Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Fracture Repair 1 > External Skeletal Fixator (ESF) Systems > Flashcards

External Skeletal Fixator (ESF) Systems Flashcards

1
Q

What are the 3 types of ESF?

A

Linear
Circular
Hybrid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does an ESF comprise of?

A

External fixators comprise pins driven into the bone, which are then secured to a side-bar, typically via a metal clamp.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Circular (ring) fixators are composed of A) wires placed under B) rather than pins, which are secured to C) interconnected via connecting rods

A

A) small-diameter
B) tension
C) rings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where are circular ESF particularly useful

A

in periarticular locations where bone stock for implant placement is limited.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why are circular ESF good for angular limb deformities, limb lengthening and bone defects?

A

They can be adjusted with hinged components and motors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What principle is used when used ESF for angular limb deformities, limb lengthening and bone defects?

A

Distraction osteogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do hybrid fixators combine? (2)

A

Circular and linear fixator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where are hybrid fixators useful?

A

Periarticular #

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The post-operative adjustments can be made easily with hybrid ESF but they should be avoided when?

A

In animals with long recovery times

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Advantages of external skeletal fixators over internal fixation techniques (8)

A
  • Stabilisation can be performed in a closed fashion, not disturbing the fracture site.
  • Particularly useful for comminuted fractures where reconstruction of the fracture site is not feasible (or desirable).
  • Fixation away from the fracture site makes them suited to the management of open and contaminated fractures.
  • Very versatile and therefore practical in regions of irregular contour (e.g. hock, mandible).
  • Adjustability allows peri- and post-operative alterations to be made to limb alignment.
  • Construct stiffness can be varied as fracture healing progresses.
  • Removal of implants routine and easy to perform (under sedation or short general anaesthesia).
  • All equipment is removed following fracture healing reducing the risk of subsequent infection.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Can you think of any disadvantages of external skeletal fixators over internal fixation techniques? (4)

A
  • Frequent pin tract discharge and infection at skin-pin/wire interface, which can lead to failure of the pin–bone interface, with subsequent implant loosening.
  • Management of the skin–pin/wire interface required for the duration of time that the frame is in place.
  • Requires patient and client compliance.
  • Accurate mechanical planning of ESF configuration essential to avoid complications.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the different pin types that can be used with ESF? (3)

A

Smooth
Negative profile pin
Positive profile pin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What did smooth pins rely on to prevent pull out?

A

Pin-bone interface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which pins have thread located at the end of the pin? (2)

A

Half pin
End threaded pins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which pins have thread located at the centre of the pin? (2)

A

Full pin
Centrally threaded pins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why were threaded pins created?

A

Increase holding power of pins in bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How are negative profile pins manufactured?

A

By cutting a thread into the shaft of a smooth pin. They have an abrupt end between the threaded and non-threaded regions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Where is there a breakage point in negative profile pins?

A

They have an abrupt end between the threaded and non-threaded regions, which acts as a stress riser predisposing them for breakage at this point.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What type of profile pin is an Elllis pin?

A

Negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where does the Ellis pin engage?

A

Only the trans-cortex of the bone with the thread terminating in the medullary canal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why do positive profile pins have no focal site of stress?

A

Uniform core diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What thread types do positive profile pins (2)

A

Cancellous
Cortical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the pitch and depth of a cancellous thread cf to a cortical thread?

A

Pitch - Greater
Threat - Deeper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Which bone types do cancellous positive profile pins work well in and why?

A

Metaphyseal - Maximise pin-bone interfaces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Cancellous positive profile pins should not be used in what bone type?

A

In cortical bone as these tend to result in micro-cracking

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Which positive profile thread TENDS to be used in dogs/cats?

A

Cortical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the disadvantage of positive profile pins?

A

Threaded portion has a wider diameter than the shaft of the pin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is recommended pin sze?

A

20-30% of bone diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is bending stiffness proportional to?

A

Pin radius to the power of 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What happens to the bending stiffness of a positive profile pin compared to a negative of the same diameter in terms of bending stiffness?

A

Reduced bending stiffness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Which pin eliminates the stress concentration associated with standard negative-threaded pins?

A

The Imex Duraface pin features a gradually tapering negative-threaded region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Which ESF clamp is commonly used?

A

Imex SK clamp

33
Q

What are the sizes of Imex SK clamp?

A

Mini
Small
Large

34
Q

How is the fixation pin secured with a imex SK clamp?

A

Bolt and clamp washer

35
Q

What engages the clamp body with pins + imex SK slamp?

A

Tooth edges

36
Q

What improves stiffness with Imex SK clamps?

A

Designed to use appropriate diameter connecting rods

37
Q

How many pieces does the imex SK clamp body have?

A

2

38
Q

What materials do connecting rods come in? (3)

A

Titanium
Alluminum
Carbon fibre

39
Q

What are the advantages of used aluminum and carbon fibre rods?

A

Radiolucent - good for post op x ray

40
Q

What was the predecessor to the SK system?

