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Influence of viscosupplementation on cartilage lubrication
Ondra, Martin ; Horák, Zdeněk (referee) ; Ranuša, Matúš (advisor)
This work deal with the determination of the effect of viscosupplementation on the lubrication of articular cartilage in the beginning phase of osteoarthritis. This effect was evaluated based on the development of CoF measured by a tribometer in configuration pin-on-plate. The tribological model of incipient osteoarthritis was simulated by using two articular cartilages lubricated with osteoarthritic synovial fluid to which viscosupplementation agents were added. These preparations differed mainly in cross-linking and molecular weight of hyaluronic acid (HA). Measurements have shown that viscosupplementation may be effective in the beginning phase of osteoarthritis. The efficacy of viscosupplementation preparations with cross-linking HA was significantly higher compared to the efficacy of viscosupplementation preparations without cross-linking. These results support the use of viscosupplementation to delay the advanced stage of osteoarthritis.
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The Effect of Synovial Fluid Constituents on Friction and Lubrication of Articular Cartilage
Čípek, Pavel ; Dr. Prashant K. Sharma (referee) ; Muňoz, Anna Neus Igual (referee) ; Vrbka, Martin (advisor)
Práce se zabývá problematikou biotribologie modelu synoviálního kloubu. Cílem práce je popsat vliv složek synoviální kapaliny na formování mazacího filmu v modelu synoviálního kloubu. Práce je zaměřena na experimentální analýzu součinitele smykového tření a jeho propojení s pozorováním adsorbovaného mazacího filmu v kontaktu pomocí fluorescenční mikroskopie. Součástí práce je návrh tribometru, který umožňuje vizualizaci v průběhu experimentů. Tribometr je vyroben, kalibrován a verifikován pomocí komerčního tribometru. Dále je součástí práce návrh metodiky experimentů včetně návrhu postupu pro zpracování a hodnocení výsledků. Pro zpracování záznamu z vizualizace kontaktu byl navržen speciální software, který pracuje na principu segmentace obrazu. Poslední část práce je zaměřena na aplikaci vyvinuté metodologie spolu s nově navrženým tribometrem, což umožňuje posoudit roli složek modelové kapaliny u formování mazacího filmu v modelu synoviálního kloubu. Experimentální část je založena na měření tření za současné vizualizace kontaktu. Tato práce prezentuje originální výsledky rozšiřující oblast biotribologie synoviálního kloubu, které mohou pomoci dalšímu rozvoji účinné léčby pacientů s nemocnými klouby.
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Biotribology of artificial tears for the treatment of dry eye syndrome
Černohlávek, Mikuláš ; Daniel, Matej (referee) ; Vrbka, Martin (advisor)
This master thesis is a part of the project TAČR TREND, which aim is the development of new ingredient for treatment of dry eye syndrome. Developed ingredient is derivative of hyaluronic acid, which is in this thesis compared with native hyaluronic acids and commercial eye drops. Aim of this thesis is to describe rheological and tribological properties of measured samples in terms of viscosity, mucoadhesivity and coefficient of friction. Coefficient of friction was measured on created tribological model of the eye in pin-on-plate configuration which represents physiologically relevant sliding speeds of blinking. Comparison with native hyaluronic acids and commercial products of eye drops showed, that derivative reaches higher values of viscosity, has mucoahesive properties and has low values of coefficient of friction. Those key parameters show that modification of hyaluronic acid is promising way for drug development for dry eye disease.
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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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Design of Simulator for Friction Analysis in a Knee Joint
Dobrovolná, Lucie ; Studený, Zbyněk (referee) ; Sedlák, Josef (advisor)
This bachelor thesis deals with the construction of a device simulating the kinematics of the knee joint. Boundary conditions are inspired by the ISO 14243-3 standard and are based on the selection of suitable components. The simulator will be able to record the course of the coefficient of friction between the cartilage forming the translational motion, the CoCr head forming the rotational motion and the pressing force, thus helping to better understand the biotribological processes between the selected surfaces. The design must be developed with respect to the relative movement of components, sample material and lubrication. The introductory part of the text deals with an overview of current knowledge, which serves as the main input to the creation of the structure. Based on the research part, several conceptual solutions are created in the field of construction and method of friction measurement. The resulting solution is selected from the proposed concepts, which meets predetermined conditions and contains specific drives and sensors.
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Design of a bath on the device for testing human joints
Svoboda, Tomáš ; Vrbka, Martin (referee) ; Čípek, Pavel (advisor)
The bachelor thesis deals with the design of the bathtub of an experimental device for testing human joints. Tribometer is used for experimental measurement of friction and visualization of real cartilage film in flooded synovial fluid. The result of this work is the design of air releasing, heating and sealing the bathtub in which the synovial fluid is located. By removing air bubbles and heating the liquid to the temperature of the human body, more accurate shear coefficient values and improved contact visualization are achieved. This should lead to a better understanding of the friction and lubrication processes in the synovial joint. The result of this work is chosen optimal design variant and production drawing documentation.
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The effect of surface condition of artificial joint cup on the friction coefficient
Černohlávek, Mikuláš ; Dočkal, Kryštof (referee) ; Nečas, David (advisor)
This bachelor’s thesis deals with the effect of microtextured surface of an artificial joint cup on a friction coefficient. The primary aim of this thesis was to compare friction coefficients of original and microtextured joint cups. Experimental measurements were made on pendulum hip joint simulator and results were evaluated in Matlab. Four types of femoral heads (CoCrMo, BIOLOX Delta, BIOLOX Forte and oxinium) and three types of lubricants (PBS, model synovial fluid and hyaluronic acid solution) were used during the measurements. The results show, that using PBS and synovial fluid leads to decrease of the coefficient of friction while using modified joint cup. We can assume that microtextured surface of artificial joint cup (separately or in combination with microtextured femoral head) could be a significant benefit for prolonging lifespan of implants.
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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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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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Design of parts of tribometer with reciprocating motion
Dražka, Ondřej ; Vrbka, Martin (referee) ; Čípek, Pavel (advisor)
The bachelor thesis deals with design of parts of tribometer with reciprocating motion. Several conceptual solutions are made on base of existing studies from which the best solution for given application is selected. The tribometer will be used for experimental measuring on real cartilage which should lead to better understanding of friction and lubrication processes in synovial joint. The outcome of this thesis are component parts along with the manufacturing drawings.
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