Unit 5: Upper Limb Joint Replacement

Question 1

Which upper limb joints may be replaced?

Answer 1

shoulder
elbow
wrist
finger

Question 2

After pain-relief, what does upper limb replacement aim to achieve?

Answer 2

restoration of hand function

Question 3

What conditions do patients undergoing upper limb replacement suffer from?

Answer 3

rheumatoid arthritis
osteoarthritis
osteonecrosis
post-traumatic arthritis
fracture

Question 4

In what order are spine, upper limb and lower limb replacements carried out in a patient with rheumatoid arthritis?

Answer 4

spine and lower limb before upper limb

Question 5

Why are spinal surgeries prioritised over upper limb in a patient with rheumatoid arthritis?

Answer 5

cervical spine instability may damage the spine and cause neurological symptoms

Question 6

Why are lower limb replacements prioritised over upper limb in a patient with rheumatoid arthritis?

Answer 6

it lessens the need for upper body to support the body weight which may compromise survival of an upper limb replacement

Question 7

If several joints in the upper limb are diseased, how is priority given?

Answer 7

most painful

distal to proximal

Question 8

Why are the distal joints restored first in the upper limb?

Answer 8

to restore hand function
distal joints may compromise proximal joint rehab
more functional improvement

Question 9

Why do some surgeons prioritise shoulder over elbow replacement ?

Answer 9

shoulder pain radiates to elbow
immobilised shoulder loads elbow which may cause prosthesis to fail
rehab of elbow is easier with a pain-free shoulder

Question 10

What materials are upper limb replacements made from?

Answer 10

stainless steel
titanium and titanium alloys
cobalt chrome alloys
vitallium alloy
HDP

Question 11

What material is used to fixate upper limb replacements?

Answer 11

PMMA bone cement

Question 12

Which type of shoulder replacement gives worse results?

Answer 12

hemi-arthroplasty

Question 13

In what order do upper limb replacements last?

Answer 13

shoulder is best
elbow
wrist + fingers are worst

Question 14

What material works well in flexible hand and wrist replacements?

Answer 14

silicone elastomer

Question 15

Can a general orthopaedic surgeon perform upper limb replacement? why?

Answer 15

no

small dimensions + complex

Question 16

Why does a non-specialist orthopaedic surgeon struggle with shoulder replacement?

Answer 16

balancing soft-tissue and inadequate scapula bone stock

Question 17

List the three categories of shoulder prosthesis that are based on movement constraint and give an example of each

Answer 17

unconstrained eg neer
semiconstrained eg gristina
constrained eg michael reese

Question 18

What is the stability of an unconstrained shoulder replacement dependent on?

Answer 18

intact, functional rotator cuff

Question 19

What material is used to construct the glenoid component of a Neer type shoulder prosthesis

Answer 19

polyethylene

Question 20

Why is it important not to remove soft-tissue attachments when fitting a shoulder joint replacement?

Answer 20

they provide stability

Question 21

How could an unconstrained design be converted to a semi- constrained design

Answer 21

addition of a hooded glenoid component

Question 22

What are the disadvantages of a semiconstrained design compared to an unconstrained design?

Answer 22

limited motion means that a greater force is transmitted to the bone-cement interface of the glenoid component which can cause it to loosen

Question 23

What does a hooded glenoid component do?

Answer 23

resists the upward shear force when elevating the arm to prevent subluxation ( if weak rotator cuff) and avoid tearing supraspinatus tendon

Question 24

What design is predominantly used for constrained total shoulder replacements?

Answer 24

ball in socket

Question 25

What is unusual about the Trispherical total shoulder replacement?

Answer 25

it has three balls instead of one

Question 26

Why is glenoid component fixation important?

Answer 26

as the scapula has a small amount of bone so it is hard to fix to it

Question 27

What type of glenoid fixation does the Neer prosthesis have?

Answer 27

keel

Question 28

Do unconstrained or constrained designs need more elaborate glenoid fixation? Why?

