Wear rate and biocompatibility of pre and post UV irradiated UHMWPE for tribo-pair in total knee replacement application

Abstract

Ultra-high molecular weight polyethylene (UHMWPE) and CoCr alloy are popular tribo-pair in total knee replacement. Wear in the liner is a major failure reason for knee implant. Therefore, this work focuses on an approach for reducing the wear rate by irradiating the UHMWPE specimens using Ultraviolet (UV) radiation. The powder of UHMWPE was molded into a plate by microwave-assisted compression (MAC) molding. The UV radiations of intensity 0.025 J/cm2 were irradiated on the MAC molded UHMWPE specimens. The wear rate was determined using a pin on the disc wear tribometer using the pre and post-irradiated UHMWPE specimens as a pin and CoCr alloy as the disc. The pre and post-irradiated UHMWPE sliding was done at the load of 40 N for 1500 m under dry conditions. The reduction in the wear rate recorded was 56% after UV irradiation. The surface morphology of the worn specimens was done using scanning electron microscopy (SEM) and the 3D surface mapping technique. The obtained results of wear rate were validated numerically by implementing the contact problem solution in Archard’s wear law using user-subroutine on Python. The experimental and numerically obtained results were in good agreement. The biological response of pre and post-irradiated specimens was evaluated by hemolysis assay, cellular compatibility against peripheral blood mononuclear cells, platelet adhesion, and in vitro degradation under a simulated blood fluid environment.