PhD Fekete - SZIE version - 2.2 - Szent István Egyetem

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Literature review One possible interpretation of the difference in the actual and expected wear can be originated to the fact, that the sliding-rolling ratio is not correctly taken into account, or if it is possible to set on the test setup, than it is incorrectly adjusted to the motion. Laurent et al. [Laurent et al., 2003] also suggested that the wear mechanism is highly dependent not only on the loading of the connecting surfaces but the interfacial contact kinematics, which consist a cyclic multidirectional path of motion and the rolling-sliding ratio. However, how is the sliding-rolling ratio involved into tribological tests? A wear study on TKRs is carried out similarly as other wear tests. Load, number of cycles, in some studies sliding-rolling ratio and other factors, have to be set before the test and after the experiment, according to these parameters, wear can be estimated. However, while the load (which is represented as the tibiofemoral force between a femoral and tibial compartment) is a well-known parameter or at least the maximum of the load is known, the sliding-rolling ratio in the active functional arc (where most of the locomotion is carried out) is currently unknown. For this reason, this part of the thesis is dedicated to the sliding-rolling phenomenon of total knee replacements. With the obtained results, (minimum and maximum values of the ratio, evolution along the flexion angle) valuable information can be provided about this significantly influencing wear. The applied methods are numerical, since computer models proved to be useful tools for predicting human kinematics especially if the motion has to be modelled in three-dimension. In the followings, a review of different models (numerical and experimental) will be presented, while the second part of the study describes a new multibody model, which can estimate the sliding-rolling phenomenon and the kinetics between the contact surfaces (condyles) under squatting movement. – 52 –
2.3.2. General numerical models Literature review Although the knee is statically unstable structure, the surrounding ligaments, menisci, and muscles sustain its stability. In case of investigating local kinematics and/or kinetics of the knee joint, an adequately complex model has to be created. By importing realistic geometry of the condyles into a modelling software, muscle forces or contact pressures (in case of deformable bodies) can be predicted. Since computational models outnumber analytical models, only the most cited three-dimensional multibody and finite element models are summarized in Table 2.3. AUTHORS DYNAMIC / QUASI- MODEL TYPE CONTACT STATIC Wismans et al., 1980 Quasi-static Knee Rigid Blankevoort et al., 1991 Quasi-static Knee Deformable Pandy et al., 1997, 1998 Quasi-static Knee Deformable A-Rahmann and Hefzy, 1998 Quasi-static Knee Rigid Kwak et al., 2000 Quasi-static Knee Deformable Piazza and Delp, 2001 Dynamic Full-body Rigid Cohen et al., 2003 Quasi-static Knee Deformable Dhaher and Kahn, 2002 Quasi-static Knee Rigid Chao, 2003 Quasi-static Knee Deformable Guess et al., 2010 Dynamic Knee Deformable Bíró et al., 2010 Dynamic Knee Rigid Table 2.3. Numerical knee models It is clear from the table that both rigid- and deformable models are frequently used. Most of the cases, the authors were in agreement – as an adequate approximation – to model only the knee itself, not the complete leg or body. The rigid body models or multibody models generally lack the ability to calculate contact pressures, but have the advantage of providing precise contact definition, not only static but real dynamic simulation and quick iteration. On the other hand, finite element models, due to the considerable simulation time, are often used for static simulation but they offer more calculation options against the multibody models. 2.3.3. Sliding-rolling phenomenon – Numerical models In this subsection, a review has been assembled, similarly to the earlier section, where the early models are revised, highlighting their advantages, disadvantages and their results related to sliding-rolling. Compared to other questions, the sliding-rolling phenomenon, with regard to physiological knee joints or TKRs, earned the interest of lesser authors, which is apparent due to the low number of studies about this specific area. Van Eijden et al. [Van Eijden et al., 1986] constituted remarkably not only in the kinetics of the human knee joint, but also in the kinematics, by being the first ones who gave local description about the sliding-rolling phenomenon (denoted in their paper as rolling-gliding) between the femur and the patella (Figure 2.50). – 53 –
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SZENT ISTVÁN UNIVERSITY KINETICS A
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CONTENTS NOMENCLATURE AND ABBREVIAT
Page 5 and 6: NOMENCLATURE AND ABBREVIATIONS F pf
Page 7 and 8: ψ : Angle between the quadriceps t
Page 9 and 10: v CTt : Tangential velocity compone
Page 11 and 12: Introduction 1. INTRODUCTION AND OB
Page 13 and 14: 1.3. Aims of the PhD thesis Introdu
Page 15 and 16: Literature review 2. LITERATURE REV
Page 17 and 18: Literature review Figure 2.3. The f
Page 19 and 20: Literature review Figure 2.6. Patel
Page 21 and 22: Literature review Figure 2.8. Compo
Page 23 and 24: Literature review The knee carries
Page 25 and 26: Literature review For this reason,
