Is surface chemical composition important for orthopaedic implant materials?

Ti-6Al-7Nb (NS) in its 'standard' implant form has been previously shown to be detrimental to fibroblast growth and colonisation on its surface. Specific aspects of the NS topography have been implicated, however, the contribution of its unique surface chemistry to the cell behaviour was unknown. By evaporating either gold or titanium on the surface of standard NS, two different model surface chemistries could be studied with the same characteristic standard NS topography. Two other 'standard' orthopaedic topographies, that of stainless steel (SS) and of 'commercially pure' titanium (TS) were also treated in a similar manner. All materials elicited behaviour similar to their uncoated counterparts. For coated SS and TS, cell proliferation was observed, cells were well spread and displayed mature focal adhesion sites, and associated cytoskeletal components. For coated NS, cell proliferation was compromised, cells remained rounded, filopodia attached and seemed to probe the surface, especially the beta -phase particles, and both the focal adhesion sites and the microtubule network were disrupted by the presence of these particles. These results confirmed, that in the instance of NS, the topography was the primary cause for the observed stunted cell growth. For biomaterials studies, the standardisation of surface chemistry used here is a valuable tool in allowing vastly different materials and surface finishes to be compared solely on the basis of their topography.