Biocorrosion and aseptic loosening of metal implants: novel pathophysiological mechanisms

Dieter Cadosch

    Research output: ThesisDoctoral Thesis

    355 Downloads (Pure)

    Abstract

    Metal orthopaedic devices exposed to a physiological environment remain prone to corrosion by several mechanisms, leading to the production of significant amounts of non-biocompatible wear particles and metal ions. Beside the well-known mechanical wear and electrochemical redox reactions, metal implants undergo corrosion through biological activities. The results presented in this thesis suggest that mature osteoclasts are able to enhance corrosion of titanium and stainless steel implants and contribute to the release of relevant amounts of corresponding metal ions into the peri-implant tissues and the systemic blood circulation. In addition to the increased osteolytic activity caused by wear particles, the results detailed in this thesis strongly suggests that released titanium ions in the 4+ oxidation state (Ti(IV)) contribute to the pathophysiological mechanism of aseptic loosening by stimulating both the bone metabolism and immune system through a series of direct and indirect pathways. Aseptic loosening is believed to be caused by an increased osteolytic activity at the bone-implant interface leading to loss of stability and ultimately implant failure. Titanium (IV) ions are able to directly induce the differentiation of osteoclast precursors toward mature and functional osteoclasts in ~20% of individuals. Additionally, Ti(IV) ions stimulate the secretion of pro-inflammatory cytokines that are known to enhance osteoclast recruitment, differentiation, activation and survival. More evidence is linking the immune system to the bone and to its involvement in the pathophysiology of aseptic loosening. Titanium (IV) ions influence phenotype and function of T-lymphocytes, resulting in activation of a CD69+ and CCR4+ Tlymphocyte and secretion of receptor activator of NF-κB ligand (RANK-L).
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2011

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