Biofilm Formation and Removal on Osseointegrated Implant Materials
The skin/percutaneous interface of osseointegrated (OI) implants is susceptible to infection, which can be devastating to patients causing excess pain, increased morbidity, and may require implant removal. Novel distal femoral OI implants with binary nitride coatings have been developed in Europe with little physiological modeling to collect microbiological evidence of resistance to bacterial attachment. This in vitro study evaluated a Ti-6Al-4V alloy coated with TiNbN and treated with low plasticity burnishing (LPB) to assess attachment and biofilm formation of methicillin-resistant Staphylococcus aureus (MRSA) under conditions that modeled a physiological environment. Washability of the material was also assessed and compared to standard Ti-6Al-4V alloy materials with a polished (“Color Buff”) or non-polished finish (“Satin Finish”). It was hypothesized that TiNbN/LPB treatments would resist bacterial adhesion and biofilm formation to a greater degree than the other two materials, and also have a higher degree of bacterial removal following a clinically-relevant wash regimen. Material types were exposed to a constant flow of Brain Heart Infusion Broth containing MRSA and were analyzed using bacterial quantification, surface coverage analysis, and SEM imaging. Quantification data showed no difference in bacterial attachment amongst the varying material types, and the wash regimen likewise did not result in significant differences. Surface coverage and SEM analysis confirmed results. The wash regimen led to a reduction of approximately 3 log10 reduction in bacteria for all material types. Though the results did not support the hypothesis that a TiNbN coating/LPB treatment might resist bacterial attachment/biofilm formation to a greater degree than other alloys, or have less bacteria after cleaning, results did support the potential importance of a daily wound-hygiene regimen at the skin/implant interface OI materials. This data set included all the bacterial quantification from this study.