Anodized layers on titanium and titanium alloy orthopedic materials for antimicrobial activity applications

The development of a post operative infection following the implantation of a foreign material, such as a total joint prosthesis, is one of the most feared complications in orthopedic surgery. Prevention of such bacterial infections is best accomplished through the delivery of antibiotics as close to the implant as possible. A novel method has been developed to attach, retain and release antibiotics from titanium based materials. This technique consists of forming porous surface coatings by anodizing and using the surface chemical properties of the oxide coatings to attach antibiotics. Coatings with pores in the size range 0.1 to 10 μm have been formed in acid as well as basic solutions. The thickness, stoichiometry and morphology of the coatings have been characterized by Rutherford backscattering spectrometry and electron spectroscopy techniques. The isoelectric point of the coatings has been measured by a streaming potential technique. The attachment and retainment of gentamicin sulfate, a cationic antibiotic, to the coatings has been investigated using microbiological and streaming potential methods. In vitro test results have shown that the duration of antimicrobial activity on the surface of anodized materials is dependent on the porosity and isoelectric point of the coatings. Using microporous oxide coatings, it has been found that antimicrobial activity could be retained for almost two weeks.