ABSTRACT Metallosis is a term used to describe staining of tissues exposed to metal particles and ions in- vivo. There is no explicit diagnosis for metallosis, but it is recognized as a significant health threat per the FDA as the released metals are associated with cardiotoxicity, neurotoxicity, and cancers. The overarching hypothesis of this work is that in-vivo non-pathogenic bacterial biofilms on spinal hardware affect the release of metal via corrosion thus causing metallosis in patients. To test this hypothesis, we will pursue the following aims: Specific Aim 1 will examine the association of bacteria with observed corrosion on the surfaces of spine hardware via the quantification of surface damage and the presence of bacterial associated biomolecules integrated into the damaged surfaces. To do so we will use surface optical microscopy to quantify the type and area coverage of surface modification whether wear or corrosion, over the entire device component, pedicel screw or rod. Optical microscopy determination of corrosion regions without existing mechanical damage will elucidate the total possible amount of metal release based on surface area measurements. How these surfaces are modified beyond mechanical damage will be characterized using Time of Flight-Scanning Ion Mass Spectroscopy (TOF-SIMS) and X-ray Photoelectron Spectroscopy (XPS). Work in Specific Aim 2 will characterize the bacterial milieu constituting the biofilms on explanted spine hardware in metallosis cases. Because of the lack of understanding of the in-vivo spinal instrumentation microbiome, this Aim will identify the common microbes associated with implant corrosion. The impact of this work will be to give insight to the mechanisms of in-vivo metal corrosion, thus leading to possible changes in clinical treatments, the necessity of new or modified materials, or changes to surgical procedures to reduce the risk of metallosis.