Rozprawy doktorskie na temat „Total Knee Replacement (TKR) Implant”

Tato práce se zabývá pokročilou technologií výroby personalizovaných kloubních implantátů metodou EBM za použití titanové slitiny Ti6Al4V-ELI a navrhuje nový unikátní design kolenního implantátu společně s metodologií jeho inserce, přičemž tato řešení jsou součástí patentové přihlášky č. PV 2020-459. Toto neinvazivní řešení náhrady kolenního kloubu je šetrnější k pacientovi, maximálně chrání jeho zdravé tkáně a kosti, navíc se dá předpokládat vyšší životnost implantátu ve srovnání s tradičními dostupnými řešeními. Byla uskutečněna výroba vzorků z materiálu Ti6Al4V-ELI metodou EBM, proveden rozbor jejich materiálových, mechanických, technologických a únavových vlastností. Dále byly popsány pokročilé metody zobrazování, úpravy a tvorby kloubních ploch a použity k vyvinutí nového designu personalizovaného kloubního implantátu společně s inovační technologií jeho inserce a nástroji potřebnými k její úspěšné realizaci. Toto nové řešení bylo úspěšně ověřeno mnoha testy i výrobou Ti6Al4V-ELI a CoCrMo prototypů implantátů metodou EBM. Proveditelnost a použití v praxi bylo konzultováno a schváleno odborníky v této oblasti.

Little is known about time to return to work (TRTW) following planned medical events. This study was a secondary analysis (n=94) to determine predictors of time to return to work following a total knee replacement for osteoarthritis. Significant predictors of delayed TRTW following a knee replacement: 1) use of workplace modifications (in 6wks vs 5 wks) and 2) poor physical function (in 7wks vs 6 wks). These findings have large implications for workers undergoing knee replacement, orthopedic clinicians, and occupational health nurses.

La pose d’une prothèse totale de genou (PTG) se fait selon la technique d’alignement mécanique (AM) qui corrige les déformations constitutionnelles du membre pour créer un membre rectiligne. La survie à long terme des implants est excellente mais les résultats fonctionnels sont décevants avec notamment de nombreux symptômes résiduels. Une nouvelle technique chirurgicale, l’alignement cinématique (AC), vise à rétablir l’anatomie constitutionnelle pré-arthrosique du genou, et permet une amélioration des résultats fonctionnels des PTG. Cette technique est actuellement réalisée avec des implants destinés à un positionnement mécanique, et qui ont un design trochléen ne reproduisant pas l'anatomie trochléaire native. Ceci pourrait affecter la biomécanique de l’articulation patello-fémorale et donc rendre les résultats fonctionnels des PTG cinématiques non optimal. Ce travail vise à démontrer 1) les limitations de la technique mécanique, 2) la fiabilité de la technique cinématique pour le positionnement de l’implant fémoral, et 3) que les implants actuels ne permettent pas une restauration de l’anatomie trochléenne des patients
The conventional technique for TKA, namely mechanical alignment (MA), does not preserve the constitutional limb anatomy but systematically creates a straight limb. Excellent long-term implant survivorship has been reported, but functional outcomes are disappointing. To solve this problem, an alternative technique for TKA, namely kinematic alignment (KA), has recently been promoted and aims at restoring the constitutional (pre-arthritic) knee anatomy and laxity. Mid-term outcomes have shown excellent functional outcomes with this new KA technique. However, KA technique is currently done with TKA implants designed to be mechanically inserted. Their trochlea design does not reproduce the native trochlear anatomy, which could lead to increased rate of patellar complications with KA TKA. This work aims at demonstrating technical limitations of MA technique, good reproducibility of KA technique, and inappropriateness of current implant to restore patient trochlea anatomy

