| TITANIUM NITRIDE CERAMIC FILM AGAINST POLYETHYLENE. A 48 MILLION CYCLE WEAR TEST |
MICHAEL J. PAPPAS, Ph.D*, FREDERICK F. BUECHEL, SR., M.D.**,
GEORGE MAKRIS, MS*
ABSTRACT
Wear is
a major late complication of total joint arthroplasty, particularly
for younger, active patients. Many patients could produce
> 40 million motion cycles after joint replacement. Based
on current experience and testing, typical joint prostheses
are likely to wear out, and need revision in such patients.
One problem is degradation of the metal (counterface) surface.
A harder, more abrasion resistant, counterface surface is
needed.
This study
evaluated the long-term wear of the titanium nitride ceramic
film against ultra high molecular weight polyethylene. In
this test, 4 47-mm femoral cups with a polished 8-micron-thick
titanium nitride coating were run against 4-mm-thick metal-backed
polyethylene bearings machined from GUR415 extruded rod in
water at 37 degrees C at 5 Hz and a 2200-N fluctuating load.
Wear of the counterface and bearing were extremely low.
The average
maximum reduction in thickness of the polyethylene was <
0.02 mm, and < 2 microns in the ceramic film. The average
polyethylene wear rate was only approximately 2% of that found
in a similar test using 32-mm cobalt chromium femoral heads.
The titanium nitride-polyethylene couple has great potential
as a lifetime bearing combination.
Department
of Mechanical Engineering, New Jersey Institute of Technology,
Newark, NJ
** South Mountain Orthopaedic Associates, South Orange, NJ.
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