Biomedical Engineering Reference
In-Depth Information
Table 16.1
Summary of Multidirectional, Bovine Serum-Lubricated Pin-on-Disc Testing Conditions
Performed on Medical Grade PEEK Articulations
Protein
Concentration
(g/l)
Pin
Diameter
(mm)
Test
Frequency
(Hz)
Test
Duration
(10
6
Cycles)
Maximum
Load (N)
Contact
Stress (MPa)
References
[15,16]
15
5
40
2
1
2
[49]
15
5
40
2
1
2e5
80
a
1
a
2
a
[48]
12
9.5
1
a
Additional tests of a longer duration were also performed at higher loads.
cyclic motions (and/or the load) are typically cycled
at a rate of 1 Hz. The choice of lubricant is especially
crucial. For a biotribology experiment, the pin and
plate are contained in an environmental chamber,
containing a diluted bovine serum lubricant bath,
maintained at body temperature (37
C) (
Fig. 16.7
).
Wear tests conducted under dry conditions or in
a saline water bath are not considered clinically
relevant. Because the wear results are often highly
sensitive to the conditions of testing, it is important to
appreciate the methodological details associated with
a particular set of wear testing results.
In this section, we compare the wear behavior of
PEEK biomaterials documented in four recent
experiments using clinically relevant, multidirec-
tional loading conditions. These studies evaluated
PEEK biomaterials rubbing against metallic coun-
terfaces
[16]
, PEEK biomaterials articulating against
ceramic counterfaces
[15]
, and all-polymer PEEK
biomaterials articulating against themselves
[48,49]
.
The test conditions for these experiments are
comparable and summarized in
Table 16.1
; the wear
factors for the various PEEK articulations are
summarized in
Table 16.2
and
Fig. 16.8
.
Table 16.2
Summary of Wear Factor Results (Mean, Range) for Medical Grade PEEK-OPTIMA LT1
Articulations with CoCr Alloys and Ceramic
Wear Factor (10
L6
mm
3
/N m)
Pin Material
Plate Material
References
CFR-PEEK pitch
HC CoCr
[16]
0.123 (0.0785e0.162)
Biolox Forte
a
CFR-PEEK pitch
[15]
0.134 (0.119e0.148)
CFR-PEEK PAN
LC CoCr
[16]
0.144 (0.0403e0.685)
Biolox Delta
b
CFR-PEEK PAN
[15]
0.165 (0.137e0.182)
CFR-PEEK PAN
HC CoCr
[16]
0.176 (0.0325e0.4)
Biolox Forte
a
CFR-PEEK PAN
[15]
0.194 (0.126e0.238)
CFR-PEEK pitch
Biolox Delta
[15]
0.216 (0.098e0.335)
PEEK
LC CoCr
[16]
7.37 (4.83e8.60)
LC CoCr, low carbon cobalt chromium alloy; HC CoCr, high carbon cobalt chromium alloy; CFR, carbon fiber reinforced; PAN,
polyacrylonitrile fibers; pitch, pitch fibers.
a
Medical grade alumina ceramic.
b
Medical grade zirconia-toughened alumina nanocomposite ceramic.