La gonarthrose est une maladie handicapante qui touche l’ensemble des structures articulaires du genou. Elle est favorisée par un défaut d’alignement du genou sur l’axe mécanique du membre inférieur, ce défaut cause un déséquilibre de la répartition des charges entre la partie médiale et la partie latérale de l’articulation. Lorsque la gonarthrose est trop avancée, une opération chirurgicale, l’arthroplastie totale de genou (ATG), permet le remplacement de l’articulation native par une prothèse totale de genou (PTG). Il n’y a pas de consensus clinique sur le meilleur positionnement des implants de la PTG, les principales causes d’échecs sont le descellement aseptique de l’implant tibial et les douleurs inexpliquées. Ces causes s'expliquent en partie par la perturbation du chargement mécanique de l’os induite par l’implantation d’une prothèse. Ce travail propose une méthode pour déterminer un positionnement des implants spécifique au patient pour limiter ces risques d’échec. Des méthodes automatiques, opérateur-indépendantes, d’association de repères anatomiques aux os du genou ont été développées et évaluées, elles permettent une implantation virtuelle automatique des implants. Nous avons montré que le défaut d’alignement conditionne les propriétés micromécaniques et micro-architecturales de l’os situé sous l’implant. Des modèles éléments-finis patients spécifiques ont été automatiquement construis. Pour chaque patient plusieurs stratégies chirurgicales de positionnement des implants ont été simulées et ont montré que le positionnement et les propriétés mécaniques de l’os trabéculaire influencent les phénomènes à l’origine d’une partie des échecs de PTG
Gonarthrosis is a widespread disabling disease which affects all joint structures of the knee. It is worsened by a non-alignment of the knee on the mechanical axis of the lower limb, this malalignment causes an imbalance in the distribution of loads between the medial and lateral part of the joint. When the gonarthrosis is too advanced, Total Knee Arthroplasty (TKA), allows the replacement of the native joint with a Total Knee Replacement (TKR) prosthesis. There is no clinical consensus on the best positioning of TKR implants, the main causes of failure are aseptic loosening of the tibial implant and unexplained pain. These causes are partly explained by the disruption of the mechanical loading of the bone induced by the implantation of a prosthesis. This work proposes a method to determine a patient-specific implant positioning to limit these risks of failure. During this thesis, operator-independent methods were developed and evaluated to automatically construct anatomical coordinate system on the knee bones, allowing automatic and parametric virtual implantation of implants. Using microindentation and µ-CT imaging, we showed that malalignment affects the micromechanical and micro-architectural properties of the bone under the implant. Patient-specific finite-element models were automatically built. For each patient, several surgical strategies for implant positioning were simulated. These simulations have shown that the positioning and mechanicals properties of trabecular bone influence the phenomena which cause a large part of TKR failure. The work carried out led to a numerical and mechanical method for optimizing the positioning of each patient's tibial implant