Answer 28

constrained due to larger loads

Question 29

In a total shoulder arthroplasty is the humeral or glenoid component more likely to loosen ?

Answer 29

the glenoid component

Question 30

What is the function of the shoulder joint?

Answer 30

to position the hand in space

Question 31

If someone has good rotator cuff function which shoulder replacement would be appropriate?

Answer 31

unconstrained

Question 32

If someone has poor rotator cuff function which shoulder replacement would be appropriate?

Answer 32

constrained

Question 33

Name the 3 synovial joints of the shoulder

Answer 33

the glenohumeral, the acromio- clavicular, and the sternoclavicular

Question 34

Name the other articulation of the shoulder

Answer 34

scapulothoracic bone-on-muscle-on-bone articulation

Question 35

What is the most important articulation of the shoulder?

Answer 35

glenohumeral

Question 36

What bony feature of the glenohumeral joint is important in determining its range of motion and stability?

Answer 36

shallow glenoid fossa gives good ROM but low stability

Question 37

What are the 2 primary aims of an elbow prosthesis?

Answer 37

to relieve pain and provide stability

Question 38

What are 3 functions of the elbow?

Answer 38

position hand allow forearm to act as lever can be weight-bearing

Question 39

What are the 3 articulations of the elbow?

Answer 39

humeroradial humeroulnar proximal radioulnar

Question 40

What is the most important articulation of the elbow for supporting the load?

Answer 40

humeroulnar

Question 41

In full extension, what is the angle of the forearm?

Answer 41

10-15 degrees valgus

Question 42

What 2 things provide elbow stability?

Answer 42

1. congruent joint surface | 2. soft tissues

Question 43

Which soft tissues are particularly important for elbow stability?

Answer 43

anterior joint capsule medial collateral ligament (50% of joint stability in flexion) lateral collateral ligament

Question 44

Which structure is loaded if the radial head is removed?

Answer 44

medial collateral ligament

Question 45

What relevance does a stiff shoulder have to the prosthetic replacement of the elbow?

Answer 45

A stiff shoulder increases the loads placed on the bone-cement interface of a prosthetic replacement of the elbow when the patient internally or externally rotates their upper arm. Ultimately this may cause the prosthesis to loosen.

Question 46

What are the two main problems with uniaxial hinged elbow prostheses?

Answer 46

loosening and loss of bone stock.

Question 47

Why do uniaxial hinged elbow prostheses loosen?

Answer 47

fixed coronal plane means that there are excessive shearing forces at the bone-cement interface

Question 48

In the early metal-on-metal hinged elbow prosthesis designed by Dee, what was a contributory factor to loosening?

Answer 48

The high amount of metal wear debris from the metal-on-metal articulations was also a contributory factor to loosening.

Question 49

How do semiconstrained elbow prostheses differ from the first generation of hinged elbow prostheses?

Answer 49

they have "sloppy" hinges with varying degrees of side-to-side laxity

Question 50

When would a semiconstrained elbow prosthesis be used over an unconstrained elbow prosthesis?

Answer 50

soft tissue insufficiency or loss of bone stock

Question 51

What is an unconstrained elbow prosthesis?

Answer 51

resurfaces the lower end of humerus and ulnar articulating surface

Question 52

What is required for an unconstrained elbow prosthesis?

Answer 52

intact collateral ligaments for stability

Question 53

Does semicostrained or unconstrained have higher rates of a) dislocation? b) loosening?

Answer 53

a) unconstrained | b) semiconstrained

Question 54

What benefit may be gained from resurfacing the radial head?

Answer 54

additional load-transmission stability can be | gained.

Question 55

What are the two types of wrist joint replacement?

Answer 55

flexible hinge | total wrist

Question 56

What procedure is preferred, if disease only affects the radiocarpal joint?

Answer 56

arthrodesis

Question 57

What is the function of the distal radio-ulnar joint?

