Principles of open reduction and internal fixation Flashcards
Goal of ORIF
1-restore functional anatomic relationships
2-acheive stable fixation
3-preserve blood supply to the bone and soft tissue
4-allow early and safe mobilization
fracture repair is a balancing act between…
enough and too much stability and how fast a bone heals and how soon a chosen implant will fail
fracture repair biology
trauma sustained results indisruption of endosteal and periosteal blood supply. maintaining an adequate blood supply is essential for healing
four classic stages of bone healing
inflammation, soft callus, hard callus, and remodeling
Biologic Fixation
attempts fixation with minimal violation of the fracture envelope and maximum preservation of soft tissue and blood supply to the fracture site. (open but do not touch)
Anatomic fixation
perfectly reconstruct the bone through reduction, rigid fixation and compression across a fracture promoting primary bone healing.
Requires excessive dissection and disruption of the soft tissue and blood supply to the fracture site
compression forces
force directed along long axis of the bone. If not neutralized, results in axial shortening of the bone
bending force
force focused at a specific point on the bone (ie the fracture site) If not neutralized, results in sharp angulation of the bone at the fracture site
torsion force
a twisting force along long axis of the bone. If not neutralized results in rotation of the fracture fragments
shear force
force directed parallel to the plane of the fracture (ie compression along and oblique fracture). If not neutralized, results in fracture fragments sliding against each other
tension forces
forces applied to bone via forceful muscular shortening (ie avulsion fractures). If not neutralized results in distraction of the bone prominence and contracture of the muscle involved.
Kirschner wires
small gauge, smooth or theaded, trocar or chisel tipped pins that are used primarily as provisional implants)
most commonly used in conjunction with other implants but may be the sole means of fixation for small fragments or epiphyseal/metaphyseal fractures
capable of counteracting BENDING and ROTATIONAL forces (if used in multiples)
Steinmann pins
larger gauge smooth or threaded, trocar or chisel tipped pins.
typically use smooth steinmann pins for IM pinning while threaded pins are used for external fixators
Counteract against BENDING
IM pins
if sole implant for couteracting bending the pin should fill greater than 70% of the diameter of the medullary cavity at its narrowest point
If pin is an adjunct impland for bending then it should fill 30-40% medullary cavity
NEVER use as sole means of fixation because weak when it comes to rotation and compression
bones that IM pin can be used in
any bone with safe access point to medullary cavity including humerus, ulna, femur, tibia.
NEVER PIN A RADIUS
NEVER PIN THRU ARTICULAR SURFACE