Acetabular Component Flashcards Preview

BMSc Semester 2 > Acetabular Component > Flashcards

Flashcards in Acetabular Component Deck (16)
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1
Q

How can wear be reduced?

A

reduce joint loading

keep sliding distance as small as practically possible

find alternative materials for the replacement head that reduce wear in the HDP

2
Q

What ceramic materials are used? Which one is more promising?

A

Alumina and zirconia

Zirconia

3
Q

Why is a small head disadvantageous?

A

rate of depth of wear is greater due to smaller contact area - Range of motion is reduced as the head wears into the cup

There is an increased likelihood of dislocation in the post-op period due to increased chance of neck impingement on the edge of the cup

4
Q

What material normally makes up the acetabular component?

A

HDP

5
Q

How does a metal backing plate assist in stress management?

A

evens stresses and reduces stress concentrations

not found in practice

6
Q

name some important features in acetabular cup design

A

size of femoral head and cup

metal backing plate

thickness of HDP layer

outer dimension of the acetabulum

positioning of the acetabular cup (more centrally)

7
Q

How can cup loosening occur?

A

mechanical over stressing

biological reaction to ingress of HDP particles

8
Q

how does HDP wear cause bone resporption?

A

hip fragments come into contact with bone

tissue reaction to the HDP causes bone resorption

HDP migrates long the interface causing further resorption

9
Q

How does centralisation of the cup help?

A

reduces the moment arm and therefore reduces the hip joint load

10
Q

What disadvantages does centralisation of the cup have?

A

the prosthesis is mounted on softer weaker bone

deepened cup leads to earlier impingement of the femoral neck on the rim of the acetabulum - limiting motion and increasing risk of dislocation as the head is prised from the socket.

11
Q

What is the failure rate before 10 years in hip replacements?

A

10%

12
Q

What happens first in most cases: Loosening or wear out?

A

loosening

13
Q

What is the process of replacing a hip prosthesis called?

A

revision arthroplasty

14
Q

If the revision process is completed in one step what is this called?

A

exchange arthroplasty

15
Q

Why is revision extra difficult to achieve?

A

loss of bone by the osteolytic resorption process

16
Q

What are the complications of revision surgery?

A

high failure rate

wheelchair existence

death from complications of difficult surgery