In the present work, experimental and numerical investigations into the load-displacement responses of a human lumbar Truncated Vertebral Unit (TVU) under quasi-static and impact loading conditions have been carried out for aiding in the design of orthopaedic implants and countermeasures for vehicle occupant and pedestrian safety. TVU samples obtained from the lumbar spinal column of an adult human male cadaver were initially subjected to quasi-static compressive tests. Impact tests were then conducted on a similar TVU sample in a drop-weight testing device instrumented with a piezoelectric load cell and a high-speed data acquisition system. An explicit nonlinear finite element model of the TVU was developed for predicting the experimental quasi-static and impact dynamic responses. Using the validated modelling approach mentioned, insights have been generated on adjoining vertebral stresses due to disc arthroplasty, and single and multi-level disc fusions as well as posterior fusions with and without posterior instrumentation. The numerical study is further extended to another crucial orthopaedic domain i.e. the assessment of the performance of variants of TKR (Total Knee Replacement) implants under ISO-specified dynamic gait cycle. In the latter investigation, a detailed and realistic finite element model of a representative human knee complex was developed by capturing relevant tissues such as femoral and tibial bones, medial and lateral collateral ligaments, and the components of a typical TKR implant including femoral component, tibial tray and UHMWPE (Ultra High Molecular Weight Polyethylene) insert. Substantive contribution has been made in the current research work towards assessment of vehicle occupant and pedestrian safety by applying the previously mentioned advanced finite element modelling approaches for representing complex vehicle structures, anthropomorphic test devices (commonly called as “dummies”), and pedestrian leg-forms. To this end, keeping in mind computational efficiency and need for optimization, a truncated finite element modelling approach capable of predicting the occupant response for a passenger car subject to a full-frontal US-NCAP test has been developed. Using the modelling tools mentioned and a nonlinear explicit LS-DYNA solver, it has been shown that meeting pedestrian safety standards need not be an isolated exercise of designing the front bumper of a vehicle only but can be combined with meeting NCAP occupant safety requirements leading to weight reduction of the front structure of a vehicle with gages of parts such as front rails in addition to bumper parts being included as design variables. For the first time, with the help of a comparative study carried out with a Hybrid 3 dummy and detailed biomechanical models of human lower extremity, the susceptibility of knees with TKR implants to periprosthetic injuries during frontal collisions has been demonstrated pointing out to a need for higher knee-protection countermeasures in vehicles.

Total knee joint replacements (TKRs) are a commonly used treatment when joint pain becomes a major issue and the function of activities of daily living is impaired. TKRs may last for up to 20 years; however, younger and physically more active patients are receiving TKRs, necessitating increased prosthesis life-time. There has been considerable interest in more cartilage-like materials for the tibial inlay of a TKR. Compliant, rubbery polymers may be a first step towards such a material. In this thesis, finite element analysis (FEA) was utilized to assess the feasibility of polycarbonate urethane (PCU) in a TKR application. Mechanical characterisation of PCU55D and PCU80A was performed in order to better understand the deformation behaviour of these materials. Mechanical test data was then used to tune and validate a hyperelastic material model. In a last step, the material model was applied to a static FE knee model which was used to simulate five discrete loading cases: three gait cycle events, stair climbing and squatting. Contact pressure, contact area and von Mises stress of the PCU inlay were compared to literature and to a standard ultra-high molecular weight polyethylene (UHMWPE) inlay. The contact area of the articulating implant surfaces was on average 345% greater in PCU than in UHMWPE and contact pressure was on average 77% lower in PCU than in UHMWPE. The difference between TKRs simulated with a PCU tibial inlay and those simulated with a UHMWPE inlay increased with increasing flexion angle. The contact pressures measured in TKRs simulated with a PCU tibial inlay were well below values that are expected to cause damage to the polymer, possibly reducing the risk of wear. The contact areas found in TKRs simulated with a PCU tibial inlay were close to what has been reported for the natural knee. Considering the low contact pressures even at high flexion angles, where initial congruency is limited, it may be feasible to design less conforming knee prostheses that still exhibit low contact pressures, allowing for a greater range of motion. The reported results strongly indicate that compliant polymers may offer an opportunity to improve current TKRs.
Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-08-11 14:59:50.801

碩士
東海大學
工業工程與經營資訊學系
105
Total Knee Replacement is an effective method for the treatment of severe osteoarthritis disease. The Taiwan National Health Insurance statistics show there are around 20,000 patients accepted the operation each year. The preoperative planning of TKR is to measure the size of patients’ knee by x-ray or computer tomography, etc. But, both of them are not able to accurately predict the size of patients' knees. This study implements gender, height, weight, age and the size of knee joint supplies to predict the size of a patient’s knee. Thereafter, it can reduce the size of supplies and the cost of medical expenses. The results show that there is a linear relationship among gender, height, weight, age and patitnts’ size. The linear regression model is capable of appling to predict the size of TKR.

