Colorimetric interferometry
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The aim of this study is to consider the relevance of in situ measurements of bovine serum film thickness in the optical test device that could be related to the function of the artificial hip joint. It is mainly focussed on the effect of the hydrophobicity or hydrophilicity of the transparent surface and the effect of its geometry. Film thickness measurements were performed using ball-on-disc and lens-on-disc configurations of optical test device as a function of time. Chromatic interferograms were recorded with a high-speed complementary metal-oxide semiconductor digital camera and evaluated with thin film colorimetric interferometry. It was clarified that a chromium layer covering the glass disc has a hydrophobic behaviour which supports the adsorption of proteins contained in the bovine serum solution, thereby a thicker lubricating film is formed. On the contrary, the protein film formation was not observed when the disc was covered with a silica layer having a hydrophilic behaviour. In this case, a very thin lubricating film was formed only due to the hydrodynamic effect. Metal and ceramic balls have no substantial effect on lubricant film formation although their contact surfaces have relatively different wettability. It was confirmed that conformity of contacting surfaces and kinematic conditions has fundamental effect on bovine serum film formation. In the ball-on-disc configuration, the lubricant film is formed predominantly due to protein aggregations, which pass through the contact zone and increase the film thickness. In the more conformal ball-on-lens configuration, the lubricant film is formed predominantly due to hydrodynamic effect, thereby the film thickness is kept constant during measurement.
- MeSH
- adsorpce MeSH
- biomechanika MeSH
- hydrofobní a hydrofilní interakce MeSH
- interferometrie metody MeSH
- kyčelní protézy * MeSH
- lubrikanty chemie MeSH
- sérum chemie MeSH
- skot MeSH
- smáčivost MeSH
- testování materiálů metody MeSH
- zvířata MeSH
- Check Tag
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
An advanced surface engineering process combining micro-texture with a plasma carburising process was produced on CoCrMo femoral head, and their tribological properties were evaluated by the cutting-edge pendulum hip joint simulator coupled with thin film colorimetric interferometry. FESEM and GDOES showed that precipitation-free C S-phase with a uniform case depth of 10μm was formed across the micro-textures after duplex treatment. Hip simulator tests showed that the friction coefficient was reduced by 20% for micro-metre sized texture, and the long-term tribological property of microtexture was enhanced by the C-supersaturated crystalline microstructure formed on the surface of duplex treated CoCrMo, thereby enhancing biotribological durability significantly. In-situ colorimetric interferometry confirmed that the maximum film thickness around texture area was 530nm, indicating that the additional lubricant during sliding motion might provide exceptional bearing life.
The present paper represents Part II of the extensive study focused on the lubrication of hip joint replacements. The main goal is to assess the fundamentals of lubrication considering both hard-on-soft (Part I) and hard-on-hard (Part II) bearing pairs. In addition, the effect of individual constituents contained in the model fluid is clarified. For this purpose, multiple model fluids of various composition were employed. In this part of the study, metal-on-glass contact representing hard bearing pairs was observed in situ using pendulum hip joint simulator in combination with thin film colorimetric interferometry method. The designed test consists of initial static loading/unloading phase for the determination of adsorption of molecules on rubbing surfaces. This period is followed by swinging of the pendulum and latest static part under constant load. Three groups of measurements were carried out while fourteen different lubricants were tested. Initially, the experiments were performed with albumin-based model fluid. In that case a substantial positive effect of hyaluronic acid was identified. In contrast, the fluids with γ-globulin as a base constituent showed improved lubrication conditions when phospholipids were added to the solution. Finally, considering the complex fluid, a combined effect of hyaluronic acid and phospholipids caused a better endurance of the lubricant film. The latest part of the paper aims on the comparison of film formation considering hard and soft pairs, highlighting some clear differences. In general, hard pairs exhibit clear decreasing tendency of the film during swinging motion while opposite behaviour was observed for soft pairs.
The objective of the present study is to clarify the lubrication processes within artificial joints considering the ceramic femoral heads focusing on the role of particular proteins. Two optical methods were employed; colorimetric interferometry and fluorescent microscopy. The experiments were conducted in ball-on-disc configuration, where the ball is made from ceramic (Sulox(TM), BIOLOX(®)delta) and the disc from optical glass. The measurements were realized under pure rolling, partial negative and partial positive sliding, to get a complex information about the protein film behaviour under various conditions. Moreover, two different speeds were investigated; 5.7 and 22 mm/s, respectively. The contact was lubricated by saline solutions containing albumin and γ-globulin in a ratio 2:1, while the total protein concentration was 10.5 mg/ml. Under pure rolling conditions, the film thickness gradually increases with time/rolling distance independently of material and rolling speed, while the dominant fluid constituent is albumin. In the case of negative sliding, the film formation is time/distance/speed dependent. At lower speed, both proteins contribute to film thickness; at higher speed, the effect of γ-globulin is not substantial. When the disc is faster, the character of film formation is similar to the metal component in the case of Sulox ceramic. Biolox ceramic shows a different behaviour, while for both materials, the contribution of γ-globulin increases with increasing speed. As most of the results can be well explained in terms of specific proteins, it can be concluded that the experimental approach is suitable for the investigation of protein film formation considering the ceramic materials.
