| 研究課題/領域番号 |
14F04783
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| 研究機関 | 京都工芸繊維大学 |
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研究代表者 |
PEZZOTTI G. 京都工芸繊維大学, 材料化学系, 教授 (70262962)
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| 研究分担者 |
MARIN ELIA 京都工芸繊維大学, 材料化学系, 外国人特別研究員
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| 研究期間 (年度) |
2014-04-25 – 2017-03-31
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| キーワード | BIOCERAMICS / BIOINERTNESS / HIP JOINT / WEAR / RAMAN SPECTRA |
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| 研究実績の概要 |
In the latest activity of JSPS Long Term Fellowship program, research has been mainly focused on characterizing wear and tribological testing of in vitro simulated and retrieved ceramic and polymeric prosthetic components of hip implants. The results clearly showed that standard laboratory simulations usually underestimate the amount of damage sustained by the prosthetic implant in-vivo and, in particular, the amount of tetragonal to monoclinic transformation in zirconia toughened alumina (ZTA), which results in a decrease of mechanical properties. From a comparison between analyses performed on retrieved implants and simulated laboratory tests, it was possible to obtain new, more predictive equations to estimate the amount of damage suffered by a prosthetic implant, taking also into account catalytic effects such as the presence of metal staining.
The necessity to accurately analyze the surface of femoral heads in which the operating conditions (angle, contact locations, contact loads) were unknown led to the development of a highly resolved, Raman testing method that could be applied to the whole surface of the implant obtaining data about surface roughness, stresses and crystallography. This could be obtained with an operator that manually rotated the femoral heads up to a certain degree on two axes and performs a standardized measurement. The analyses were then supported by the development of an automated software capable to analyze hundreds of spectra per minute, to remove artifacts and signal bias and to reconstruct three dimensional maps at the component surface.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
The results of this JSPS Long Term Fellowship research are in line with the original research plan submitted at the beginning of 2014. A preliminary, detailed characterization program showed that an innovative ceramic material, silicon nitride, could become an effective alternative to consolidated prosthetic implant materials such as zirconia toughened alumina, especially in ceramic vs polyethylene couplings. Apart from tribological applications, the surface chemistry of silicon nitride was effectively tailored in order to promote osteo-induction, osteo-conduction and osteo-integration, obtaining results comparable if not superior to consolidate industrial standards such as Al2O3 and anodized titanium.
The simulated, tribological testing performed with different lubrication conditions on standard industrial zirconia toughened alumina samples led to a better comprehension of the link between wear, cathodoluminescence emission and oxygen vacancies in oxide biomaterials and in particular showed that dry lubrication can potentially lead to a faster and stronger degradation compared to lubricated conditions.
The study of surgical retrivals was used to check and compare the simulated results with the condition of the surfaces after different amounts of time in-vivo.
The research fellow consolidated his knowledge of computer programming, finite elements analysis, 3d-CAD and learned new analytical techniques. These knowledge was combined and used to obtained automated and reliable automated protocols that will allow faster and more reliable analyses of orthopaedic biomaterials.
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| 今後の研究の推進方策 |
In the last period of the JSPS Long Term Fellowship research, an innovative support for the automated analysis of arthroprosthetic implants will be developed and assembled, following the schematics designed by the research fellow thanks to the experience gained during this project. This new system will allow to rotate femoral heads or acetabular cups of diameter comprised between 28 and 40 mm on two axes in order to perform analysis of large portions of curve surfaces without the need for support and manipulation from a human operator. The possibility to automate the analytical process will decrease the time required to perform a complete scan of the surface and increase the precision of the measurements, thus reducing the risk associated with human errors during data acquisition. The support will also be interconnected with a dedicated software specifically coded by the research fellow in order to automatically extrapolate information about chemical composition, residual stresses and phase modifications of the materials, thus further reducing the need for manual operation and enabling the treatment of huge amounts of data in a relatively short amount of time. The fellow will also participate to an international conference in the field of biomaterials for orthopedic surgery and arthroplasty in order to present the results obtained during the project.
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