Wear and wear particle analysis of UHMWPE with and without Vitamin E. (a) Wear factors for virgin UHMWPE and UHMWPE with 3000 ppm and 30,000 ppm vitamin E against smooth and rough CoCr plates in the six-station and single-station wear rigs, respectively. (b) High-resolution FEGSEM images of UHMWPE particles from (I) virgin UHMWPE showing granule, flake, and agglomerated fibril particle morphologies on the 1 µm filter, size bar 15 µm. (II) Particles from the 3000 ppm vitamin E UHMWPE showing flake and agglomerated fibril morphologies on the 10 µm filter, size bar 60 µm. (III) Nanometer-sized granules from virgin UHMWPE on the 0.015 µm filter, size bar 300 nm. Nanometer-sized granules (IV) from the 3000 ppm VE UHMWPE material, size bar 300 nm.