Effects of surface roughness and texture on the bacterial adhesion on the bearing surface of bio-ceramic joint implants: An in vitro study

Reducing the bacterial adhesion to a bearing surface is crucial for increasing the success rate of joint replacement surgery and ensuring the service performance of joint replacement implants. In this study, the effects of the surface states (with a smoothness from the sub-micron to nano-scale level) on the adhesion of Staphylococcus aureus on yttria-stabilized zirconia bio-ceramic surfaces were considered. Ceramic surfaces with different surface states were prepared using various machining processes, and the surface characteristics, e.g., the surface roughness, surface topography, and wettability, were measured. It was found that achieving a nano-scale roughness on a bio-ceramic surface can significantly reduce the bacterial adhesion. The number of bacterial adhesion on a smooth surface with a roughness of Ra 1 nm is only 2% of that on a conventional surface with a roughness of Ra 205 nm; in addition, compared with a nano-scale surface with a unidirectional texture, achieving a uniform surface texture can further reduce the bacterial adhesion. As the surface roughness reduces from the sub-micron scale to the nano-scale level, the surface state gradually changes from hydrophobic to hydrophilic, and becomes unfavorable for the adhesion of hydrophobic S. aureus; in addition, the anchoring points for bacterial adhesion gradually decrease or even disappear, and hence the bacterial-surface bonding strength weakens. It was concluded that the preparation of a smooth nano-scale surface and the elimination of unidirectional surface textures can effectively inhibit the initial adhesion and proliferation of S. aureus on the bearing surfaces of a ceramic joint implant, which will reduce the occurrence of implant-related infections.