Internal fixation: pins, wires and interlocking nails Flashcards Preview

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Flashcards in Internal fixation: pins, wires and interlocking nails Deck (37):
1

When is internal fixation warranted?

when external coaptation can't be use or has distinct disadvantages

2

What bones should internal fixation always be used?

humerus and femur

3

What kind of fractures should usually be fixed by internal fixation?

1. oblique
2. comminuted

4

What do intramedullar pins control?

bending. but need help for controlling others

5

What do interlocking nails, external skeletal fixators and bone plates control?

all the forces that act on the fracture if the correct hardware/configuration is used

6

What is internal fixation?

fracture repair by means of hardware that attaches directly to the bone

7

What are fractures for which internal fixation is much better than external coaptation?

1. open fractures
2. fractures of femur, humerus, pelvis
3. articular fractures--perfect reduction--early joint movement
4. oblique or comminuted fractures--control commpresion
5. fractures in which primary force acting is tension--olecranon, calcaneus, greater trochanter

8

What forces to intramedullar pins control?

bending

9

What is an intramedullary pin

a rod that stabilizes broken bone by passing longitudinally within medullary canal, v/ close to neutral axis

10

what is a K-wire

A small pin

11

What are 4 advantages of intramedullary pins

1. availability
2. axial alignment
3. bending control
4. minimal to moderate blood supply disruption

12

What are 4 advantages of intramedullary pins

1. availability
2. axial alignment
3. bending control
4. minimal to moderate blood supply disruption

13

What are 4 disadvantages of intramedullary pins?

1. pins control only bending
2. can't always anatomically repair comminuted fractures
3. potential for injury to surrounding structures--sciatic nerve
4. not good for skull, pelvis. RADIUS

14

What are two ways to place an IM pin

1. normograde placement-
2. retrograde placement

15

What is normograde placement?

reduction of fracture then pin run down middle--for tibia, often ulna, humerus

16

What is retrograde placement?

pin inserted in the proximal fragment, then pull out proximal end. --easier to get in canal. NOT tibia. usually in femor

17

What is retrograde placement?

pin inserted in the proximal fragment, then pull out proximal end. --easier to get in canal. NOT tibia. usually in femor

18

What should the diameter of an IM pin be?

60% the diameter of the medullary canal at skinniest point of the bone--still allows blood supply UNLESS combined with bone plate or external fixation (50% then)

19

How should the IM pin be positioned?

run the length of the bone and spear the cortex at the bottom but do not penetrate it

20

What is cross-pinning?

NOT Im pins. The pins are placed so they cross the fracture line and two cortices

21

What are forces neutralized by cross pins?

1. torsion
2. compression
3. moderate bending

22

When is cross pinning appropriate?

for repairing physeal or very distal/proximal metaphyseal fractures

23

What are wiring techniques used for?

1. prevent propagation of fissues
2. reconstruct fragments
3. hold fracture in reduction until definitive repair
4. help control torsion and compressive along with IM pin

24

What is a full cerclage?

the passing wire around the circumference of bone to stabilize a fracture

25

What is the only appropriate use of full cerclage?

for use in long oblique fractures. the cylinder of bone must be reconstructed! and must be TIGHT

26

Why must full cerclage wires be tight?

because if they wiggle they distrupt blood supply to the fracture --thus MUST be perpendicular to bone and not on tapering areas unless anchored

27

What is interfragmentary wiring?

placing wires through two bone fragments to connect them

28

Where can interfragmentary wiring be used?

transverse, short and long oblique fractures. can also use with cross pins/skewer pins

29

Where can interfragmentary wiring be used?

transverse, short and long oblique fractures. can also use with cross pins/skewer pins

30

What is tension band wiring?

It is wiring to counteract tensile force. it transforms bad tensile forces into good compressive forces. Parallel pins are placed perpendicular to the fracture line. A figure of 8 wire is passed through a distal hole and around the pins and tightened

31

What is an interlocking nail?

a rode placed in the medullary canal and fixed in place with scews or bolts that pass from the outside of the bone, through holes in rod and back through cortex
usually left in place

32

What forces do interlocking nails control?

1. bending!
2. compression (scews)
3. torsion (screws)

33

What are the advantages of interlocking nail?

1. can fix comminuted fractures without requiring anatomic reconstruction
2. less disruptive than plate placement so only moderately disrupts blood supply
3. cheaper than bone plate

34

What are the limitations of interlocking nail?

1. need a bone protrusion to introduce into the bone: femur, humerus, tibia NOT RADIUS
2. require a box of special equipment
3. big learning curve

35

What is an IM ESF tie-in

leave IM pin protruding. pass transfixation pin and external fixating bar (tie-in)
IM, external skeletal fixator

36

What is a plate-pin combination?

have a pin AND a bone plate
gives superior bending control--can also drop IM pin diameter to 50% and only need 1 screw per fragment going all the way across

37

What is a plate-pin combination?

have a pin AND a bone plate
gives superior bending control--can also drop IM pin diameter to 50% and only need 1 screw per fragment going all the way across. For the skinny diaphyseal parts just need to go into one cortex