Plasma engineered surfaces for orthopedic devices

Atmospheric pressure plasma was used to graft various biocompatible polymers to the surface of ultra-high molecular weight polyethylene (UHMWPE). Polymers used as grafts in this study were poly(2-hydroxyethylmethacrylate) (PHEMA) and polyethylene glycol (PEG). A significant decrease in contact angle was noted for grafted surfaces, indicating increased hydrophilicity. Surface functionalities were verified using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The wear properties of the coatings were determined by weight loss under conditions of a random motion pin-on-plate apparatus with the coated polyethylene plaques immersed in DI water. Based on these tests, the grafted surfaces exhibited an improved resistance to wear, compared to UHMWPE. Cell viability studies were used to confirm that the plasma treatment had no negative effects on the surface bio-toxicity. Based on the results, it is anticipated that the incorporation of these biocompatible polymer-grafted UHMWPE surfaces in metal-on-plastic orthopedic implants should improve their performance and longevity.