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Effect of synovial fluid composition and surface topography modification on lubrication of joint replacements
Hekrle, Pavel ; Vampola, Tomáš (referee) ; Vrbka, Martin (advisor)
The main objective of this diploma thesis is to determine the influence of synovial fluid compodition and the influence of surface microtextures on lubrication of hip join replacements. For all experiments, hip joint simulator based on the pendulum principle was utilized. Metal heads (CoCrMo) manufactured by B Braun company and and tailor made acetabular cups from optical glass were used as contact couples. Acetabulum dimensions were fabricated according to dimensions of real implants. Experiments with surface microtextures simulated walking cycle for 210 s and development of lubrication film over time was observed.Results have shown that all types of tested structures improved lubrication of contact area, where the best results were obtained for square and triangle shapes respectively. Second set of experiments was based on the fact, that the composition of synovial fluid of healthy people differs from the composition of patients with various stages of osteoarthritis. Therefore, experiments with different model fluids were compared, which in their composition correspond to different groups of patients. For the model fluid that corresponds to the largest number of cases, experiments with individual components and combinations thereof were subsequently performed to provide a more detailed description of how these components affect the film-forming mechanism. The results show, that a change in fluid composition of patients with osteoarthritis can have a major negative effect on fluid formation process within the pair.
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An investigation of lubrication of knee joint replacement
Sýkora, Tomáš ; Horák, Zdeněk (referee) ; Nečas, David (advisor)
This diploma thesis deals with an experimental analysis of knee joint replacement lubrication. The experiments were realized at a knee joint simulator which can apply conditions according to certain standard and survey the phenomena by using fluorescence microscopy. The aim of thesis is to clarify the influence of particular components of synovial fluid on the lubrication process. The intensity of fluorescence expresses dimensionless parameter of a lubrication film thickness. There was a fundamental study with mineral oils before the experiments with the synovial fluid. The study allows to have a look at contact transformation during walk. Results are shown in graphs as dependency of intensity on time, including pictures showing phenomena in the contact zone. Experiment results show that protein -globulin creates a layer on the surface. There is albumin on the layer and it makes the lubricating film thicker. The protein interaction is supported by hyaluronic acid and fosfolipids which stabilizes the created structure. According to lubrication is behaviour of film related to a complex structure of synovial fluid. Thesis gives more information about behaviour of synovial fluid and can be used for future development of knee replacements.
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Friction and lubrication of articular cartilage
Hilšer, Pavel ; Daniel, Matej (referee) ; Vrbka, Martin (advisor)
The main goal of this diploma thesis is to determine the role of hyaluron acid and phospholipids on friction and lubrication of articular cartilage in regard to optimization of viscosupplements. This is carried out by measuring the coefficient of friction of the articular cartilage with several lubricants. Cartilage is lubricated particularly by a conventional viscosuplement, optimized viscosuplementation with phospholipids and model synovial fluid. In order to observe the function of those viscosuplements in the human body, both are mixed with the model synovial fluid, ubiquitous in human joints, in given ratio. Experiments revealed high friction when it comes to convectional viscosupplementation as opposed to low friction of the optimized viscosuplement with phospholipids. The same situation occurs when cartilage is lubricated with those viscosuplements mixed with model synovial fluid which might lead to development of a new, better, viscosupplementation based on hyaluron acid and phospholipids.
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Biotribology of articular cartilage
Furmann, Denis ; Látal, Roman (referee) ; Nečas, David (advisor)
This bachelor thesis deals with biotribology of articular cartilage. The first part deals with the analysis of individual building components of cartilage. Another part is devoted to the definition of the tribological properties of cartilage with regard to friction, wear and lubrication. The thesis also briefly analyses selected publications dealing with articular cartilage biotribology. Two hypotheses have been formulated and verified on the basis of the processed articles. Will the friction coefficient fall at a higher load? Will the friction coefficient increase at higher speed? It has been experimentally confirmed that the friction coefficient value increases with increasing speed and decreasing load.
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The effect of synovial fluid composition on friction of joint cartilage
Furmann, Denis ; Daniel, Matej (referee) ; Nečas, David (advisor)
This thesis deals with the study of the effect of the constituents of the model synovial fluid on the frictional properties of articular cartilage. The influence of constituents, concentration, speed and load is observed. Experiments were performed on a commercial tribometer at configuration pin-on-plate. Several types of lubricants containing synovial fluid constituents have been selected for the experiments. Lubricants were prepared at two concentrations, the concentration of healthy individuals and at a concentration typical of for osteoarthritic patients. Speeds 5 and 10 mm/s and 5 and 10 N loads were used for all experiments. It is shown that when using only lubricant containing proteins, no difference in the coefficient of friction is observed and the effect of concentration is also not observed. The addition of hyaluronic acid has a synergistic effect with -globulin, however in the case of lubricants containing albumin, the effect is opposite. After the addition of phospholipids, no significant effect on friction is observed in -globulin containing lubricants. No significant effect of the composition and concentration of the lubricants is observed with the load change.
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Lubrication of hip joint replacements
Rebenda, David ; Hartl, Martin (referee) ; Vrbka, Martin (advisor)
This thesis deals with the experimental study of lubrication of hip joint replacements. The influence of the synovial fluid composition and the head material to the lubricating film thickness were asssesed by using a pendulum hip joint simulator. Both of these effects were assesed under static and dynamic loading conditions. The experimental results showed that the movement of the head against the cup is unnecessary for the separation of the rubbing surfaces by a layer of adsorbed proteins. Composition of the synovial fluid then significantly influences the thickness of the lubricating film. Two opposite extremes have been observed during tests with two model synovial fluids. The first fluid formed a very strong lubricating film. The second sample almost prevent adsorption of proteins and consequently formed only very thin lubricating film. The influence of the material is noticeable when comparing the results obtained with a metal head and ceramic heads. Metal head formes under the same conditions thicker lubricating film. This evidence may be partly influenced by different diametrical clearances, which were in the case of ceramic heads higher.
