A simulator study of adverse wear with metal and cement debris contamination in metal-on-metal hip bearings.
OBJECTIVE
Third-body wear is believed to be one trigger for adverse results with metal-on-metal (MOM) bearings. Impingement and subluxation may release metal particles from MOM replacements. We therefore challenged MOM bearings with relevant debris types of cobalt-chrome alloy (CoCr), titanium alloy (Ti6Al4V) and polymethylmethacrylate bone cement (PMMA).


METHODS
Cement flakes (PMMA), CoCr and Ti6Al4V particles (size range 5 µm to 400 µm) were run in a MOM wear simulation. Debris allotments (5 mg) were inserted at ten intervals during the five million cycle (5 Mc) test.


RESULTS
In a clean test phase (0 Mc to 0.8 Mc), lubricants retained their yellow colour. Addition of metal particles at 0.8 Mc turned lubricants black within the first hour of the test and remained so for the duration, while PMMA particles did not change the colour of the lubricant. Rates of wear with PMMA, CoCr and Ti6Al4V debris averaged 0.3 mm(3)/Mc, 4.1 mm(3)/Mc and 6.4 mm(3)/Mc, respectively.


CONCLUSIONS
Metal particles turned simulator lubricants black with rates of wear of MOM bearings an order of magnitude higher than with control PMMA particles. This appeared to model the findings of black, periarticular joint tissues and high CoCr wear in failed MOM replacements. The amount of wear debris produced during a 500 000-cycle interval of gait was 30 to 50 times greater than the weight of triggering particle allotment, indicating that MOM bearings were extremely sensitive to third-body wear. Cite this article: Bone Joint Res 2015;4:29-37.
Loma Linda University, 900 E Washington St, Suite 200, Colton, 92324, California, USA.
T
T
Halim
Loma Linda University, 900 E Washington St, Suite 200, Colton, 92324, California, USA.
I C
IC
Clarke
Loma Linda University, 900 E Washington St, Suite 200, Colton, 92324, California, USA.
M D
MD
Burgett-Moreno
Loma Linda University, 900 E Washington St, Suite 200, Colton, 92324, California, USA.
T K
TK
Donaldson
Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993-0002, USA.
C
C
Savisaar
Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993-0002, USA.
J G
JG
Bowsher
3rd-body abrasion; Hip arthroplasty; metal-on-metal; simulator; wear