Friction and wear - Orthopaedic Biomaterials in Research and Practice - page 275

Delamination

Wear

FIGUre 11.15 (See color insert.) Wear and delamination of an acetab-
ular cup (uhmWPe).

Final remarks Wea r continues to be a challenge in implant surgery. As will be discussed

at greater length in Chapter 14, the biologic response to wear debris may
prove to be a limiting factor in TJR arthroplasty life. Although it will
take very long development periods, new materials and possibly newer
designs offer future hope of performance improvement in this area.

additional problems

PROBLEM 11.3
Refer to Figure 11.16 and observe that TKR A has bearing surfaces that
fit closely, whereas TKR B has a distinctly smaller radius of curvature
for the femoral component than for the tibial component.
Considering the bearing surfaces, select the true statements from the
following:

1. Because type A prostheses allow no entrance for lubricating fluids,
they wear out faster.

2. The bearing contact stress for prosthesis B is greater than that for A .

3. Considering the coefficient of friction between Co-Cr alloys
and UHMWPE, prosthesis A should significantly resist flexion-
extension more than B .

(a) (b)

FIGUre 11.16 tKr profiles (Problem 11.3).