It has been noticed that the need for total knee replacement surgery is increasing for Asian region. A total knee replacement is a permanent surgical solution for a patient having debilitating pain in knee joint suffering from arthritis. In this surgery, knee joint is replaced with components made up of bio-compatible materials after which the patient can resume the normal day to day activities. Western population has bigger build compared to Asian population. Most of the total knee replacement prosthesis are designed for western population. When these total knee prosthesis are used for Asian population, they cause a mismatch leading to various clinical complications such as reduced range of motion and pain. The studies have been limited to clinical complications caused by the mismatch. To address this limitation, current study is aimed to find the mechanical implications such as stress distribution, maximum stresses, maximum displacements etc., caused by mismatch of total knee replacement components with knee. A surgeon selects total knee components for a patient based on some critical dimensions of femur and tibia bone of knee. In addition, a method to accurately calculate these dimensions of the femur and tibia bone of a real knee was developed in the current study. This method calculated the points of curvature greater than a threshold (decided based on the radius of the curvature) found out using the formula of curvature. Further, the highest point was calculated based on maximum height from a line drawn between initial and final point within the captured points, also the extreme points were calculated based on the sign change in slope of points within the captured points, giving multiple points on the boundary of bones extracted in an MRI image of a patient. The distance between two selected farthest points, out of these points, in specific direction was the basis for selection of the TKR components. Total knee replacement components were modeled in Geomatics Studio 12 software, bones were modeled in Rhinoceros 5 software, assembly of bones and total knee replacements components was done in Solid works 2013 software, the finite element model of the assembly was developed in Hyper mesh 11 software and, the stress analysis and post processing was done in ABAQUS 6.13 software. A static, implicit non linear analysis was performed. Simulations were performed for two conditions: at standing (0o of flexion) and at hyper-flexed (120o of flexion). In order to figure out if there were any mechanical implications of mismatch, the full model of assembly consisting of femur, tibia and fibula bones assembled with total knee replacement components, and the reduced model consisting of only total knee replacement components were simulated separately, results of which have been discussed in the current thesis. In this work, the effect of change of length of ligaments at 120o of flexion in detail was also studied. This study brought out various outcomes of contact mechanics and kinematics between the components of total knee replacement prosthesis.

It has been noticed that the need for total knee replacement surgery is increasing for Asian region. A total knee replacement is a permanent surgical solution for a patient having debilitating pain in knee joint suffering from arthritis. In this surgery, knee joint is replaced with components made up of bio-compatible materials after which the patient can resume the normal day to day activities. Western population has bigger build compared to Asian population. Most of the total knee replacement prosthesis are designed for western population. When these total knee prosthesis are used for Asian population, they cause a mismatch leading to various clinical complications such as reduced range of motion and pain. The studies have been limited to clinical complications caused by the mismatch. To address this limitation, current study is aimed to find the mechanical implications such as stress distribution, maximum stresses, maximum displacements etc., caused by mismatch of total knee replacement components with knee. A surgeon selects total knee components for a patient based on some critical dimensions of femur and tibia bone of knee. In addition, a method to accurately calculate these dimensions of the femur and tibia bone of a real knee was developed in the current study. This method calculated the points of curvature greater than a threshold (decided based on the radius of the curvature) found out using the formula of curvature. Further, the highest point was calculated based on maximum height from a line drawn between initial and final point within the captured points, also the extreme points were calculated based on the sign change in slope of points within the captured points, giving multiple points on the boundary of bones extracted in an MRI image of a patient. The distance between two selected farthest points, out of these points, in specific direction was the basis for selection of the TKR components. Total knee replacement components were modeled in Geomatics Studio 12 software, bones were modeled in Rhinoceros 5 software, assembly of bones and total knee replacements components was done in Solid works 2013 software, the finite element model of the assembly was developed in Hyper mesh 11 software and, the stress analysis and post processing was done in ABAQUS 6.13 software. A static, implicit non linear analysis was performed. Simulations were performed for two conditions: at standing (0o of flexion) and at hyper-flexed (120o of flexion). In order to figure out if there were any mechanical implications of mismatch, the full model of assembly consisting of femur, tibia and fibula bones assembled with total knee replacement components, and the reduced model consisting of only total knee replacement components were simulated separately, results of which have been discussed in the current thesis. In this work, the effect of change of length of ligaments at 120o of flexion in detail was also studied. This study brought out various outcomes of contact mechanics and kinematics between the components of total knee replacement prosthesis.

