Electron beam irradiation at doses below 150 kGy is a widely used technique to obtain highly crosslinked
ultra-high-molecular-weight polyethylene (
UHMWPE). Its current use in
total joint replacement components may improve wear resistance and decrease
UHMWPE particle debris. However, currently used post-irradiation thermal treatments, which aim to decrease the
free radicals within the material, introduce microstructural changes that affect
UHMWPE mechanical properties, particularly the
fatigue strength. This influence may be crucial in total knee replacements, where
fatigue-related damage limits the lifespan of the
prosthesis. Therefore, more studies are required to understand
UHMWPE fatigue after current crosslinking protocols. This study was planned to evaluate the influence of
UHMWPE remelting after irradiation on the material
fatigue resistance. The remelting was achieved at 150 degrees C for 2 h on
UHMWPE previously irradiated at 50, 100, and 150 kGy.
Fatigue evaluation included short-term tests under cyclic tensile stress with zero load ratio, R = 0, and 1 Hz. In addition, stress-life testing was performed using 12% yield as the criterion for failure. Near-threshold
fatigue crack propagation experiments were also performed at a frequency of 5 Hz, and crack length was measured in nonthermally treated and remelted irradiated
UHMWPE. Crystallinity percentage was calculated from DSC measurements. The results pointed out that irradiation positively contributed to total life analysis, but the further remelting process decreased the flaw initiation resistance. On the other hand, both processes negatively affected the
fatigue resistance of notched components. From a clinical point of view, the results suggest that the material
fatigue behavior should be carefully studied in new
UHMWPE to avoid changes related to material processing.