Internal Fracture Fixation: IM Pin and Cerclage Wire Flashcards
(27 cards)
advantages of IM pins
- affordable inventory
- simple application
popular choice
4 forces
- bending
- axial compression + shear
- torsion
- tension
what are the limitations of IM pin and wire fixations?
- limited fracture scenarios
- requires rapid healing
- provides limited stability
- prone to complications
- technical errors, case selection errors
what % of canal fill do we aim for with IM pins?
60-70% medullary canal filled
as long as not past this %, general health of bone is good
what fixations can resist compression?
- ESF
- IM Pin + ESF
- ILN: interlocking nail
- bone plate and screws
what forces can IM pins resist vs not resist?
CAN resist bending!
CANT resist compression/shear, rotation, tension
what fixations can resist rotation?
- IM pin + cerclage wire
- IM pin + ESF
- ILN
- bone plate + screws
what are common additions to IM pins?
- cerclage wire: bone must be perfectly reconstructed ie it doesn’t look broken anymore
- external fixator: “tied in” ie pin out on one end of bone
- plate + screws
what are IM pins made of?
316L stainless steel
what common terminology can you hear regarding IM pins
- steinmann pins: larger
- kirschner wires: “K wires” - small steinmann pins
what does cerclage mean
to encircle or wrap in a bundle
what effect is cerclage wire applying?
interfragmentary compression
what fracture configurations can be good candidates for cerclage wiring? (remember: needs to be able to be perfectly reconstructed)
- long oblique
- single large oblique butterfly
- long spiral
basically just think of LONG OBLIQUE
T/F: if applied the whole way around the bone, cerclage wire can be the sole method of fixation
FALSE: cerclage wire is NEVER used as the sole method of fixation!
how does cerclage wire affect the vascular supply?
- tight, small diameter wires do NOT impede blood supply
- loose wire devascularizes and disrupts callus formation: enough micromotion to interfere with vascularization. also a loose wire just isn’t doing that job
what defines something as a long oblique fracture?
when the fracture line length is AT LEAST 2x the diameter of the bone!!
what happens if you try to use cerclage wire on a comminuted fracture?
collapse and wire loosening
what are the rules for cerclage wiring?
- perfect reconstruction needed
- need AT LEAST 2 WIRES !!
- spaced 1/2 bone diameter apart from the edge of the fracture. if they’re right next to each other; won’t be effective
what is the “weakest link” of circlage wiring?
the way it is secured- by twisting. there are multiple ways to secure the wire but the most common is to just twist it
want a nice even twist, and leave 3 twists and then cut
how do you ensure that the wire has a proper twist?
- firm traction during application
- watch the wire closely to make sure it’s even
what are the rules for IM pin + cerclage wire application?
- PERFECT anatomic reconstruction
- only LONG OBLIQUE/spiral configuration
- properly spaced wires
- > 2 cerclage wires
- no loose wires!!
- do NOT entrap soft tissues
- IM pin 60-70% canal diameter
what bone is not commonly repaired using IM pins? why?
radius- sandwiched top and bottom with joints, so not good access
contrasting to the femur: which has one side of the bone not in the joint
what are variants of cerclage wiring?
- cerclage + K wire: used when the bone is conical shaped: the wire might just slide right off so trap it with a K wire
- hemicerclage: holes drilled through the bone and the wire goes thru the bone. mechanically inferior
- intra-fragmentary: maxillary fractures
what is hemicerclage?
cerclage variant where holes are drilled thru the bone and wire goes thru the holes
mechanically inferior, can damage bone or affect IM pin placement