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Lubrication of knee joint replacement
Sadecká, Kateřina ; Horák, Zdeněk (referee) ; Vrbka, Martin (advisor)
The work deals with the lubrication of total knee replacement using fluorescence microscopy method, which allows unique insight into the contact between femoral and tibial component. The aim was to determine the effect of composition of synovial fluid (i.e. albumin, -globulin, hyaluronic acid and phospholipids) on film thickness and protein behaviour in contact, and also to determine changes of contact area during rotation. Since this is the first experimental work dealing with a knee replacement lubrication primarily, only simple rotation and load cycles were applied by the knee simulator. The output of the experiments was fluorescence intensity, which corresponds to dimensionless film thickness, over time. Another important output are the images directly showing the fluorescently labelled proteins in the contact area. The results show, there are fundamental differences in lubrication in different positions of rotation, due to changes of position, shape and behaviour of the contact area. The composition of the lubricant is also essential, since the proteins themselves form a relatively strong lubricating film and their mixture leads to a substantial reduction of film thickness, due to significant formation of clusters. Complex fluid, although it does not form the strongest layer, is able to create a quite continuous film.
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The Effect of Synovial Fluid Constituents on Lubrication of Hip Joint Replacements
Nečas, David ; Daniel,, Matej (referee) ; Sawae, Yoshinori (referee) ; Hartl, Martin (advisor)
Dizertační práce se zabývá mechanismy mazání v náhradách kyčelního kloubu. Byla provedena systematická studie formování proteinového filmu při zahrnutí různých materiálů a provozních podmínek. Hlavní pozornost je přitom věnována roli jednotlivých proteinů obsažených v synoviální kapalině při současné přítomnosti dalších proteinů. Jelikož metody aplikované v předchozích studiích neumožňovaly separovat jednotlivé složky maziva, byla vyvinuta optická měřící metoda na principu fluorescenční mikroskopie. Z důvodu verifikace metody byly provedeny dvě nezávislé studie zaměřené na měření tloušťky mazacího filmu a dělení maziva na výstupu mazaného kontaktu. Z důvodu určitých limitací fluorescenční mikroskopie byla dále využita i metoda optické interferometrie, jejíž využití je ilustrováno ve studii zabývající se formováním mazacího filmu v náhradách kyčelního klubu při uvažování reálné konformity třecích povrchů. Závěrečná část práce představuje nový metodologický přístup založený na in situ pozorování kontaktní oblasti umožňující popsat roli jednotlivých proteinů ve vztahu k vývoji tloušťky mazacího filmu. Práce obsahuje originální výsledky, které přináší nové poznání v oblasti biotribologie náhrad kyčelního kloubu vedoucí k dalšímu vývoji implantátů při snaze zabránit jejich selhání v důsledku omezené životnosti.
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THE BIOCHEMICAL PROCESS OF LUBRICANT FILM FORMATION INSIDE HIP JOINT REPLACEMENT
Rufaqua, Risha ; Ruggiero,, Alessandro (referee) ; Muoz, Anna Neus Igual (referee) ; Vrbka, Martin (advisor)
The dissertation thesis deals with the lubricant film formation chemistry on hip implant material surfaces with synovial fluid components. Biochemical and tribological properties of synovial fluid after joint replacement are focused, precisely on the chemical composition of the formed lubricating film and chemical structural changes of the associated constituents under mechanical loading. Nevertheless, the synovial fluid components‘ chemical structural changes after the joint replacement are rarely addressed and require further attention. Including metal and ceramics, various combination implant materials were applied within the lubricants of synovial fluid constituents separately and different model synovial fluids to reveal the biochemical reactions and frictional coefficients for understanding the possible lubrication mechanism. Raman Spectroscopic technique is manifested as the most appropriate method to explain the biochemical behaviour of synovial fluid and chemisorption on the surface of the implant material. The method is depicted presenting two different studies focusing on the chemical structure of the synovial fluid film on the implant surface and frictional coefficient measurement of the contact pair within the artificial hip joint. This latest methodological precedent also facilitates to evaluate the chemical structural change of the synovial fluid due to the tribological activity in the hip prosthesis. The thesis expounds original results concerning biotribology to increase the depth of knowledge on joint replacement procedure and to enhance the longevity of the orthopaedic implantations.
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Study on flow and viscoelastic properties of laboratory prepared synovial fluids by macrorheological techniques
Veldamonová, Aneta ; Heger, Richard (referee) ; Smilek, Jiří (advisor)
This bachelor thesis deals with preparation and characterization of synthetic synovial fluid. Preparation was focused mostly on finding proper ratios of substances existing in real synovial fluid which have influence on viscoelastic properties. Based on study of literature, these substances are hyaluronic acid, lubricin, phospholipids and proteins. Samples of real synovial fluid from horse hock acquired from University of veterinary and pharmaceutical sciences Brno were tested for comparation with synthetically prepared synovial fluid. Both synthetic and real synovial fluid were characterized by macrorheological techniques. The experimentally obtained data were then compared with data from the patent on which the preparation of synthetic synovial fluid was based on. Thermogravimetry and isothermal thermogravimetry were used as additional method for the study of moisture and water binding of synovial fluids.
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