Adhesion performance of UHMWPE after different surface modification techniques.

A novel design of an ultra-high molecular weight polyethylene (UHMWPE) glenoid component has been proposed, based on adhesion to PMMA bone cement. However, due to the non-polar nature of UHMWPE, surface modification techniques are needed to obtain good adhesion and thus for the design to be viable. The aim of the study is to investigate adhesion of UHMWPE after different surface treatments. Three gas-phase surface modification techniques were investigated, namely UV/Ozone, corona discharge and radio frequency glow discharge plasma, as well as abrasion. The surface treated samples were examined using water contact angle, surface energy and roughness measurements, as well as single lap-joint shear testing using polymethylmethacrylate (PMMA) bone cement and methylmethacrylate (MMA) adhesive. The effect of aging on bonded samples has also been investigated. Corona and glow discharge treatments were found to activate the surface as shown by an increase in surface energy of over 100% in an order of less than a minute, corresponding to an increase in ultimate shear stress from 0.12 to 0.40 MPa. In contrast, UV/Ozone required exposure times in the order of minutes to have an effect that was still incomparable to the other gas-phase treatments examined. Abrasion produced slightly better adhesion properties for single lap-joints bonded with PMMA compared to the corona treatment. The best treatment was found to be a combined treatment of surface roughening for 10 s, and subsequently a 90 s glow discharge treatment, resulting in failure of the UHMWPE sheet material.