A

Kirscher-Ehmer

41
Q

Disadvantages of Kirschner ehmer system? (6)

A
  • Does not allow insertion of positive-profile pins through the clamps.
  • The inability to add additional pins and clamps to the construct without complete disassembly.
  • Weak connecting rods
  • Inability to drill pilot holes
  • Cannot place multiple full pins in a consistent transverse plane
  • Impaired post op radiographs
42
Q

KE plus was created to allow the placement of +vr profile pins through the clamps. What was developed to allow addition of pins without disassembly?

A

Split clamps

43
Q

Negative of split clamps cf to standard single clamps?

A

Lower security

44
Q

With free form ESF, what can be employed to increase adhesion? (2)

A
  • Roughened shaft pins
  • Additional wire
45
Q

What size acrylic column has been shown to be equivalent or superior to a standard small (3.2 mm) KE connecting bar?

A

9.5mm

46
Q

What size column was equivalent to a 4.8 mm medium KE connecting bar?

A

16

47
Q

Advantages of acrylic fixators? (4)

A
  • Ability to place pins at any angle or in any plane:
  • Take maximum advantage of ‘safe corridors’
  • Enable contouring to challenging locations (e.g. mandible).
  • Low-cost.
48
Q

Disadvantages of the acrylic fixators (4)

A
  • Inability to modify the construct once the acrylic has set without removal of acrylic frame.
  • Potential difficulty of maintaining fracture reduction during the curing process.
  • Downstaging of the construct is difficult.
  • Polymerisation of acrylates is an exothermic reaction, which generates heat (place connection bar at least 10 mm from the pin–bone interface).
49
Q

What can rings be made from? (3)

A

Alluminium
Stainless steel
Carbon fibre

50
Q

What do mini rings with elongated holes allow for?

A

Greater flexibility in placement of connecting bolts in smaller patients

51
Q

What are the 2 types of fixation elements used in circular fixators?

A

K wires
Oliver wires

52
Q

How many fixation wires per ring?

A

2

53
Q

How are the fixation wires positioned with with ring?

A

As close to perpendicular as poss

54
Q

The position of fixation wires enables the wires to be placed close together within the A) of the bone, and the B) angle prevents translation of the bone along the wires.

A

A) axis
B) diverging

55
Q

Fixation wires:

It is important to consider the soft tissues and in some situations it is not possible to place the wires A) to each other. B) can also be prevented by using olive wires placed from C) sides of the bone. This is useful in situations that demand D) of the pins at an acute angle relative to one another.

A

A) Perpendicular
B) Translation
C) Opposite
D) Placement

56
Q

What are olive wires?

A

K wires having a stopper in their centre designed to contact the bone

57
Q

As wires are tensioned, what can olive wires do? (2)

A

Compress fissure lines or bone fragments

58
Q

What is the level of fixation wire tensioning dependant on? (2)

A
  • Patient size
  • Ring size
59
Q

What ring size with a small patient does not need tensioning?

A

<50mm

60
Q

Why are partial rings prone to deformation with excess tension?

A

Weaker than full rings

61
Q

Fixation elements are connected to rings using?

A

Wire clamps and bolts fitted through the holes in the rings

62
Q

Rings are interconnected using threaded connection rods, which are then fixed in position with..?

A

Nuts

63
Q

Spherical washers may be used to allow up to what degree of angulation of the connecting rods?

A

10°

64
Q

What allowed creation of articulated frames?

A

Hinges

65
Q

Motor elements are also available to allow the progressive alteration of frame length, used most commonly when? (2)

A

ALD
Limb lengthening

66
Q

Additional posts can be added to provide an additional point of fixation, and what allow the addition of a linear external fixator frame to create a hybrid circular-linear fixator?

A

end-threaded connection rods

67
Q

How are frames classified?

A

According to their use of full and half-pins along with their planar geometry.

68
Q

What is a unilateral ESF?

A

Half pins

69
Q

What is a bilateral ESF?

A

Full pins

70
Q

What is type Ia ESF?

A

Unilateral uniplaner

71
Q

What is type Ib ESF?

A

Unilateral biplaner

72
Q

What is type IIa ESF?

A

All full pins
bilateral (uniplanar)

73
Q

What is a type IIb ESF?

A

Combo - full and half pins
bilateral (uniplanar)

74
Q

What is type III ESF?

A

Addition of a type I frame to a bilateral construct result in a bilateral biplanar

75
Q

How many pins with ESF?

A

6 (3 in each # segment)

76
Q

What is the result of Changing the frame type from a type Ia to a Ib, or I to II or II to III?

A

Increase stiffness

77
Q

What will result in an increase in stiffness of an external fixator frame?
- Removing an additional connecting bar.
- Decreasing the distance between the skin and the connecting bar.
- Decreasing the number of pins in each major segment up to a maximum of four.
- Decreasing the diameter of the transosseous pins.

A
  • Decreasing the distance between the skin and the connecting bar.
78
Q

Why are type III ESF rarely needed these days?

A

More recent developments in clamp design have led to improved stability of simpler constructs.

79
Q

What is the possible downside of ESF type III increased stability?

A

Detrimental to # healing

Fracture Repair 1 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions