Additively manufactured self-defending bone implants to prevent implant-associated infection

Additively manufactured self-defending bone implants to prevent implant-associated infection

van Hengel, I.A.J.

Apachitei, I. (mentor)
Zadpoor, A.A. (mentor)
Zaat, S.A.J. (mentor)

Mechanical, Maritime and Materials Engineering

Biomechanical Engineering

Biomaterials & Tissue Biomechanics

2016-08-29

Background Due to an aging population, the incidence of total joint replacements has been increasing and is expected to double in the coming decade. Along with implantation, the incidence of implant-associated infection (IAI) has risen and forms a tremendous burden for health care. Therefore, effective preventive measures for IAI are desperately needed. The recent developments of additive manufacturing (AM) processes possess great potential to provide personalized orthopedic implants for future patients. Furthermore, AM generates new strategies to prevent IAI through the synthesis of antibacterial surfaces on AM implants that limit bacterial adhesion and/or promote bacterial killing. This study aimed to investigate the biomaterial characteristics and antibacterial activity of AM porous Ti6Al4V bonemini-implants. Methods Porous mini-implants designed in Solidworks and Matlab were synthesized with the AM process of selective laser melting (SLM). Thereafter the titanium oxide (TiO2) surface layer of these SLM mini-implants was modified by a plasma electrolytic oxdiation (PEO) process with a calcium and phosphate based electrolyte bearing silver nanoparticles (NPs). PEOprocessing resulted in PEO treated and silver-based (SLM PEO+Ag) mini-implants. SLM mini-implants were compared with solid miniimplants. Surface morphology of the mini-implants was analyzed by scanning electron microscopy (SEM), chemical composition by energy dispersive X-ray spectroscopy (EDS) and phase composition by X-ray diffraction (XRD). Silver ion release characteristics of SLM PEO+Ag mini-implants were studied for 1 month in a biomimetic environment. The antibacterial properties of the SLMPEO+Ag mini-implantswere evaluated by in vitro and ex vivo tests with Methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, the suitability of mini-implants for in vivo testing was investigated through the implantation in a murine cadaver. Results The design resulted in mini-implants with interconnected porosity and increased surface area compared to solid mini-implants. The presence of silver NPs onto SLM PEO+Ag mini-implants was confirmed by SEM and EDS. In addition, the formation of hydroxyapatite was demonstrated by XRD analysis. Silver ion release from SLM PEO+Ag mini-implants persisted up to 1 month and was enhanced for SLM PEO+Ag compared to solid PEO+Ag mini-implants. Furthermore, antibacterial testing indicated that leaching activity by SLM PEO+Ag mini-implants resulted in a larger zone of MRSA growth inhibition compared to solid PEO+Ag mini-implants. Furthermore, SLMPEO+Ag mini-implants had a bactericidal effect on MRSA in in vitro and ex vivo experiments. Moreover, MRSA biofilm formation was prevented by SLM PEO+Ag mini-implants. Cadaver implantation demonstrated the suitability of the mini-implants for use in an in vivo murine bone infection model. Conclusion Porous, SLM PEO+Ag mini-implants demonstrated enhanced antibacterial properties compared to solid PEO+Ag mini-implants. Therefore, SLM PEO+Ag mini-implants possess great potential for further development towards clinically applicable antibacterial bone implants that prevent IAI.

http://resolver.tudelft.nl/uuid:f02a00bd-e7b3-4ad8-aa03-94618e60bcc1

2020-08-29

Student theses

master thesis

(c) 2016 van Hengel, I.A.J.