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Session: Joints
Session starts: Friday 25 January, 13:00
Presentation starts: 13:15
Room: Lecture room 535

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Ingmar van Hengel (TU Delft)
Niko Eka Putra ()
Melissa Tierolf ()
Francisca Gelderman ()
Vito Valerio ()
Stefanos Athanasiadis ()
Raisa Grotenhuis ()
Ad Fluit ()
Bram van der Eerden ()
Lidy Fratila-Apachitei ()
Iulian Apachitei ()
Amir Zadpoor ()

Abstract:
Everyone knows someone who received a hip or knee implant. Together with the number of patients requiring such an implant, the number of complications is on the rise: implant-associated infections and aseptic loosening have great impact on quality of life and functioning in society. We aim to prevent these complications through the generation of self-defending, multifunctional bone implants that simultaneously prevent infection and enhance fixation of the implant by stimulation of bone stem cells. For this purpose we designed highly porous titanium implants that were additively manufactured by selective laser melting (SLM) resulting in implants with a 4 times enhanced surface area compared to solid implants. Subsequently, the implant’s surface was biofunctionalized using an electrochemical surface modification method, namely plasma electrolytic oxidation (PEO). Through addition of calcium and phosphate species as well as silver nanoparticles (AgNPs) to the PEO electrolyte these elements were incorporated in the growing TiO2 layer during the PEO process. It is important to note that the AgNPs become fully immobilized in the surface, thereby preventing the NPs from free circulation and potential nanotoxic effects. Following PEO processing, the surface morphology, phase and chemical composition as well as ion release kinetics were studied. The antibacterial capacity was evaluated against methicillin-resistant Staphylococcus aureus (MRSA), a highly resistant bacteria that is frequently involved in implant-associated infections. Meanwhile, osteogenesis was studied using human mesenchymal stem cells (MSC). The PEO treatment of the highly porous implants resulted in a bioactive surface with interconnected micropores in which hydroxyapatite phases were demonstrated. Release of silver ions from the implant surface was demonstrated for at least 28 days, indicating a long-lasting infection prevention capacity. Furthermore, the surface proved to stimulate the differentiation of mesenchymal stem cells (MSC) towards osteoblasts, thereby stimulating osseointegration and proper fixation between bone tissue and implant. At the same time, the porous implants demonstrated enhanced in vitro and ex vivo antibacterial activity against MRSA compared to solid implants. Currently, we are testing other antimicrobial and osteogenic elements to further improve these capacities and generate a self-defending implant applicable for the clinic.