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Effect of Viscosupplementation on Friction of Articular Cartilage
Rebenda, David ; Sawae, Yoshinori (oponent) ; PhD, Axel C Moore, (oponent) ; Vrbka, Martin (vedoucí práce)
This dissertation thesis deals with the experimental analysis of hyaluronic acid-based viscosupplements which have been applied into the synovial joints in order to slow down the osteoarthritis progression. The main attention was paid to the effect of hyaluronic acid concentration and molecular weight on the articular cartilage friction as well as to the frictional changes after mixing of osteoarthritic synovial fluid with exogenous hyaluronic acid. An important part of the experiments was also an analysis of synovial fluid and hyaluronic acid rheological properties. The results showed that the hyaluronic acid molecular weight can significantly affect the viscosity and viscoelastic properties of the solution. However, no dependency between the hyaluronic acid rheological properties and friction in the articular cartilage contact was observed. The admixture of hyaluronic acid into the synovial fluid caused a significant decrease in the coefficient of friction within the contact but the differences between individual viscosupplements were not so significant. Nevertheless, the results indicate a possible change in the lubrication regime due to the high molecular weight of hyaluronic acid. These original results deepen the understanding of the mechanisms that occur in the synovial joint immediately after the injection of hyaluronic acid and can be further used in the future development of viscosupplements or in clinical practice.
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The Effect of Synovial Fluid Constituents on Lubrication of Hip Joint Replacements
Nečas, David ; Daniel,, Matej (oponent) ; Sawae, Yoshinori (oponent) ; Hartl, Martin (vedoucí práce)
The dissertation thesis deals with the lubrication mechanisms within hip joint replacements. A systematic study of protein film formation considering various materials and operating conditions was conducted, focusing on the role of particular synovial fluid proteins while the simultaneous presence of other proteins. Since the previously applied experimental approaches did not allow to separate the individual constituents of the model fluid, an optical measurement method based on fluorescent microscopy was developed. The verification of the method is presented performing two different studies focusing on the film thickness determination and lubricant rupture ratio at lubricated contact outlet, respectively. Due to several limitations of the fluorescent microscopy, the research was supported by the use of optical interferometry method, whose usage is demonstrated in the study dealing with the protein film formation in hip joint replacements considering real conformity of rubbing surfaces. The latest part of the thesis introduces a novel methodological approach enabling to assess the role of proteins in relation to protein film thickness based on in situ observation of the contact zone. The thesis presents original results extending the knowledge in hip replacement biotribology area towards the further development of implants preventing its failure due to limited service life.
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Effect of Viscosupplementation on Friction of Articular Cartilage
Rebenda, David ; Sawae, Yoshinori (oponent) ; PhD, Axel C Moore, (oponent) ; Vrbka, Martin (vedoucí práce)
This dissertation thesis deals with the experimental analysis of hyaluronic acid-based viscosupplements which have been applied into the synovial joints in order to slow down the osteoarthritis progression. The main attention was paid to the effect of hyaluronic acid concentration and molecular weight on the articular cartilage friction as well as to the frictional changes after mixing of osteoarthritic synovial fluid with exogenous hyaluronic acid. An important part of the experiments was also an analysis of synovial fluid and hyaluronic acid rheological properties. The results showed that the hyaluronic acid molecular weight can significantly affect the viscosity and viscoelastic properties of the solution. However, no dependency between the hyaluronic acid rheological properties and friction in the articular cartilage contact was observed. The admixture of hyaluronic acid into the synovial fluid caused a significant decrease in the coefficient of friction within the contact but the differences between individual viscosupplements were not so significant. Nevertheless, the results indicate a possible change in the lubrication regime due to the high molecular weight of hyaluronic acid. These original results deepen the understanding of the mechanisms that occur in the synovial joint immediately after the injection of hyaluronic acid and can be further used in the future development of viscosupplements or in clinical practice.
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The Effect of Synovial Fluid Constituents on Lubrication of Hip Joint Replacements
Nečas, David ; Daniel,, Matej (oponent) ; Sawae, Yoshinori (oponent) ; Hartl, Martin (vedoucí práce)
The dissertation thesis deals with the lubrication mechanisms within hip joint replacements. A systematic study of protein film formation considering various materials and operating conditions was conducted, focusing on the role of particular synovial fluid proteins while the simultaneous presence of other proteins. Since the previously applied experimental approaches did not allow to separate the individual constituents of the model fluid, an optical measurement method based on fluorescent microscopy was developed. The verification of the method is presented performing two different studies focusing on the film thickness determination and lubricant rupture ratio at lubricated contact outlet, respectively. Due to several limitations of the fluorescent microscopy, the research was supported by the use of optical interferometry method, whose usage is demonstrated in the study dealing with the protein film formation in hip joint replacements considering real conformity of rubbing surfaces. The latest part of the thesis introduces a novel methodological approach enabling to assess the role of proteins in relation to protein film thickness based on in situ observation of the contact zone. The thesis presents original results extending the knowledge in hip replacement biotribology area towards the further development of implants preventing its failure due to limited service life.
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