Patent ID: 8888983

Claim:
A method of treating a metal implant, the implant having a first part of its surface provided with a rough metal finish having a surface roughness factor of at least 5 and having a second part of its surface provided with a polished surface having a surface roughness factor of less than 2, so as to incorporate a biocidal material in leachable form in the surface, the method comprising: (a) subjecting at least the first part of the surface to an anodising step with an anodising electrolyte, by applying an anodising voltage at a first voltage having a maximum value between 25 and 30 V so as to achieve passivation, and then ceasing the anodising process at the first voltage; (b) enclosing the first part of the surface with a watertight cover; (c) then contacting the metal object with an anodising electrolyte, and performing an anodising step by applying an anodising voltage at a second voltage having a maximum value between 30 V and 150 V to the metal object for sufficient time to passivate the second part of the surface by forming an anodised integral surface layer on the metal object; (d) continuing the application of the anodising voltage at the second voltage to produce pits through the integral surface layer formed in step (c); (e) then producing a hydrous metal oxide or phosphate in the surface layer by electrochemical or chemical reduction in contact with an electrolyte or a solution; and (f) then removing or separating the anodised metal object resulting from step (e) from the electrolyte or the solution of step (e); (g) then removing the watertight cover; wherein step (a) is carried out either before applying the watertight cover (step (b)) or after removing the watertight cover (step (g)); and (h) then contacting the anodised metal object with a biocidal material solution containing a biocidal material so as to incorporate said biocidal material into the passivated surface of the first part of the surface and the integral surface layer of the second part of the surface by ion exchange.