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Mechanical Analysis of the Influence of Fabrication Tolerances on Contact Conditions between the Acetabular Cup and the Femoral Head in Total Hip Replacement
Koukal, Milan ; Horyl, Petr (referee) ; Repko, Martin (referee) ; Janíček, Přemysl (referee) ; Florian, Zdeněk (advisor)
In endoprosthesis surgery there are typically a high percentage of implant defects, these can lead to failure of the whole prosthesis. One type of total hip replacement function loss is acetabular cup loosening from the pelvic bone. This disertation examines manufacture perturbations as one of the possible reasons for this kind of failure. Both dimension and geometry manufacturing perturbations of ceramic head and polyethylen cup were analyzed. We find that perturbations in the variables analysed here affect considered values of contact pressure and frictional moment. Furthermore, contact pressure and frictional moment are quantities affecting replacement success and durability. From obtained results it can be recommended to fit head and cup with a clearance of between 0 mm and 0.05 mm. It can not be recommend using interference type of fit because of strong deterioration of the contact conditions. Roundness perturbation of ceramic head should not exceed 0.025 mm.
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Stress - strain analysis of total hip replacement - type Santori
Huťka, Pavel ; Fuis, Vladimír (referee) ; Florian, Zdeněk (advisor)
Submitted Diploma thesis deals with stress-strain analysis of deformation proximal end of femur with applied total hip joint endoprosthesis (replacement) – shortcut type. To identify deformation and tensity (stress) was used computational simulation by method of final elements. Have been created two computational models TEP- type Santori and type DePuy Proxima. Geometry model Santori was created on low level model geometry through the use of X-ray photograph. Principle of geometry model type DePuy Proxima was real Femoral stem endoprosthesis which was scanned on scanner ATOS. Geometry of both these replacements were set up in program Rhinoceros 4.0 and then execute in program CatiaV5R17. Data for geometry model of femur were gained from CT chains. Material model of femur have been crated in two variants. The first one looks at structure bone tissues and the second one were created by Gruen´s zones. Femoral Stem was weighted by static equivalent resultant force acting in hip joint. Computational model of system and self solution, including depiction results, was done by ANSYS Workbench 11.0 for four model variants.
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Experimental study of friction and lubrication in THR
Urban, Filip ; Čermák, Jan (referee) ; Vrbka, Martin (advisor)
This work analyzes problems of friction and lubrication of total hip replacement (THR). At first, experimental study of friction coefficient under various conditions was conducted using hip joint simulator based on principle of pendulum. After that, lubrication film development was observed, using colorimetric interferometry with head from THR and glass cup with respect of geometry and clearance to cups made originally for THR. With respect to research study [25] it was found that increasing contact conformity leads to increased film thickness. Also protein adsorption on articulating surfaces was observed. Thanks to adsorption 80 nm film thickness was measured even if relative surface speed was zero. Furthermore protein aggregation was observed on the border of contact zone, similar aggregations were observed by Myant et al. [29] or Vrbka et al. [25]. These aggregations are formed when lubricant is under shear stress and it can positively affect film thickness. If the relative motion of articulating surfaces is not sufficient, the protein layer can`t be refreshed enough and film thickness start decreasing. Coefficient of friction 0,13 was measured when lubricating film development was observed. Close to this value are material combinations metal on polyethylene and metal on metal.
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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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History of hip joint replacements
Kohout, Jiří ; Urban, Filip (referee) ; Vrbka, Martin (advisor)
In this bachelor´s thesis is solved problem of friction, lubrication, wear and history of hip replacement. History is described from the second half of 18th century and there was an effort to include every important milestones that affected development of the alloplastic of hip joint. Beside this development is also observed volume wear of hip joint. History of lubrication and friction is watched from first experiment, which measured these factors it means mid-20th century.
