate?
Decreased bone contact --> reduced amount of cortical bone that has decreased vascularity
Decreased area moment of inertia of the solid section of the plate -->less stress concentration at screw holes
For each ____% increase in canal filling by an IM pin, the plate strain is reduced by ___%
For each 10% increase in canal filling by an IM pin, the plate strain is reduced by 20%