Effect of electron beam irradiation on load-displacement responses of UHMWPE

Abstract

Ultra-High Molecular Weight Polyethylene (UHMWPE) has been used successfully for articulating surfaces of joint endoprostheses, i.e. cup linear on acetabular component of total hip arthroplasty, in orthopaedics for over three decades. Although numerous attempts have been performed to characterize and to improve the polymeric material, i.e. to reduce the molecular degradation due to in vivo oxidation, the effect of electron beam irradiation on loaddisplacement characteristics of UHMWPE has not been reported clearly. The aim of the current study is to quantify the effect of the electron beam irradiation with alteration of the amount of irradiation on the mechanical characteristics of the polymeric material. In this work, monotonic uniaxial and small punch tests were conducted to examine the relative capabilities of four samples irradiated with electron beam at 0, 50, 100, and 150 kGy, based on a prediction of mechanical behavior of the UHMWPE materials. Load-displacement behaviors of UHMWPE were not changed significantly by electron beam irradiation less than 150 kGy although the stiffness of irradiated UHMWPE decreased gradually. Conclusively, changes of stiffness and deflection by irradiation were not significant. However, load characteristics were significantly changed by irradiation.