Brainscape's Knowledge GenomeTM

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


See full index

AY BMSc Implant Technology > Unit 5b: Elbow Joint Replacement > Flashcards

Unit 5b: Elbow Joint Replacement Flashcards

1
Q

What are the primary and secondary indications for elective replacement of the elbow joint?

A 
Primary = pain relief 
Secondary = restoration of stability
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What condition to most patients for elective elbow replacement suffer from?

A

Rheumatoid arthritis

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

What are the primary functions of the elbow?

A

Allow positioning of the hand in space

Allow the forearm to act as a lever

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

What are the 3 articulations of the elbow?

A

Humeroulnar (trochleo-ulnar)
Humeroradial (radiocapitellar)
Proximal radioulnar

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

What magnitude of loads are carried by the elbow in dynamic activities?

A

As high as 6x body weight

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

Which articulation carries the major part of the load at the elbow?

A

Humeroulnar articulation

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

What is the angulation of the forearm in relation to the upper arm in full extension?

A

10 - 15 degrees of valgus angulation

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

What is the angulation of the forearm in relation to the upper arm at full flexion?

A

A few dgrees of valgus or varus angulation

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

Why do uniaxial hinge prostheses give rise to excessive shearing forces at the bone-cement interface?

A

As coronal plane angle between the upper arm and forearm is not fixed but varies

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

How may degrees of flexion does a normal elbow joint allow?

A

140 degrees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What range of flexion is needed at the elbow for normal daily activities?

A

30 - 130 degrees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the normal range of pronation and supination of the forearm?

A

70 pronation

80 supination

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

What range of pronation and supination is needed for most activities of daily living?

A

50 pronation

50 supination

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

What structures are important in stability of the elbow joint?

A

Anterior capsule

Medial and lateral collateral ligaments

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

Which structure is most important for stability in flexion?

A

Medial collateral ligament

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

What effect does removal of the radial head have on stability mechanisms in the elbow?

A

Medial collateral must resist all valgus loads entirely

17
Q

Why is shoulder replacement given priority over elbow replacements?

A

If patient with total elbow replacement and a stiff shoulder joint attempts internal or external rotation of the arm shoulder stiffness will increase the rotational stresses at the bone-cement interface of the elbow replacement

18
Q

What is the basic design of first generation total elbow prostheses?

A

Single axis hinges (also called “constrained” or “hinged”)

19
Q

Example of 3 first generation prostheses

A

Dee
McKee
Stanmore

20
Q

What were the 3 cobalt chrome parts of the Dee prosthesis?

A

Humeral component
Ulnar component
(Both curved tofit the medullary cavities of the humerus and ulna)
Axis pin

21
Q

What was the range of motion of the Dee prosthesis?

A

0 - 150 degrees of flexion (though not always achieved)

22
Q

How was the Dee prosthesis fixated?prosthesis

A

PMMA bone cement with additional keying points using metal buttons at the base of the humeral stem and undersurface of the ulnar platform

23
Q

What caused long term loosening of the Dee and other first generation prostheses?

A

The restricted single-axis motion forced upon the elbow by the prosthesis - unnatural motion causes excessive shearing forces at the bone-cement interface

Metal wear debris was also a contributing factor

Loss of bone stock

24
Q

What long term implications does loss of bone stock have?

A

When a prosthesis fails it is extremely difficult to salvage the joint

25
Q

What are the 2 main types of second generation prostheses?

A

Semi-constrained metal-to-polyethylene hinge types

Unconstrained metal-to-polyethylene hinge types

26
Q

What is a recent variation of the two main types of second generation total elbow prostheses?

A

Resurfacing the radial head

27
Q

What are the 3 parts of a semi-constrained elbow joint replacement?

A

Humeral component
Ulnar component
Hinged-like metal-to-polyethylene articulation

28
Q

What are examples of semi-constrained elbow joint replacements?

A

Pritchard-Walker
Coonrad
Tri-Axial

29
Q

Why are semi-constrained elbow replacements sometimes referred to as “sloppy-hinge” prostheses?

A

They are essentially hinge-like in appearance and function but allow varying degrees of side-to-side laxity

30
Q

Describe the Tri-Axial prosthesis

A

Semi-constrained design

Loose fitting metal-to-polyethylene hinged articulation with long humeral and ulnar metal stems

31
Q

In which condition did the Tri-Axial prosthesis prove most successful?

A

Rheumatoid arthritis

32
Q

What is the aim behind unconstrained elbow joint replacements?

A

Resurface the lower end of the humerus and the olecranon to reproduce the anatomical structure

33
Q

To achieve full stability in an unconstrained replacement what must remain intact?

A

Collateral ligaments

34
Q

Name 3 examples of unconstrained elbow replacements

A

Ewald (capitellocondylar)
Kudo
Souter-Strathclyde

35
Q

What makes up the Souter-Strathclyde prosthesis?

A 
Humeral resurfacing (Vitallium) 
Ulnar resurfacing (HDP)
36
Q

How does the unconstrained design compare to the semi-constrained design in terms of outcomes?

A

Rates of dislocation slightly higher than semi-constrained

Rates of aseptic loosening generally lower than semi-constrained

37
Q

What is the theoretical benefits of resurfacing the radial head?

A

Benefits of load-transmission stability that are afforeded by the humeroradial articulation

38
Q

What are the 3 components of the Pritchard elbow replacement?

A

Metal humeral component

Ulnar component (metal stemmed base and polyethylene spacer which replaces the articulating surface of the ulna)

Radial component (metal stemmed base and polyethylene spacer which replaces the articulating surfaces of the radius)

39
Q

What has caused variable results with designs that resurface the radial head?

A

Difficulties in balancing the 3 articulations at the time of operation

AY BMSc Implant Technology (13 decks)

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