Screws and bone plates Flashcards
What is the principle behind bone plate weightbering
increases friction between the bone and the plate
Locking plates don’t only screw into the bone but into the?
Plate
Do locking plates need to be closely contoured tot he bone?
No not as much cause friction comes from screws
Downside to screwplacement with locking plates?
Screws cannot be placed at an angle
What forces are neutralized by plates?
All forces
By themselves screws mostly control?
Torsion, compression, and tension
When do we often use screws?
Half a condyle has broken off, times when bending is not an issue
3 advantages to plate fixation?
Anatomic reconstruction is not necessary
do not require removal
fragments can be conmpressed
3 disadvantages to plate fixation
PLacement requires very large entry
Cant capture small proximal or distal chunks
If infection sets in you need another surgery
Not only are pins great for helping out with bending forces but?
Make reduction for plate placement almost done
If plate pin combo do all the screws need to double cortices?
No only the most proxinmal and distal screws then need to be within bo0th cortices
The minimum number of cortices that must be engaged by a screw in each major fragment with IM pin plate combo is?
3
Screws, size is named based on? the hole you drill for the screw is based on?
Outer diameter
Inner diameter
What is an interfragmentary screw?
Holds things together while you place the plate on
In order for a fracture repair to be stabilised adequately by a non locking plate screws going through the plate must engage how many cortices per majore fragment?
6
How can you still drill a screw across a fracture line in a neutral fashion?
Squeeze them together with a clamp or they will push apart
How can you still drill a screw across a fracture line in a neutral fashion?
Squeeze them together with a clamp or they will push apart
Describe what is meant by lagging a screw?
near cortex is overdrill and far cortex is normally drilled
Screw is tightened and it sucks them together
What is screw pitch?
Distance between threads
Variable pitch screws have what effect?
Behaves just like a lag screw
Bone plates are named by?
The size of the screws their holes can accomodate
3 forms of screw accommodation?
Locking
Round hole
Oval holes
3 forms of screw accommodation?
Locking
Round hole
Oval holes
Describe neutralization plate
Holds the fracture fragments in close formation so some axial forces can be borne
Describe a compression plate
fragments are actually squeezed together
Describe a tension band?
If plate is there to counter mostly tensile forces
What is a buttress plate?
weightbering for almost all of the forces
Number of cortices that need to be engaged for a non locking plate in each main fragment?
6
Plates bend far mor easily when they are? Meaning you should do what?
Compressed
If putting them on a bending bone or bone where bending is a concern put them on the side that will stretch
3 fractures that are good to plate?
Diaphyseal fractures that take long to heal
proximal areashard to use ESF on
Animals that wont return
Fractures that are not good to plate
short proximal or distal fragments
involving growth plates
