Investigation of the effects of engineered surface texture on the formation of biofilms leading to periprosthetic joint infection

Student thesis: Doctoral Thesis


With an ever-increasing populous requiring a total arthroplasty procedure and in particular Total Hip Arthroplasties (THA), the associated complications will become ever more apparent [8]. Although heralded as being amongst the most successful surgeries performed within orthopaedics, significant complications such as Periprosthetic Joint Infection (PJI) still occur within 2% of surgeries [10]. The treatment of PJI faces challenges due to the predisposition of the bacteria to form biofilms upon the biomaterial surface. Eradication of biofilms is difficult and is hampered by them becoming recalcitrant to antibiotic approaches and often the only course of treatment is a revision procedure. However, with a revision procedure the incidence of PJI increases. Exhaustive efforts across research are being spent on novel and innovative ways to eradicate biofilm formation upon an engineered biomaterial surface. Engineered surface within the context of this thesis refers to one that has been designed for purpose of being a biomaterial, that is one that incorporates intentional characteristics, topographies and or properties. A common thread between published literature is that the surface itself can influence the tendency of bacteria to colonise the surface and surface roughness is a crucial indicator of the magnitude of the biofilm formation. The work conducted within this thesis was devised in such a way as to investigate this microbial/ biomaterial interface through the application of advanced metrology techniques and microbiological processes in combination with surface modification methodologies. Areal surface characterisation was applied, contrary to the much more commonly reported, profile measurements and thus allows for a deeper understanding and true indication of the surface.A series of Ti6Al4V surfaces were developed containing prosthesis relevant surfaces/ coatings and modified surfaces to investigate their influence over biofilm formation. A thorough surface characterisation was conducted alongside the growth of Staphylococcus aureus biofilms upon the surface. The findings concluded that the influence of the surface is profound on the magnitude of growth, with surface parameters describing texture contributions and feature spacing showing the highest statistical correlation with growth, with linear trends present throughout the studies. Surfaces that were engineered to promote osseointegration for the overall success of the implant, exhibiting a highly stochastic, porous surface exhibited orders of magnitude increases in biofilm formation in comparison to alternate prosthesis relevant finishes such as a grit blasting. Studies were aimed at highlighting key features and characteristics that influence the growth. Within literature a commonly reported observation is that the increase in surface area inherent with an increase in surface roughness harbours increased bacterial colonisation, the findings from studies contained within have found that this may be a generalised observation and parameters defining where this increase occurs within the topography may better describe this relationship. Finally, the influence of measurement configuration was investigated for datasets acquired through computed tomography. It was found that these configurable set-up parameters dictate the quality of the datasets obtained, with significant impact on parameters and characteristics extracted from the surface.
Date of Award21 Feb 2024
Original languageEnglish
SponsorsEngineering and Physical Sciences Research Council
SupervisorPaul Bills (Main Supervisor), Paul Humphreys (Co-Supervisor) & Leigh Fleming (Co-Supervisor)

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