Wear and Osteolysis Flashcards
What are the steps involved in osteolysis d/t wear debris?
1) particulate debris formation
2) macrophage activated osteolysis
3) prosthesis micromotion
4) particulate debris dissemination
What is the most accurate and precise technique to evaluate polyethylene wear?
Radiostereometric analysis; uses radiopaque tantalum beads planted in the bone
What is the most important factor determining the amount of wear particles generated in a THA?
Head size; increased volumetric wear
When comparing conventional polyethylene liners to the newer highly cross-linked polyethylene liners, what is true?
Highly cross-linked poly has reduced wear and number of wear particles, but has inferior mechanical properties
What effect does head size have on wear rates of highly cross-linked poly?
None; wear rates are similar for head sizes 22-46mm
What causes stripe wear in ceramic on ceramic bearings?
Instability related to head lift off during gait
Which type of inflammatory cell is involved in the biological response to metal-on-metal particulate debris?
Lymphocytes
What molecules are associated with macrophage induced osteolysis surrounding orthopaedic implants?
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
Osteoprotegrin (OPG) binds to what structure to inhibit particle-induced osteolysis?
RANKL; OPG binds to RANK-ligand so that it cannot bind to RANK and stimulate osteoclast activation
What urine test is indicative of type 1 collagen breakdown and can be utilized as a marker of bone turnover?
N-telopeptide
What two things are a/w higher metal ion levels in MoM hips?
smaller implant diameter and acetabular cup abduction angle >55 degrees are associated with elevated serum metal ion levels