Answer 57

pronation/supination

Question 58

Which wrist movement is most important?

Answer 58

extension

Question 59

Where does the axis of rotation of wrist pass through ?

Answer 59

capitate

Question 60

How does the radiocarpal joint contribute to wrist motion?

Answer 60

large ROM during flexion/extension | stability during abduction/adduction

Question 61

Which property of the radiocarpal joint can prosthesis not replicate?

Answer 61

stability during abduction/adduction as it is a condyloid joint replaces with a ball-in-socket

Question 62

What is a flexible hinge prosthesis used in combination with?

Answer 62

resection arthroplasty

Question 63

Describe a flexible hinge prosthesis

Answer 63

proximal and distal stem with a barrel-shaped misdsection, slides in and out of medullary canal of radius and 3rd metacarpal

Question 64

What is a flexible hinge prosthesis made of?

Answer 64

silicone elastomer

Question 65

What percentage of flexible wrist prostheses have been found to tear on the sharp bony edges of the medullary canal?

Answer 65

20%

Question 66

Which design feature prevents flexible wrist prostheses from tearing?

Answer 66

titanium bone liners (grommits)

Question 67

What are the two main types of total wrist replacement?

Answer 67

Meuli and Voltz

Question 68

What design is the meuli total wrist?

Answer 68

ball and socket with 2 pronged distal and radial pronged

Question 69

What prevents rotatory motion in the meuli total wrist?

Answer 69

soft tissue balance

Question 70

Which normal wrist articulation does the Voltz prosthesis resemble?

Answer 70

radiocarpal joint: increased abduction/adduction

Question 71

What components make up the voltz total wrist?

Answer 71

single stem metacarpal component polyethylene cup single stem radial component

Question 72

What are the main problems associated with total wrist prosthesis?

Answer 72

loosening and stress-shielding of the distal radius.

Question 73

Which hand joint is most frequently replaced?

Answer 73

MCP

Question 74

What are the two types of MCP replacement?

Answer 74

flexible hinge | total

Question 75

What are the main indications for MCP replacement?

Answer 75

pain and deformity due to RA | impaired function due to soft tissue imbalance

Question 76

What MCP procedure would be carried out in a younger patient requiring a strong pinch?

Answer 76

arthrodesis

Question 77

What type of joint is the MCP?

Answer 77

condyloid

Question 78

What hand movement is the MCP important for?

Answer 78

80% of finger flexion

Question 79

How is a flexible hinge MCP replacement stabilised?

Answer 79

new capsuloligamentous sttructure forms

Question 80

Why is it beneficial to have a sliding flexible hinge MCP replacement ?

Answer 80

even force transmission | increased ROM

Question 81

How are the grommets, used with flexible hinge prostheses, fixed in position?

Answer 81

press fit

Question 82

Is flexible hinge or total MCP replacement more successful?

Answer 82

flexible hinge but this may not be suitable for a younger patient who has greater requirements

Question 83

List the three problems associated with total MCP replacements.

Answer 83

implant fracture, implant migration, implant loosening.

Question 84

What are the main indications for interphalangeal joint replacement?

Answer 84

pain and deformity associated with rheumatoid arthritis, degenerative arthritis and post-traumatic arthritis

Question 85

Is arthrodesis or implant arthroplasty a more reliable procedure in the interphalangeal joints?

Answer 85

arthrodesis as the joint contributes little to the overall motion

Question 86

What type of joints are the interphalangeal?

Answer 86

bicondyloid between proximal and distal phalanx

Question 87

What stabilises the interphalangeal joints?

Answer 87

bony articulation itself and the surrounding soft tissues (joint capsule, collateral ligaments, the fibrocartilaginous palmar plate and muscle tendons).

Question 88

Functionally which is the most important interphalangeal joint?

Answer 88

proximal as it has 85% overall motion

Question 89

Which implant arthroplasty has satisfactory results in the interphalangeal joints?

Answer 89

flexible hinge