Transfer film effects induced by 3D-printed polyether-ether-ketone with excellent tribological properties for joint prosthesis

Based on the building principle of additive manufacturing, printing orientation mainly determines the tribological properties of joint prostheses. In this study, we created a polyether-ether-ketone (PEEK) joint prosthesis using fused filament fabrication and investigated the effects of printing orientation on its tribological properties using a pin-on-plate tribometer in 25% newborn calf serum. An ultrahigh molecular weight polyethylene transfer film is formed on the surface of PEEK due to the mechanical capture of wear debris by the 3D-printed groove morphology, which is significantly impacted by the printing orientation of PEEK. When the printing orientation was parallel to the sliding direction of friction, the number and size of the transfer film increased due to higher steady stress. This transfer film protected the matrix and reduced the friction coefficient and wear rate of friction pairs by 39.13% and 74.33%, respectively. Furthermore, our findings provide a novel perspective regarding the role of printing orientation in designing knee prostheses, facilitating its practical applications.