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Development of the coefficient of friction and lubrication film in a total knee replacement during a gait cycle
Odehnal, Lukáš ; Horák, Zdeněk (referee) ; Ranuša, Matúš (advisor)
This master´s thesis deals with the experimental analysis of the coefficient of friction and lubrication film in total knee replacement. The experiments are performed on a knee joint simulator, with an implemented module for measuring friction. To observe film formation, fluorescent microscopy is used. The experiments are mainly focused on a detailed description of the influence of parameters occurring during the gait cycle. This approach should significantly help in describing the tribological processes that occur in the total knee replacement. The results confirm previous investigations in terms of axial load, where the coefficient of friction decreases with the increasing load. In the case of lubrication film, no significant changes are observed. On the contrary, while investigating the influence of SRR, noticeable changes in film formation are observed while the coefficient of friction being unaffected. While describing the whole gait cycle, precise results are obtained only in the first half of the cycle as the second half is accompanied by the occurrence of large deviations from a rapid decrease of load. This work provides a better understanding of the field of lubrication film in total knee replacements. Moreover, thanks to the simultaneous measurement of the coefficient of friction and the observation of the contact area, it is possible to draw better conclusions than if the experiments had been carried out separately.
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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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Internet Used-Cars Shop
Horák, Zdeněk ; Jurka, Pavel (referee) ; Skřivánek, Roman (advisor)
This bachelor's thesis contains the analysis, the design and the information system implementation of the Internet used-cars shop. The system files predominantly information about the cars which the used-cars shop offers for sale. The system saves basic data about each car, the data about the former keeper, general information about the car producer and about the car price changes. Two kinds of users can log into the system with a specific password. The customer of the used-cars shop who is allowed to view the catalogue of offered cars and make a reservation. The second is the system administrator who can edit saved data. The used-cars shop forum is also available.
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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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Treatment of humeral diaphyseal fractures using Hackethals retrograde elastic nailing - a clinical and experimental verification of this method in contemporary traumatology
Obruba, Petr ; Džupa, Valér (advisor) ; Horák, Zdeněk (referee) ; Paša, Libor (referee)
Hackethal's bundle nailing of diaphyseal humeral fractures was historically reliable and cheap method, used for stabilization of simple humeral shaft fractures. After arrival of solid nails, this technique was successively abandoned, initially in Germany, followed by countries of Central Europe. Several cliniques are at present still using this technique successfully. Goal of this work was to establish, whether the declared stability of this technique is comparable to those of more evolved methods, whether this technique does not cause higher amount of complications, and to describe how the stability of nails bundle depends on number and diameter of used implants. The cost efficiency of different modern osteosynthetic methods used for stabilization of humeral shaft fractures was also analyzed. For verification of determined hypotheses, two clinical and one experimental studies were developed. First clinical study was focused on success rate of osteosynthesis and it's complications. In studied population of 50 patients, 4 of them (8%) developed a non-union, which was in all cases caused by wrong indication or technical error during implantation. Superficial infection was observed once, no deep infection had developed. Nine patients (18%) have healed in rotational or axial malalingement that had no...
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Supportless 3D print by 6-axis robotic arm
Krejčiřík, Petr ; Horák, Zdeněk (referee) ; Škaroupka, David (advisor)
This diploma thesis deals with the solution 3D printing by KUKA robotic arm without realization of supporting structures. The 6-axis KUKA KR 60HA robotic arm allows adjusting 3D printing strategies compared to classical 3D printing concept. The first part of the diploma thesis is about the identification of the current state of knowledge, especially the state of the experimental device for the robotic 3D print. To improve quality of the printed is necessary to modify the printing head and develop the suitable calibration principle. Special printing strategies were designed to rearch the 3D printing overhead volumes without creating support structure. A special alghoritm in the Grasshopper evnironment was developed for generating 3D print trajectory on the body surface. For the quality improvement it is necessary to optimize the process parameters. The final step is experimental 3D printing with the evaluation of surface dimensions, geometric precision and layer coherence in various printing strategies.
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Human locomotion after total hip replacement
Horáková, Alena ; Vilímek, Miloslav (advisor) ; Horák, Zdeněk (referee)
Title: Human locomotion after total hip replacement Objectives: The aim of this thesis is to perform a gait analysis of patients after total hip replacement and to find out, how chosen temporo-spatial, kinetic and kinematic parameters change during the first half a year after the surgery. The deviations found in gait stereotypes of individual patients are further compared with results of international studies. Methods: The thesis is theoretical-empirical, with small number of patients. 3D kinematic gait analysis was performed by Qualisys system and ground reaction forces by two Kistler force plates. The following parameters are being monitored: length of step, stance phase duration, cadence, walking speed, lateral shift of the pelvis and trunk in standing phase, contralateral pelvic drop in standing phase of the leg, maximum range of motion of the hip joint in sagital plain, maximum of vertical and medio-lateral component of the ground reaction forces in the standing phase. Results: The highest side deviations between legs were found in 3 months after the surgery and remained until 6,5 months after the surgery. In this time period a lower value of the length of step, stance phase duration, maximum range of motion of the hip joint in sagital plain and also a higher lateral shift of the pelvis was...
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Analysis of muscle activity during steering wheel movement
Dostálová, Veronika ; Vilímek, Miloslav (advisor) ; Horák, Zdeněk (referee)
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