Abstracts Posters SICOT-SOF meeting Gothenburg 2010 _2_

Poster
Topic: General Orthopaedics
Abstract number: 25060
SURFACE CROSSLINKED UHMWPE WITH SUPERIOR STRENGTH AND
FATIGUE RESISTANCE
Orhun MURATOGLU, Ebru ORAL, Bassem GHALI, Shannon ROWELL
Massachusetts General Hospital, Boston (UNITED STATES)
Fracture risk of highly cross-linked ultrahigh molecular weight polyethylene
(UHMWPE) joint implants due to low fatigue strength is a concern in high stress
applications. We hypothesized that limiting cross-linking to the articular surface would
improve mechanical properties without sacrificing wear resistance. Surface
crosslinking was achieved by using vitamin E-containing UHMWPE such that the
articular surface was depleted of the antioxidant and the bulk contained a higher
concentration, allowing for higher surface cross-linking after irradiation due to vitamin
E hindering crosslinking with increasing concentration. GUR1050 UHMWPE was
blended with vitamin E at 0.05 wt% and 0.5 wt%. Blended UHMWPE with a gradient
in vitamin E concentration was made by either layered compression molding of the
two blends. The UHMWPEs were irradiated to 150 kGy and tested along with the
control UHMWPE (irradiated and melted).Surface crosslinked UHMWPE had a wear
rate comparable to that of control. The fatigue strength was 30% higher than the
control. The impact strength (87±1 kJ/m2) was also comparable to unextracted,
irradiated control (89±1 kJ/m2). These results corroborated that the bulk mechanical
properties of surface crosslinked UHMWPE were not affected by the surface
crosslinking. The fatigue and IZOD impact strength was 66% and 45% higher than
that of 100-kGy irradiated and melted UHMWPE, respectively. Surface crosslinked
UHMWPE has combined wear and fatigue resistance superior to current technology
and we envision that it will improve the performance of UHMWPE implants in high
stress conditions such as the use of thin acetabular liners, total knees and
resurfacing implants.
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