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Effect of femoral head size on friction and lubrication in THR
Bartošík, Jan ; Dzimko, Marián (referee) ; Vrbka, Martin (advisor)
This diploma thesis concerns itself with the experimental study of friction and lubrication in the artificial hip joint depending on the head size. Measurements were made in a hip joint simulator based on the principle of pendulum. For the friction measurements artificial joints, made from three material combinations and two diameters, from two companies were used. The measurements show that the material combination has a more significant effect to friction coefficient than the head size. Using a bigger head size shows a decrease in friction coefficient for all material combinations when compared to a smaller head size. For the measurement of lubrication film the colorimetric interferometry was applied. A metal-on-glass contact pair was used, where the glass cups were made according to the real measurements of the joint cups. Four types of hip replacements with diameters of 28 and 36 mm with two different diametral clearance were measured during a constant motion of 210 seconds. Measurements show, that the lubrication film in the hip joint with a small diametral clearance increases very fast over the 800 nm value. Contact surfaces in the hip joint with a large diametral clearance aren’t separated by the lubrication film, resulting in a damage of the chromium coating in cup. A thick lubrication film results in a higher friction coefficient, when compared with hip joints with a very thin or no lubrication film.
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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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Experimental analysis of lubricant film formation in hip joint replacements
Švachová, Michaela ; Dzimko, Marián (referee) ; Nečas, David (advisor)
This diploma thesis deals with an experimental analysis of lubricant film formation in hip joint replacements. The main objective is to clarify the effect of mean speed, slide-to-roll ratio, and material of femoral head on the development of film thickness, focusing on the role of particular constituents contained in model synovial fluid, such as albumin and -globulin. For this purpose, a model ball-on-disc configuration was applied, while the development of lubricant film was evaluated using the combination of fluorescent microscopy and optical interferometry. To better understand the process, coefficient of friction between implant surfaces was later investigated as well. The effect of material, slide-to-roll ratio, mean speed and model fluid composition was analysed. Results indicate that the main parameter, influencing the character of film formation, is slide-to-roll ratio. Under most conditions, the dominant constituent responsible for the film thickness development was albumin. Coefficient of friction is affected mainly by the material of implant. The thesis contains original scientific results extending the knowledge in the area of hip joint biotribology.
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Study of Friction in Hip Joint Replacements
Balounová, Hana ; Dzimko, Marián (referee) ; Vrbka, Martin (advisor)
Diploma thesis deals with analysis of coefficient of friction in total hip prosthesis for several materials bearing with presence of bovine serum as substitute of synovial fluid occurred in natural joint. Behavior of coefficient of friction is observed on Mini Traction Machine. Results are plotted at graphs representing dependence of coefficient of friction on time. There are described effects of several kinematic conditions, the influence of used material and the effect of the method of contact lubrication. The experiments analyze how the formation of lubricant film with a layer of adsorbed protein affects coefficient of friction.
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Mapping of lubricating film thickness of human big joints replacements
Bosák, Dalibor ; Hartl, Martin (referee) ; Vrbka, Martin (advisor)
This master’s thesis describes mechanism of lubricating film forming and its thickness in contact of a metal hip joint ball and a glass disc with chromium layer with presence of bovine serum as substitute of synovial fluid occured in a natural joint. Lubricating film thickness is evaluated by a thin film colorimetric interferometry, results are ploted at graphs representing dependence of lubricating film thickness on experiment duration or on mutual speed of articulating surfaces. There is described the influence of concentration of bovine serum and different kinematic conditions on lubricating film forming. From observed interferograms is apparent the adsorption of proteins to glass disc and femoral head surfaces, denaturation and formation of protein aggregations affecting the residual lubricating film thickness.
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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.
|
|
|
Experimental analysis of lubricant film formation in hip joint replacements
Švachová, Michaela ; Dzimko, Marián (referee) ; Nečas, David (advisor)
This diploma thesis deals with an experimental analysis of lubricant film formation in hip joint replacements. The main objective is to clarify the effect of mean speed, slide-to-roll ratio, and material of femoral head on the development of film thickness, focusing on the role of particular constituents contained in model synovial fluid, such as albumin and -globulin. For this purpose, a model ball-on-disc configuration was applied, while the development of lubricant film was evaluated using the combination of fluorescent microscopy and optical interferometry. To better understand the process, coefficient of friction between implant surfaces was later investigated as well. The effect of material, slide-to-roll ratio, mean speed and model fluid composition was analysed. Results indicate that the main parameter, influencing the character of film formation, is slide-to-roll ratio. Under most conditions, the dominant constituent responsible for the film thickness development was albumin. Coefficient of friction is affected mainly by the material of implant. The thesis contains original scientific results extending the knowledge in the area of hip joint biotribology.
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|
|
Effect of femoral head size on friction and lubrication in THR
Bartošík, Jan ; Dzimko, Marián (referee) ; Vrbka, Martin (advisor)
This diploma thesis concerns itself with the experimental study of friction and lubrication in the artificial hip joint depending on the head size. Measurements were made in a hip joint simulator based on the principle of pendulum. For the friction measurements artificial joints, made from three material combinations and two diameters, from two companies were used. The measurements show that the material combination has a more significant effect to friction coefficient than the head size. Using a bigger head size shows a decrease in friction coefficient for all material combinations when compared to a smaller head size. For the measurement of lubrication film the colorimetric interferometry was applied. A metal-on-glass contact pair was used, where the glass cups were made according to the real measurements of the joint cups. Four types of hip replacements with diameters of 28 and 36 mm with two different diametral clearance were measured during a constant motion of 210 seconds. Measurements show, that the lubrication film in the hip joint with a small diametral clearance increases very fast over the 800 nm value. Contact surfaces in the hip joint with a large diametral clearance aren’t separated by the lubrication film, resulting in a damage of the chromium coating in cup. A thick lubrication film results in a higher friction coefficient, when compared with hip joints with a very thin or no lubrication film.
|
|
|
Study of Friction in Hip Joint Replacements
Balounová, Hana ; Dzimko, Marián (referee) ; Vrbka, Martin (advisor)
Diploma thesis deals with analysis of coefficient of friction in total hip prosthesis for several materials bearing with presence of bovine serum as substitute of synovial fluid occurred in natural joint. Behavior of coefficient of friction is observed on Mini Traction Machine. Results are plotted at graphs representing dependence of coefficient of friction on time. There are described effects of several kinematic conditions, the influence of used material and the effect of the method of contact lubrication. The experiments analyze how the formation of lubricant film with a layer of adsorbed protein affects coefficient of friction.
|
|
|
Mapping of lubricating film thickness of human big joints replacements
Bosák, Dalibor ; Hartl, Martin (referee) ; Vrbka, Martin (advisor)
This master’s thesis describes mechanism of lubricating film forming and its thickness in contact of a metal hip joint ball and a glass disc with chromium layer with presence of bovine serum as substitute of synovial fluid occured in a natural joint. Lubricating film thickness is evaluated by a thin film colorimetric interferometry, results are ploted at graphs representing dependence of lubricating film thickness on experiment duration or on mutual speed of articulating surfaces. There is described the influence of concentration of bovine serum and different kinematic conditions on lubricating film forming. From observed interferograms is apparent the adsorption of proteins to glass disc and femoral head surfaces, denaturation and formation of protein aggregations affecting the residual lubricating film thickness.
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