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VOLUMETRIC WEAR ANALYSIS OF HIP JOINT IMPLANTS BY OPTICAL METHODS
Ranuša, Matúš ; Bryant, Dr Michael (referee) ; Dr Prashant K. Sharma (referee) ; Vrbka, Martin (advisor)
Predložená dizertačná práca sa zaoberá analýzou opotrebenia totálnych bedrových endoprotéz za použitia optických metód. V práci bol predstavený nový prístup hodnotenia objemového úbytku materiálu pomocou 3D optického skeneru. Tento nový prístup je časovo efektívny, poskytuje veľké množstvo snímaných bodov na povrchu implantátu. Množstvo bodov umožňuje presnejšiu rekonštrukciu pôvodnej geometrie a prípadné rekonštrukcie nežiaducich poškodení polyetylénovej vložky pri extrakcii. Predstavené metóda bola validovaná za pomoci štandardizovanej gravimetrickej metódy v súlade s ISO 14242. Následne bol optická skenovacia metóda použitá v troch štúdiách zameraných na analýzu opotrebenia, mechanické zmeny artikulujúceho povrchu a mikroštruktúrne zmeny v dôsledku zlyhania implantátu. Analýza 23 extrahovaných polyetylénových vložiek typ Bicon - plus s rozšíreným použitím v Českej republike poukázala na niektoré problémy spojené so zlyhaním implantátu. Adhezívno - abrazívne opotrebenie bolo identifikované v oblasti penetrácie femurálnej hlavice a následné poškodenia ako delaminácia materiálu , plastické deformácie a pitting boli pozorované v okolí tejto oblasti. Analýza materiálových vlastností poukázala na degradáciu mechanických a chemických vlastností, čo bolo prevažne závislé od rozsahu opotrebenia implantátu. U implantátov boli pozorované výrazné plastické deformácie , nárast oxidačného indexu a nižší pomer tvrdosti voči modulu elasticity, v porovnaní s novými vzorkami. Tečenie materiálu a plastické deformácie, ktoré vykazovali všetky extrahované vzorky boli analyzované v závere predloženej dizertačnej práce, na základe testov na nových implantátoch v zábehovom cykle. Cieľom práce je uviesť nový prístup analýzy opotrebenia polyetylénových vložiek za pomoci optických skenovacích metód a preukázať jeho použiteľnosť na analýze súboru extrahovaných implantátov. Výsledky získané pomocou tejto metódy sa ukázali ako vhodné a môžu viesť k lepšiemu pochopeniu procesov opotrebenia a zlyhávania implantátov.
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Case study of physiotherapy care of a patient with rheumatoid arthritis and after hip replacement surgery
Páleníková, Vanda ; Pavlů, Dagmar (advisor) ; Jarošová, Hana (referee)
Title: Case study of physiotherapy care of a patient with rheumatoid arthritis and after hip replacement surgery Author: Vanda Páleníková Aim: Summary of theoretical knowledge, performing a kinesiological analysis, design treatment and monitoring of the patient during rheumatoid arthritis, and before and after right hip replacement surgery and subsequently summation effects by therapy. Methods and abstract: This thesis was created during professional practice, which was held at the Institute of Rheumatology in Prague from 14.1. 2013 to 8.2 2013. The thesis is divided into two parts - general and special. The first (general) part deals with the theoretical knowledge of rheumatic diseases, particularly rheumatoid arthritis and hip replacement surgery and methods of treatment, including physiotherapy practice. The second (special) case report describes a patient with rheumatoid arthritis before and after total hip replacement surgery, the design and the process of therapy and its evaluation. Result: The patient's condition was improved. After the operation has been modified posture and position in right hip joint. During therapy increased muscle strength and increase range of motion in the right hip joint. Key words: case study, rheumatoid arthritis, total hip replacement, surgery of rheumatic...
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Case Study of Physiotherapy Treatment of a Patient with Diagnosis after total hip arthroplasty
Záhorová, Lucie ; Neuwirthová, Svatava (advisor) ; Novotná, Irena (referee)
Author: Lucie Záhorová Supervisor: Mgr. Svatava Neuwirthová Title: Case Study of Physiotherapy Treatment of Patient after total hip arthroplasty Objectives: The aim of this thesis is a case study of physiotherapeutic care of a patient after total hip arthroplasty, evaluation of the effect of therapy and theoretical treatment of this diagnosis. Methods: The bachelor thesis consists of a general part, which uses the literature to discuss the topic of total hip arthroplasty, and a special part, which contains a case report of a patient with this diagnosis. The special part includes a comprehensive initial kinesiological examination, description of the individual therapeutic units, an output kinesiological examination and an evaluation of the effect of therapy. Results: The final kinesiological examination confirmed that the therapies had a positive effect on the patient's health. The greatest improvement is seen in the increase in muscle strength in the right hip joint and the increase in range of motion. Another improvement is the reduction of swelling and the effect on the shortened muscles. These results prove that the therapies were effective. Conclusion: During the rehabilitation program, which lasted two weeks, the patient attended a total of eight therapies. At the end, an outcome...
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Case report of a patient after total hip arthroplasty
Velechovský, Michal ; Sohrová, Jana (advisor) ; Neuwirthová, Svatava (referee)
Title: Case report of a patient after total hip arthroplasty Objectives: The aim of this case study is to obtain and elaborate the current knowledge about the diagnosis of total hip arthroplasty. In the special part, the aim is to elaborate a case study of a patient after total hip arthroplasty with the proposal of therapy, its implementation and evaluation of the results. Methods: This case study is divided into two parts, theoretical and practical. The theoretical part contains the current knowledge related to the diagnosis of total hip arthroplasty, including anatomy, kinesiology, the operation itself, preoperative rehabilitation and postoperative rehabilitation. The practical part includes the analysis of a specific case of a patient after total hip arthroplasty and includes the initial kinesiological analysis, the course of therapy and the outcome kinesiological analysis with the evaluation of therapy. Results: After almost three weeks of rehabilitation in the Rehabilitation Hospital Beroun, the patient's subjective and objective condition improved, her pain was eliminated and her joint range and muscle strength were increased. Keywords: hip joint, total hip replacement, physiotherapy, rehabilitation, case study
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