Principles of open reduction and internal fixation Flashcards

1
Q

Goal of ORIF

A

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

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2
Q

fracture repair is a balancing act between…

A

enough and too much stability and how fast a bone heals and how soon a chosen implant will fail

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3
Q

fracture repair biology

A

trauma sustained results indisruption of endosteal and periosteal blood supply. maintaining an adequate blood supply is essential for healing

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4
Q

four classic stages of bone healing

A

inflammation, soft callus, hard callus, and remodeling

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5
Q

Biologic Fixation

A

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)

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6
Q

Anatomic fixation

A

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

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7
Q

compression forces

A

force directed along long axis of the bone. If not neutralized, results in axial shortening of the bone

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8
Q

bending force

A

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

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9
Q

torsion force

A

a twisting force along long axis of the bone. If not neutralized results in rotation of the fracture fragments

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10
Q

shear force

A

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

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11
Q

tension forces

A

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.

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12
Q

Kirschner wires

A

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)

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13
Q

Steinmann pins

A

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

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14
Q

IM pins

A

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

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15
Q

bones that IM pin can be used in

A

any bone with safe access point to medullary cavity including humerus, ulna, femur, tibia.
NEVER PIN A RADIUS
NEVER PIN THRU ARTICULAR SURFACE

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16
Q

orthopedic wire

A

stainless steel, monofilament of varying size and can be used as an adjunct device.

17
Q

methods of orthopedic wire placement

A

cerclage, hemi-cerclage, tension band, interfragmentary wire.
most common uses are cerclage and tension band

18
Q

Cerclage wire

A

used to encircle bone to hold fragments together

very little resistance to bending

19
Q

rules of cerclage wire

A

1-fracture should be simple (2-3 pieces), long oblique
2-fracture must be anatomically reduced
3-minimum of 2 wires
4-space wires 1 cm apart and at least 0.5cm from fracture end
5- avoid soft tissue entrapment
6-must be tight
7- place perpendicular to the long axis of the bone
8-wire should be 18g or 20g in diameter
9-using twist cerclage: leave 3 twists to secure the wire and apply twist under tension
NEVER USE AS SOLE MEANS OF FIXATION

20
Q

Interlocking nails

A

use the bending strength of an IM pin and add the ability to neutralize in compression and torsion
can be used on humerus, femur and tibia (require enough bone stock proximally and distally to accomodate the bolts)
Mid-diaphyseal fractures work best

21
Q

screws

A

rarely used without bone plate

can be used alone or in conjunction with other implants

22
Q

four parts of screw

A

Head=top of screw
Shaft=core and diameter determines the size of drill bit used to place screw
Thread=inclined plane wrapped around shaft responsible for engaging bone
Tip=rounded(require tapping) or fluted(self tapping)

23
Q

Interfragmentary screws

A

used in isolation are placed as lag screws to compress two fragments together or as positional screws to hold two fragments in a neutral relationship

24
Q

screw as primary means against shear

A

screw diameter should be larger (40-50%) compared to the bone fragment

25
Q

screws used in conjunction with a plate

A

should have a diameter 25-30% the diameter of the diaphysis

26
Q

Plates

A

placed as neutralization plates, compression plates, or bridging(buttress) plates

27
Q

neutralization plating is used

A

when needed to neutralize axial forces across a fracture in order to protect interfragmentary fixation
i.e the fracture is reduced using lag screws and a neutralization plate is used to span bone, protecting lag screws

28
Q

compression plate

A

used when anatomic reduction and interfragmentary compression are acheiveable and the desired goal of absolute stability to allow primary bone healing

29
Q

bridging/buttress plate

A

used for comminuted, unstable fractures for which anatomic restoration and absolute stability are not possible
plate is used to attach two main bone fragments ,provide length, axial alignment and rotation.

30
Q

where should bone plates be placed

A

when possible plates should be placed on the tension surface of the bone
this allows us to take advantage of the tension band effect which converts tension forces to compressive forces at the fracture site

31
Q

plating on compression surface

A

only when necessary

resistance to bending is significantly compromised

32
Q

Dynamic compression plate(DCP)/limited contact dynamic compression plate

A

used in neutral, compression or bridging designed with an oval hole to allow for neutral or eccentric placement of the screw

33
Q

eccentric screw head placement

A

results in plate shifting in relation to the bone

34
Q

limited contact dynamic compression plates

A

differ from dynamic compression plates by their scalloped design which theoretically allows for preservation of periosteal vascularity and improved cortical profusion.

35
Q

Locking compression plate

A

accepts conventional and locking screws
allows screws and plate to become one construct (internal fixator)
less reliant on perfect contouring

36
Q

String of pearl plate

A

locking system designed to be used with cortical screws
screw threads engage the plate nodes
SOPs can be contoursed with six degrees of freedom

37
Q

veterinary cuttable plates

A

thin, lightweight plates

close inter-hole distance useful with shorter fragments, can stack plates and customize length

38
Q

Principles of bone plating

A

1-minimum of 6 cortices per segment (conventional/plate alone)
2-minimum of for cortices per segment (locking plate/plate+ rod)
3-screws at least 5mm from fracture (1.5x diameter of screw)
4-avoid penetrating fracture site
5-avoid penetrating or crossing open physis
6-avoid penetrating articular surfaces
7-plate should be perfectly contoured (if not locking) to avoid displacement of fragments