Total knee replacement is the gold standard treatment for restoring mobility and relieving pain associated with osteoarthritis when other medical therapy has failed. Revision surgery is necessary when the replaced knee fails, which is often a result of implant damage (such as wear) or poor kinematics. Design optimization is a method for finding the best shape for a component using an optimization approach considering one or multiple performance metrics. The shape of a parametric candidate design can be manipulated by an optimization algorithm, which seeks to minimize an objective function subject to performance constraints and design space limitations. During multiobjective design optimization, multiple performance measures are minimized simultaneously, the relative importance of each determined using a weighted sum. This approach can also be used to derive a Pareto curve or frontier which graphically describes the relationships (or trade-offs) between the performance measures. It was hypothesized that a trade-off exists between wear and kinematics performance in total knee replacements. The objective of this research was to test this hypothesis by using multiobjective design optimization to describe this relationship with a Pareto curve. It was first necessary to develop and validate numerical frameworks for wear and kinematics simulations, using models constructed using a parametric modeller. The Pareto curve was then generated using a combination of single objective and multiobjective design optimizations considering these two performance measures. Single objective optimization for wear yielded a theoretical design with superior wear resistance when compared to a typical commercially available knee design. Single objective optimization for kinematics yielded a theoretical design capable of higher flexion, as well as more natural laxity characteristics. After performing multiobjective design optimization, the resulting Pareto curve showed that there is, in fact, a trade-off between wear and kinematics performance. When considering optimum designs, in order to improve the wear performance it was necessary to sacrifice kinematics performance, and vice-versa. This previously suspected but never verified nor quantified relationship can be used to improve total knee replacement designs, as well as help healthcare providers select the best implants for their patients.
Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2010-04-14 13:43:42.639

Epidural analgesia causes a temporary cessation of nerve conduction via administration of low concentration of local anaesthesia, or opioid, into epidural space. The resulting temporary discontinuation of nerve conduction is called central neuroaxial anaesthesia and it facilitates the process of surgical intervention. An epidural catheter is usually inserted during epidural desensitisation. It helps to control the amount of administered anaesthesia and hence to respond to surgery progress, but it also enables to keep the catheter within the epidural space for the following postoperative analgesia, which will promote timely postoperative rehabilitation and pain management.The research project was conducted on basis of quantitative and qualitative investigation. The quantitative research was performed via questionnaires directed at the nursing staff, and the qualitative research took form of semi-structured interviews with patients. The quantitative investigation was conducted in fourteen health care facilities in the Czech Republic. Respondents of the quantitative research were nurses working in orthopaedic departments, multidisciplinary ICU or ARO (Anaesthesiology Resuscitation Dept.), who provided care to patients after TKR or THR with an epidural catheter insitu. Qualitative research respondents were patients hospitalised in orthopaedic departments for TKR or THR, with epidural catheter insitu and who agreed to participate at the interview. Quantitative research data were processed in Excel 2010 and presented in graphs, frequency and contingency tables, whereas the qualitative research data were processed using charts of the Smart Art program. After the agreement with the management of health care facilities, this dissertation will promote education and aid situation improvement. The Standard of Nursing Care Assisting a Patient with Epidural Catheter during Insertion and Care will be an outcome of this project. Moreover, we will design a patient information booklet and a quality of care indicator that will focus on monitoring of complications occurrence such as infections in patients with epidural catheter. The findings may help to design a training course specialised in nursing care provision to those patients and also to provide basis for further research.