In vitro wear performance of standard, crosslinked, and vitamin‐E‐blended UHMWPE

Abstract

Crosslinked vitamin-E-stabilized polyethylene acetabular cups were compared with both commercially available conventional and custom-crosslinked polyethylene acetabular cups in terms of wear behavior, in a hip joint simulator for five millions cycles, using bovine calf serum as lubricant. We correlated the wear experiments results with the chemical characterization of the investigated materials: Fourier transformed infrared (FTIR) spectroscopic analyses, differential scanning calorimetry, and crosslink density measurements were used to assess the chemical characteristics of the pristine materials. In addition, further FTIR analyses and cyclohexane extraction were carried out after the simulator experiments. Lipids absorption was observed in all tested specimens and it has been shown to strongly affect the results of the wear test. Corrected gravimetric wear measurements showed that vitamin-E blended, crosslinked polyethylene wore more than the traditional crosslinked polyethylene but exhibited a much lower wear than conventional ultrahigh-molecular weight polyethylene. The chemical analyses showed that the addition of vitamin E reduced the crosslinking efficiency. Given the correlation between crosslink density and wear resistance, this gave an explanation for the observed wear performances.

Edge loading does not increase wear rates of ceramic‐on‐ceramic and metal‐on‐polyethylene articulations

“…In a study by Oral et al 52 in vitro wear of a vitamin E doped HXLPE was tested in very thin liners and found a four-fold to 10-fold decrease in wear rate compared with conventional UHMWPE, respectively, with or without third body particles. In a study by Affatato et al, 53 a slighty increased in vitro wear rate of HXLPE stabilized with vitamin E compared with conventional HXLPE was found. The authors attributed this difference to a decreased crosslinking efficiency due to the blending with trace concentrations of vitamin E prior to the crosslinking process.…”

“…The authors attributed this difference to a decreased crosslinking efficiency due to the blending with trace concentrations of vitamin E prior to the crosslinking process. 53 Crosslink density is well correlated with the wear resistance of UHMWPE. 47 Vitamin E stabilized HXLPE subjected to the same radiation dose as conventional HXLPE has a 10% to 15% lower crosslink density and may therefore have a slightly lower wear resistance.…”

Interplay between surface properties of standard, vitamin E blended and oxidised ultra high molecular weight polyethylene used in total joint replacement and adhesion of Staphylococcus aureus and Escherichia coli

“…1,9,20 In particular, it has been demonstrated that oxidative degradation of UHMWPE gamma-sterilized in air increased its wear while decreasing mechanical strength, constituting the main cause of the dramatic implant failures occurred in the last years. [21][22][23] As a consequence, many efforts have been made to improve UHMWPE quality and performance, for example through the reduction or elimination of the oxidation. The VE stabilization of UHMWPE has been recently proposed to improve oxidation resistance while maintaining wear resistance and fatigue strength.…”

Interplay between surface properties of standard, vitamin E blended and oxidised ultra high molecular weight polyethylene used in total joint replacement and adhesion of Staphylococcus aureus and Escherichia coli

“…The VE stabilization of UHMWPE has been recently proposed to improve oxidation resistance while maintaining wear resistance and fatigue strength. 7,20,23,24 VE, a free radical scavenger and well established biological antioxidant, prevented oxidation and delamination and had a favorable long-term effect on fatigue performance of the UHMWPE, increasing the resistance to fatigue cracks associated with oxidation without negatively altering the biocompatibility of the implant. 20,24 Moreover, it has been shown that VE when added to UHMWPE does not have any cytotoxic effects and acts as an effective anti-inflammatory.…”