Natural polyphenol-stabilised highly crosslinked UHMWPE with high mechanical properties and low wear for joint implants.

Radiation crosslinked ultra high molecular weight polyethylene (UHMWPE) with high mechanical strength, wear resistance, and oxidative stability is critical for the long term performance and life span of the joint implants based on crosslinked UHMWPE. The use of antioxidants and/or radical scavengers has proven efficient in stabilising crosslinked UHMWPE against oxidation, whereas challenges remain to explore new methods to offer not only oxidative stability, but also superior wear resistance and mechanical properties in the long term. Herein, two natural polyphenols, gallic acid (GA) and dodecyl gallate (DG), containing three hydroxy groups each, have been demonstrated potent in protecting irradiated UHMWPE against adverse oxidative challenging at elevated temperatures. The presence of these polyphenols does not inhibit the crosslinking in comparison to the high dose-irradiated vitamin E/UHMWPE. The tensile and impact properties of these polyphenol-stabilized highly cross-linked UHMWPE after accelerated ageing in accordance with ASTM F2003 are superior to those of the irradiated and remelted UHMWPE. Pin-on-disc (POD) wear tests of these materials demonstrated low wear compared to that of highly crosslinked and remelted UHMWPE. In vitro culture with chondrocytes showed a slightly improved biocompatibility for these irradiated antioxidant/UHMWPE. These natural polyphenols are potential alternatives for the stabilisation of highly crosslinked UHMWPE for joint arthroplasty.