- MeSH
- albuminy chemie MeSH
- gama-globuliny chemie MeSH
- keramika * MeSH
- kyčelní protézy * MeSH
- lidé MeSH
- lubrikace * MeSH
- náhrada kyčelního kloubu MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The aim of the present paper is to provide a novel experimental approach enabling to assess the thickness of lubricant film within hip prostheses in meaning of the contribution of particular proteins. Thin film colorimetric interferometry was combined with fluorescent microscopy finding that a combination of optical methods can help to better understand the interfacial lubrication processes in hip replacements. The contact of metal femoral head against a glass disc was investigated under various operating conditions. As a test lubricant, the saline solution containing the albumin and γ-globulin in a concentration 2:1 was employed. Two different mean speeds were applied, 5.7 and 22mm/s, respectively. The measurements were carried out under pure rolling, partial negative and partial positive sliding conditions showing that kinematic conditions substantially affects the formation of protein film. Under pure rolling conditions, an increasing tendency of lubricant film independently on rolling speed was detected, while the total thickness of lubricant film can be attributed mainly to albumin. When the ball was faster than the disc (negative sliding), a very thin lubricant film was observed for lower speed with no significant effect of particular proteins. The increase in sliding speed led to the increase of film thickness mainly caused due to the presence of γ-globulin. On the contrary, when the disc was faster than the ball (positive sliding), the film formation was very complex and time dependent while both of the studied proteins have shown any qualitative change during the test, however the effect of albumin seems to be much more important. Since a very good agreement of the results was obtained, it can be concluded that the approach consisting of two optical methods can provide the fundamental information about the lubricant film formation in meaning of particular proteins while the simultaneous presence of other constituents in model synovial fluid.
Závěrečná zpráva o řešení grantu Interní grantové agentury MZ ČR
1 svazek : ilustrace ; 30 cm
Největším problémem totální endoprotézy (TEP) kyčle je aseptické uvolnění a periprotetická osteolýza, které jsou podmíněny typem a rychlostí otěru kloubních povrchů. Opotřebení není primární funkcí artikulačních materiálů, nýbrž důsledkem interakcí řady faktorů a podmínek. Tyto faktory a podmínky je možné dílem simulovat in vitro a studovat pomocí optické kolorimetrické interferometrie. Složení kloubní kapaliny, tlakové, rychlostní a další parametry experimentu budou vycházet z reálné situace. Proto je součástí navrhovaného projektu také analýza reálné kloubní kapaliny získané v průběhu reoperace/implantace TEP kyčle. Výstupy projektu budou využitelné při výrobě kloubních implantátů (materiálové a konstrukční inženýrství), při vysvětlení rozdílů v rychlosti opotřebení, přežití implantátu, resp. při pochopení biologických reakcí kolem TEP.; The main problem concerning total hip arthroplasty (THA) is aseptic loosening and periprosthetic osteolysis, both are related to the type and rate of joint surface wear. Wear is not a primary function of joint materials but is a result of the interaction of various factors and conditions. These factors and conditions can be simulated at least partially in vitro and analyzed using optic colorimetric interferometry. The composition of joint fluid, pressure, speed and other parameters of the experiment will evolve from the real situation. Therefore analysis of real joint effusions acquired during reoperation/ implantation of THA is part of the proposed study. Results of the project will be exploitable in the construction of joint implants (material and constructive engineering), in clarifying differences in wear rates, survival of implants, and also in understanding the biologic reactions around THA. Therefore, the proposed project is fully in accordance with the R&D program MH Czech Republic.
- MeSH
- biokompatibilní materiály MeSH
- kolorimetrie MeSH
- kyčelní protézy MeSH
- lubrikace MeSH
- náhrada kyčelního kloubu MeSH
- povrchové vlastnosti MeSH
- reoperace MeSH
- rozhraní kost/implantát MeSH
- synoviální tekutina MeSH
- Konspekt
- Ortopedie. Chirurgie. Oftalmologie
- NLK Obory
- ortopedie
- NLK Publikační typ
- závěrečné zprávy o řešení grantu IGA MZ ČR
