Internal fixation #1 Flashcards
Big advantage of internal fixation is?
attached directly to bone and so provides more rigid stabilization than external coaptation
Fractures for which internal fixation is better than than external coaptation (5)
open fracture fractures of the femur humerus and pelvis articular fractures obliqueor comminuted fractures fractures with tension
intramedullary pins control what force well?
bending
Are IM pins often used alone?
No
4 advantages of IM pins
Availability
Axial alignment
Bending control
minimal blood supply disruption
What is cyclic fatigue?
Think of how you break a paper clip
4 disadvantages of IM pins
only control bending
anatomic repair required
Potential injury to surrounding structures
Not good in any flat or curvy bones
Which bone should never ever ever ever be pinned?
Radius
How does an IM pin cause potential injury to surrounding tissues?
Usually atleast one end is sticking out to some extent into the soft tissue
2 ways to place an IM pin?
Normograde
Retrograde
Describe normograde placement of an IM pin?
Line up fracture fragments and then run the pin down from one end to the other
tibial fractures
Describe retrograde placement
Start by placing the pin the proximal fragment via the fracture site, put it all the way until just the tip is in the fracture site then reduce and alignt he fracture and push it down intot he distal fragment
Advantage to retrograde placement?
Cant miss medullary cavity
Disadvantages to retrograde placement?
Surgical approach at fracture site needed
In the tibia the proximal side of the pin will come out into a joint so it is not an option
Disadvantages to retrograde placement?
Surgical approach at fracture site needed
In the tibia the proximal side of the pin will come out into a joint so it is not an option
How big should the diameter of the pin be? What about when combined with a bone plate?
60%of the medullary canal
50% of medullary canal
Should the IM pin penetrate the diatal fragment cortex?
NO there is invariable a joint there
Cross pinning crosses what?
two cortices as well as the fracture line
When is cross pinning approriate
Repairing physeal or very distal/proximal fractures
What forces does cross pinning neutralize?
bending, torsion and compression
When can wiring techniques be useful? (4)
Prevent propogation of fissures
reconstruct fragments to aid in reduction
hold things in place temporarily
Help an IM pin control torsional or compressive forces
When should full cerclage be used?
Long oblique fractures
What constitutes a long oblique fracture?
length of fracture is > than 2 times the diameter of the bone
Why do we always place cerclage wires in groups of 2
because one acts a fulcrum to concentrate forces on the fracture line
What is interfragmentary wiring
Placing wires between 2 fragments to connect them
What are 3 wiring techniques
Full cerclage
interfragmentary wiring
tension band wiring
Tension band wiring is done to counteract what forces/
Tension
Describe tension band wirring?
2 small pins perpendicular tot he fracture line
a figure 8 of wire is then passed through a hole distal to the fracture and the apparatus is looped over those 2 pins and tightend to turn the bad tension into good tension
What is an interlocking nail
Psecially designed rod that is fixed in place with bolts that pass through the rod itself and back through the cortex of the bone
forces controlled by interlocking nails
bending
compression
torsion
aaaand prevents the nail from migrating like in IM pinning
BIg advantage of interlocking nails?
Do not have to remove
Can fix comminuted fractures without anatomic reconstruction of the bone
What is the limitation of an interlocking nail?
need a bone protrusion proximally or distally to avoid going therough a joint
What is the limitation of an interlocking nail?
need a bone protrusion proximally or distally to avoid going therough a joint
Advantage of pin plate combination?
Drop diameter of the pin also only the most distal and most proximal screws for the plate have to do both cortices the rest can do 1
