Elbow Joint Replacement

Question 1

How are elbow joint replacements generally divided?

Answer 1

First generation

Second generation

Question 2

What is the primary indication for elective replacement of the elbow joint?

Answer 2

Pain relief

Question 3

What coniditon do most elective elbow replacement patients suffer from?

Answer 3

Rheumatoid arthritis

Question 4

What are the primary functions of the elbow?

Answer 4

Allow positioning of the hand in space
Allow the forearm to act as a lever
(For many must also function as weight bearing)

Question 5

What are the 3 articulations of the elbow joint?

Answer 5

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

Question 6

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

Answer 6

Humeroulnar

Question 7

In the anatomical position, what angulation is the forear in relation to the upper arm/

Answer 7

10 to 15 degrees of valgus angulation

Question 8

What are the disadvantages of uniaxial hinge prostheses?

Answer 8

Maintain the same coronal plane angle between the upper arm and forearm - gives rise to excessive shearing forces at the bone cement interface - subsequent loosening

Question 9

How much flexion does the elbow allow?

Answer 9

140 degrees

Question 10

What range of flexion are most activities of daily living carried out at?

Answer 10

30 to 130 degrees of flexion

Question 11

What is the range of pronation and supination of the frarm?

Answer 11

70 pronation

80 supination

Question 12

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

Answer 12

50 pronation

50 supination

Question 13

What provides stability for the elbow joint?

Answer 13

Joint surfaces and soft tissues

Question 14

Which three structures are particularly important in the stability of the elbow joint?

Answer 14

Anterior capsule

Medial and collateral ligaments

Question 15

Which ligament provides over 50% of the joint stability when the elbow is flexed?

Answer 15

Medial collateral ligament

Question 16

How does removal of the radial head affect stability?

Answer 16

Reduces joint congruity - medial collateral ligament must resist valgus loads entirely

Question 17

How does the stiffness of the shoulder joint affect loadings on the elbow?

Answer 17

If stiff shoulder and attempt internal or external rotation the stiffness of the shoulder will increase the rotational stresses at the bone-cement interface (why shoulder should be replaced first

Question 18

What are first generation elbow prostheses also known as?

Answer 18

“Constrained” or “hinged” designs

Question 19

Give 3 examples of first generation elbow prostheses

Answer 19

Dee
McKee
Stanmore

Question 20

Describe the Dee prosthesis

Answer 20

3 CoCr parts (humeral, ulnar and the axis pin)
Axis of rotation at right angles to the long axis
Possible 0 to 150 degrees flexion
Curved stems to fir the medullary cavities
Both stems convex anteriorly
Ulnar stem curved convex laterally (need right and eft sides)
Stems secured with PMMA cement and metal buttons

Question 21

What problems were encountered long with first generation elbow prostheses?

Answer 21

Loosening (due to restricted single-axis motion - shearing forces at the bone-cement interface)
High amount of metal wear debris from the metal-on metal articulations (contributed to loosening
Loss of bone stock

Question 22

What re the two main types of second generation total elbow prostheses?

Answer 22

Semiconstrained metal-to-polyethylene hinge types

Unconstrained metal-to-polyethylene resurface types

Question 23

Examples of semiconstrained prostheses

Answer 23

Pritchard-Walker
Coonrad
Tri-Axial

Question 24

What is the basic design of a semiconstrained elbow joint replacement

Answer 24

Stemmed humeral and ulnar components

Hinged-like metal-to-polyethylene articulation (“sloppy hinge”)

Question 25

Why are semiconstrained more suitable than unconstrained types when there is some soft-tissue insufficiency?

Answer 25

Added stability

Question 26

How much varus and valgus laxity does the tri-axial prosthesis allow?

Answer 26

Around 5 degrees varus

Around 6 degrees valgus

Question 27

What magnitude of load is required to pull apart Tri-Axial prosthesis?

Answer 27

50N (unlikely to happen)

Question 28

What is the principle of unconstrained elbow joint replacements?

Answer 28

Resurface lower end of the humerus and the olecranon - aim to reproduce anatomical structure to achieve normal elbow function and contribute to joint stability

Question 29

Give 3 examples of unconstrained elbow prostheses

Answer 29

Ewald (capitellocondylar)
Kudo
Souter-Strathclyde

Question 30

What are the 2 components of the Souter-Strathclyde prosthesis and what are they made of?

Answer 30

Humeral component - Vitallium

Ulnar component - HDP polyethylene

Question 31

What is the success rate of the Souter-Strathclyde prosthesis?

Answer 31

Around 90% of patients achieve a good or excellent result

Question 32

Examples of radial head resurfacingprostheses

Answer 32

Pritchard

Voltz

Question 33

What are the 3 components of the Pritchard prosthesis

Answer 33

Metal humeral component (Replaces articulating surfaces of the trochlea and capitellum)

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

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

Question 34

Why are polyethylene spacers supplied in various thicknesses?

Answer 34

So surgeons can select the correct size for optimum joint stability

Question 35

Why are the Voltz and modified Capitellocondylar prostheses no longer recommended for use?

Answer 35

Unsatisfactory rates of loosening and dislocation