Unit 5: Upper Limb Joint Replacement Flashcards
Which upper limb joints may be replaced?
shoulder
elbow
wrist
finger
After pain-relief, what does upper limb replacement aim to achieve?
restoration of hand function
What conditions do patients undergoing upper limb replacement suffer from?
rheumatoid arthritis osteoarthritis osteonecrosis post-traumatic arthritis fracture
In what order are spine, upper limb and lower limb replacements carried out in a patient with rheumatoid arthritis?
spine and lower limb before upper limb
Why are spinal surgeries prioritised over upper limb in a patient with rheumatoid arthritis?
cervical spine instability may damage the spine and cause neurological symptoms
Why are lower limb replacements prioritised over upper limb in a patient with rheumatoid arthritis?
it lessens the need for upper body to support the body weight which may compromise survival of an upper limb replacement
If several joints in the upper limb are diseased, how is priority given?
most painful
distal to proximal
Why are the distal joints restored first in the upper limb?
to restore hand function
distal joints may compromise proximal joint rehab
more functional improvement
Why do some surgeons prioritise shoulder over elbow replacement ?
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
What materials are upper limb replacements made from?
stainless steel titanium and titanium alloys cobalt chrome alloys vitallium alloy HDP
What material is used to fixate upper limb replacements?
PMMA bone cement
Which type of shoulder replacement gives worse results?
hemi-arthroplasty
In what order do upper limb replacements last?
shoulder is best
elbow
wrist + fingers are worst
What material works well in flexible hand and wrist replacements?
silicone elastomer
Can a general orthopaedic surgeon perform upper limb replacement? why?
no
small dimensions + complex
Why does a non-specialist orthopaedic surgeon struggle with shoulder replacement?
balancing soft-tissue and inadequate scapula bone stock
List the three categories of shoulder prosthesis that are based on movement constraint and give an example of each
unconstrained eg neer
semiconstrained eg gristina
constrained eg michael reese
What is the stability of an unconstrained shoulder replacement dependent on?
intact, functional rotator cuff
What material is used to construct the glenoid component of a Neer type shoulder prosthesis
polyethylene
Why is it important not to remove soft-tissue attachments when fitting a shoulder joint replacement?
they provide stability
How could an unconstrained design be converted to a semi- constrained design
addition of a hooded glenoid component
What are the disadvantages of a semiconstrained design compared to an unconstrained design?
limited motion means that a greater force is transmitted to the bone-cement interface of the glenoid component which can cause it to loosen
What does a hooded glenoid component do?
resists the upward shear force when elevating the arm to prevent subluxation ( if weak rotator cuff) and avoid tearing supraspinatus tendon
What design is predominantly used for constrained total shoulder replacements?
ball in socket
What is unusual about the Trispherical total shoulder replacement?
it has three balls instead of one
Why is glenoid component fixation important?
as the scapula has a small amount of bone so it is hard to fix to it
What type of glenoid fixation does the Neer prosthesis have?
keel
Do unconstrained or constrained designs need more elaborate glenoid fixation? Why?
constrained due to larger loads
In a total shoulder arthroplasty is the humeral or glenoid component more likely to loosen ?
the glenoid component
What is the function of the shoulder joint?
to position the hand in space
If someone has good rotator cuff function which shoulder replacement would be appropriate?
unconstrained
If someone has poor rotator cuff function which shoulder replacement would be appropriate?
constrained
Name the 3 synovial joints of the shoulder
the glenohumeral, the acromio- clavicular, and the sternoclavicular
Name the other articulation of the shoulder
scapulothoracic bone-on-muscle-on-bone articulation
What is the most important articulation of the shoulder?
glenohumeral
What bony feature of the glenohumeral joint is important in determining its range of motion and stability?
shallow glenoid fossa gives good ROM but low stability
What are the 2 primary aims of an elbow prosthesis?
to relieve pain and provide stability
What are 3 functions of the elbow?
position hand
allow forearm to act as lever
can be weight-bearing
What are the 3 articulations of the elbow?
humeroradial
humeroulnar
proximal radioulnar
What is the most important articulation of the elbow for supporting the load?
humeroulnar
In full extension, what is the angle of the forearm?
10-15 degrees valgus
What 2 things provide elbow stability?
- congruent joint surface
2. soft tissues
Which soft tissues are particularly important for elbow stability?
anterior joint capsule
medial collateral ligament (50% of joint stability in flexion)
lateral collateral ligament
Which structure is loaded if the radial head is removed?
medial collateral ligament
What relevance does a stiff shoulder have to the prosthetic replacement of the elbow?
