Wear and Osteolysis

Question 1

What are the steps involved in osteolysis d/t wear debris?

Answer 1

1) particulate debris formation
2) macrophage activated osteolysis
3) prosthesis micromotion
4) particulate debris dissemination

Question 2

What is the most accurate and precise technique to evaluate polyethylene wear?

Answer 2

Radiostereometric analysis; uses radiopaque tantalum beads planted in the bone

Question 3

What is the most important factor determining the amount of wear particles generated in a THA?

Answer 3

Head size; increased volumetric wear

Question 4

When comparing conventional polyethylene liners to the newer highly cross-linked polyethylene liners, what is true?

Answer 4

Highly cross-linked poly has reduced wear and number of wear particles, but has inferior mechanical properties

Question 5

What effect does head size have on wear rates of highly cross-linked poly?

Answer 5

None; wear rates are similar for head sizes 22-46mm

Question 6

What causes stripe wear in ceramic on ceramic bearings?

Answer 6

Instability related to head lift off during gait

Question 7

Which type of inflammatory cell is involved in the biological response to metal-on-metal particulate debris?

Answer 7

Lymphocytes

Question 8

What molecules are associated with macrophage induced osteolysis surrounding orthopaedic implants?

Answer 8

1) TNF- alpha
2) TGF-beta
3) osteoclast activating factor
4) oxide radicals
5) hydrogen peroxide
6) acid phosphatase
7) interleukins (Il-1, IL-6)
8) prostaglandins