Page 27 and 28: Literature review Figure 2.12. Thre
Page 29 and 30: Literature review As a short overvi
Page 31 and 32: Literature review Moment arm 60 [mm
Page 33 and 34: Literature review I. They demonstra
Page 35 and 36: Literature review The presented mod
Page 37 and 38: Literature review ε angle [˚] 100
Page 39 and 40: Literature review Fpf/Fq [-] 1.2 1
Page 41 and 42: Literature review β angle [˚] Mal
Page 43 and 44: Literature review Figure 2.35. Mech
Page 45 and 46: Literature review Moment arm 60 [mm
Page 47 and 48: Literature review Let us follow the
Page 49 and 50: Literature review Finally, the pate
Page 51 and 52: Literature review Figure 2.43. Tota
Page 53 and 54: Literature review One great advanta
Page 55: Literature review Implant wear is t
Page 59 and 60: a) The tibia plateau is a flat surf
Page 61 and 62: Literature review From their calcul
Page 63 and 64: Literature review Although a simila
Page 65 and 66: Literature review Slide/Roll [-] 1
Page 67 and 68: Literature review Figure 2.62. Mult
Page 69 and 70: Materials and Methods 3.1. Methodol
Page 71 and 72: Materials and Methods For the sake
Page 73 and 74: Materials and Methods 9 th QUESTION
Page 75 and 76: Materials and Methods 3.3. New anal
Page 77 and 78: Materials and Methods 3.3.3. Free-b
Page 79 and 80: Materials and Methods Figure 3.6. F
Page 81 and 82: Materials and Methods By the introd
Page 83 and 84: Materials and Methods 3.4. Experime
Page 85 and 86: Materials and Methods Figure 3.7. C
Page 87 and 88: Materials and Methods All of the pa
Page 89 and 90: Materials and Methods 3.4.5. Measur
Page 91 and 92: x c Materials and Methods ∑ Fi
Page 93 and 94: Materials and Methods Probability D
Page 95 and 96: Materials and Methods Figure 3.18.
Page 97 and 98: Materials and Methods By doing so,
Page 99 and 100: 3.4.7.2. Steps of the approach Mate
Page 101 and 102: Materials and Methods All the funct
Page 103 and 104: Materials and Methods β [º] 40 20
Page 105 and 106: Materials and Methods If the center
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Materials and Methods By the use of
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Materials and Methods Thus, one pri
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Materials and Methods I. The patter
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3.6.3. Geometrical models Materials
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Materials and Methods − − −
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3.6.4.3. Contact [MSC.ADAMS] Materi
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Materials and Methods Besides the k
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Materials and Methods By multiplyin
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Results 4. RESULTS 4.1. Results reg
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Results This closely equal percenta
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Results Fpf/BW [-] 8 Fekete et al.
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Results In reality, human subjects
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Results 4.2. Results regarding the
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Results 0.8 Χ [-] 1 Sliding-rollin
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Results Χ [-] 1 Sliding-rolling ra
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Results Among the tested prostheses
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Results χ [-] 1 Averaged sliding-r
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Results Χ [-] 1 Sliding-rolling ra
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4.3. New scientific results Results
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Results 3 rd Thesis: Based on the m
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Conclusions and Suggestions 5. CONC
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Conclusions and Suggestions Suggest
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Summary 6. SUMMARY In this doctoral
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Appendix APPENDIX A1. Bibliography
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Appendix [31] Csizmadia B. M., Nán
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Appendix [61] Gill H. S., O’Conno
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Appendix [93] Klebanov B. M., Barla
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Appendix [123] Nägerl H., Frosch K
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Appendix [154] Reuben J. D., McDona
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Appendix [187] Wahrenberg H., Lindb
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Appendix 6. Fekete G., Kátai L.: M
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Appendix Figure 3. Setting Stitchin
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Appendix Fpf/Fq [-] 1.2 h = 6 mm h
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Appendix η1 angle [˚] 6 Hirokawa
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Appendix Figure 13. Mechanical mode
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Appendix Ψ angle [˚] 10 Van Eijde
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Appendix Figure 19. Mechanical mode
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Appendix - 177 -
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PhD Fekete - SZIE version - 2.2 - Szent István Egyetem

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