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.
What are the two main problems with uniaxial hinged elbow prostheses?
loosening and loss of bone stock.
Why do uniaxial hinged elbow prostheses loosen?
fixed coronal plane means that there are excessive shearing forces at the bone-cement interface
In the early metal-on-metal hinged elbow prosthesis designed by Dee, what was a contributory factor to loosening?
The high amount of metal wear debris from the metal-on-metal articulations was also a contributory factor to loosening.
How do semiconstrained elbow prostheses differ from the first generation of hinged elbow prostheses?
they have “sloppy” hinges with varying degrees of side-to-side laxity
When would a semiconstrained elbow prosthesis be used over an unconstrained elbow prosthesis?
soft tissue insufficiency or loss of bone stock
What is an unconstrained elbow prosthesis?
resurfaces the lower end of humerus and ulnar articulating surface
What is required for an unconstrained elbow prosthesis?
intact collateral ligaments for stability
Does semicostrained or unconstrained have higher rates of
a) dislocation?
b) loosening?
a) unconstrained
b) semiconstrained
What benefit may be gained from resurfacing the radial head?
additional load-transmission stability can be
gained.
What are the two types of wrist joint replacement?
flexible hinge
total wrist
What procedure is preferred, if disease only affects the radiocarpal joint?
arthrodesis
What is the function of the distal radio-ulnar joint?
pronation/supination
Which wrist movement is most important?
extension
Where does the axis of rotation of wrist pass through ?
capitate
How does the radiocarpal joint contribute to wrist motion?
large ROM during flexion/extension
stability during abduction/adduction
Which property of the radiocarpal joint can prosthesis not replicate?
stability during abduction/adduction as it is a condyloid joint replaces with a ball-in-socket
What is a flexible hinge prosthesis used in combination with?
resection arthroplasty
Describe a flexible hinge prosthesis
proximal and distal stem with a barrel-shaped misdsection, slides in and out of medullary canal of radius and 3rd metacarpal
What is a flexible hinge prosthesis made of?
silicone elastomer
What percentage of flexible wrist prostheses have been found to tear on the sharp bony edges of the medullary canal?
20%
Which design feature prevents flexible wrist prostheses from tearing?
titanium bone liners (grommits)
What are the two main types of total wrist replacement?
Meuli and Voltz
What design is the meuli total wrist?
ball and socket with 2 pronged distal and radial pronged
What prevents rotatory motion in the meuli total wrist?
soft tissue balance
Which normal wrist articulation does the Voltz prosthesis resemble?
radiocarpal joint: increased abduction/adduction
What components make up the voltz total wrist?
single stem metacarpal component
polyethylene cup
single stem radial component
What are the main problems associated with total wrist prosthesis?
loosening and stress-shielding of the distal radius.
Which hand joint is most frequently replaced?
MCP
What are the two types of MCP replacement?
flexible hinge
total
What are the main indications for MCP replacement?
pain and deformity due to RA
impaired function due to soft tissue imbalance
What MCP procedure would be carried out in a younger patient requiring a strong pinch?
arthrodesis
What type of joint is the MCP?
condyloid
What hand movement is the MCP important for?
80% of finger flexion
How is a flexible hinge MCP replacement stabilised?
new capsuloligamentous sttructure forms
Why is it beneficial to have a sliding flexible hinge MCP replacement ?
even force transmission
increased ROM
How are the grommets, used with flexible hinge prostheses, fixed in position?
press fit
Is flexible hinge or total MCP replacement more successful?
flexible hinge but this may not be suitable for a younger patient who has greater requirements
List the three problems associated with total MCP replacements.
implant fracture, implant migration, implant loosening.
What are the main indications for interphalangeal joint replacement?
pain and deformity associated with rheumatoid arthritis, degenerative arthritis and post-traumatic arthritis
Is arthrodesis or implant arthroplasty a more reliable procedure in the interphalangeal joints?
arthrodesis as the joint contributes little to the overall motion
What type of joints are the interphalangeal?
bicondyloid between proximal and distal phalanx
What stabilises the interphalangeal joints?
bony articulation itself and the surrounding soft tissues (joint capsule, collateral ligaments, the fibrocartilaginous palmar plate and muscle tendons).
Functionally which is the most important interphalangeal joint?
proximal as it has 85% overall motion
Which implant arthroplasty has satisfactory results in the interphalangeal joints?
flexible hinge
