title: Improving tribological and anti-bacterial properties of titanium external fixation pins through surface ceramic conversion.
abstract: In this study, an advanced ceramic conversion surface engineering technology has been applied for the first time to self-drilling Ti6Al4V external fixation pins to improve their performance in terms of biomechanical, bio-tribological and antibacterial properties. Systematic characterisation of the ceramic conversion treated Ti pins was carried out using Scanning electron microscope, X-ray diffraction, Glow-discharge optical emission spectroscopy, nano- and micro-indentation and scratching; the biomechanical and bio-tribological properties of the surface engineered Ti pins were evaluated by insertion into high density bone simulation material; and the antibacterial behaviour was assessed with Staphylococcus aureus NCTC 6571. The experimental results have demonstrated that the surfaces of Ti6Al4V external fixation pins were successfully converted into a TiO2rutile layer (~2 μm in thickness) supported by an oxygen hardened case (~15 μm in thickness) with very good bonding due to the in-situ conversion nature. The maximum insertion force and temperature were reduced from 192N and 31.2 °C when using the untreated pins to 182N and 26.1 °C when the ceramic conversion treated pins were tested. This is mainly due to the significantly increased hardness (more than three times) and the effectively enhanced wear resistance of the cutting edge of the self-drilling Ti pins following the ceramic conversion treatment. The antibacterial tests also revealed that there was a significantly reduced number of bacteria isolated from the ceramic conversion treated pins compared to the untreated pins of around 50 % after 20 h incubation, P < 0.01 (0.0024). The results reported are encouraging and could pave the way towards high-performance anti-bacterial titanium external fixation pins with reduced pin-track infection and pin loosing.
authors.affiliation: Royal Derby Hospital, Derby, DE22 3NE, UK. dongh100@gmail.com.
authors.forename: Huan
authors.initials: H
authors.lastname: Dong
authors.affiliation: School of Metallurgy and Materials, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Mukinay
authors.affiliation: School of Engineering, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Maojun
authors.initials: M
authors.lastname: Li
authors.affiliation: School of Engineering, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Hood
authors.affiliation: School of Engineering, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Sein Leung
authors.initials: SL
authors.lastname: Soo
authors.affiliation: Royal Derby Hospital, Derby, DE22 3NE, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Cockshott
authors.affiliation: School of Dentistry, University of Birmingham, Birmingham, B4 6NN, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Sammons
authors.affiliation: School of Metallurgy and Materials, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Li
mesh_terms: D000497:Alloys; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D001696:Biomechanical Phenomena; D001858:Bone Nails; D002516:Ceramics / Q000737:chemistry*; D020099:Coated Materials, Biocompatible; D016267:External Fixators; D008422:Materials Testing; D008826:Microbial Sensitivity Tests; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D013203:Staphylococcal Infections / Q000188:drug therapy*; D013211:Staphylococcus aureus / Q000187:drug effects; D013696:Temperature; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D000497:Alloys; D000900:Anti-Bacterial Agents; D020099:Coated Materials, Biocompatible; C031462:titanium alloy (TiAl6V4); C009495:titanium dioxide; D014025:Titanium