<p>Musculoskeletal degradation and musculoskeletal injuries place a substantial burden on the healthcare system. Advancing the understanding and prevention of the injury potential associated with these injuries in various demographics as well as advancing performance optimization requires knowledge of the loading distribution among the various musculoskeletal tissues at the joints. Accurate muscle force estimates are needed for characterizing these distributions due to their influence on the loading of the system. This dissertation discusses</p> <p>the development and validation of a physiologically-driven skeletal muscle force model that is suitable for application on an individualized level. The derivation of the skeletal muscle force model began with dimensional analysis and a selection of critical parameters that define muscle force generation. One of the key parameters included was measured muscle voltage using electromyography sensors. This provided the model with the ability to be easily used</p> <p>in application-based studies. It also incorporated the muscle force-length, force-velocity, and force-frequency curves, providing an even stronger physiological basis to the model. Validation was performed by multiple studies using experimental data from subjects conducting exercises chosen to target specific muscles of interest. Data was collected from a Vicon Vero motion capture system, an instrumented Bertec treadmill, and Delsys Trigno electromyography sensors. The first study analyzed the ankle joint of seventeen subjects using the two Newton-Euler equations of rigid body motion and the skeletal muscle force model. The average percent error across all subjects was 8.2% and ranged from 4.2% to 15.5%. The second study analyzed the sensitivity of two sets of parameters within the model. The first was conducted on a set of observed and fitted constants from the dimensionless pi terms and aimed to identify which, if any, could be excluded from an optimization routine. Results indicated that only two of the nine constant parameters needed to be optimized. The second sensitivity analysis focused on the anatomical kinematic parameters in order to identify the impact that the incorporation of MRI scans for subject-specific anatomical models would have on the accuracy of the model’s output. Results demonstrated sensitivity to the muscle insertion points, suggesting that the use of MRI scans could increase the accuracy of the model. The third study was a case study focused on evaluating the assumption of a constant within the skeletal muscle force model remaining constant over time. Results indicated that the collection of maximum EMG recordings for these studies may not have been controlled to a desirable level and that the inclusion of specialized equipment for maximum EMG recordings would likely validate this assumption. The final study analyzed the</p> <p>knee joint of ten subjects in a similar fashion to that of the ankle joint. The goal was to observe the model’s performance on a more anatomically complex joint. The average percent error across all subjects was 20.6%, approximately two times higher than the ankle joint.</p> <p>However, the majority of the error associated with this study came from the deviation in calculated moments about an axis of much smaller importance and magnitude than the primary flexion/extension axis. When errors were excluded from this axis, the average percent error for all subjects was 8.8%, almost identical to that of the ankle joint application. These findings as a whole indicate that the model has predictive ability and is capable of providing reasonable estimates of both muscle forces and surrounding musculoskeletal tissue loading. Therefore, the model could be used in various biomechanical advancements and applications in injury prevention, performance optimization, tissue engineering, prosthetic design, and more.</p>

Articular cartilage is a specialized connective soft tissue that resides onthe ends of long-bones, transfers the load smoothly between the bones in diarthrodialjoints by providing almost frictionless, wear resistant sliding surfacesduring joint articulation. Focal chondral or osteochondral defects in articularcartilage are common and show limited capacity for biological repair. Furthermore,changes in the bio-mechanical forces at the defect site may makethe tissue more susceptible to continued degeneration. Alternatively, the contouredfocal resurfacing metal implant can be used to treat such full thicknesscartilage defects. Physiological and biomechanical studies on animal modelswith metal implant have shown good clinical outcomes. However, the mechanicalbehavior of cartilage surrounding the implant is not clearly known withrespect to the joint function after treating such defects with metal implantsand also to improve the implant design. We developed a simple 3-dimensionalfinite element model by approximating one of the condyles of the sheep kneejoint. Parametric study was conducted in the simulations to verify differentprofiles for the implant, positioning of the implant with respect to cartilagesurface, defect size and to show the mechanical sealing effect due to the wedgeshape of the implant. We found the maximal deformations, contact pressuresand stresses which constitute the mechanical behavior of cartilages. We alsoconfirmed that using a metal implant to fill the full thickness chondral defectsis more beneficial than to leave the defect untreated from mechanical point ofview. The implant should be positioned slightly sunk into the cartilage basedon the defect size, in order to avoid damage to the opposing surface. The largerthe defect size, the closer the implant should be to the flush. We also simulatedthe time dependent behavior of the cartilages. In all the simulations, a staticaxial loading was considered. The wedge shape of the implant provided themechanical sealing of the cartilage surrounding the implant. The determineddeformations in the cartilages immediately surrounding the implant are instrumentalin predicting the sticking-up of the implant into the joint cavity whichmay damage opposing soft tissues. / <p>QC 20101125</p>

The loss of mobility among the elderly has become a significant health and socio-economic concern worldwide. Poor mobility due to gradual deterioration of the musculoskeletal system causes older adults to be more vulnerable to serious health risks such as joint injuries, bone fractures and traumatic brain injury. The costs associated with the treatment and management of these injuries are a huge financial/social burden on the government, society and family. Knee is one of the key joints that bear most of the body weight, so its proper function is essential for good mobility. Further, Continuous monitoring of the knee joint can potentially provide important quantitative information related to knee health and mobility that can be utilized for health assessment and early diagnoses of mobility-related problems. In this research work, we developed an easy-to-use, low-cost, multi-sensor-based wearable device to monitor and assess the knee joint and proposed an analysis system to characterize and classify an individual’s knee joint features with respect to the baseline characteristics of his/her peer group. The system is composed of a set of different miniaturized sensors (inertial motion, temperature, pressure and galvanic skin response) to obtain linear acceleration, angular velocity, skin temperature, muscle pressure and sweat rate of a knee joint during different daily activities. A database is constructed from 70 healthy adults in the age range from 18 to 86 years using the combination of all signals from our knee joint monitoring system. In order to extract relevant features from the datasets, we employed computationally efficient methods such as complementary filter and wavelet packet decomposition. Minimum redundancy maximum relevance algorithm and principal component analysis were used to select key features and reduce the dimension of the feature vectors. The obtained features were classified using the support vector machine, forming two distinct clusters in the baseline knee joint characteristics corresponding to gender, age, body mass index and knee/leg health condition. Thus, this simple, easy‐to‐use, cost-effective, non-invasive and unobtrusive knee monitoring system can be used for real-time evaluation and early diagnoses of joint disorders, fall detection, mobility monitoring and rehabilitation. / Thesis / Master of Applied Science (MASc)

Bakgrund: Uppmärksamhetsfokus på omgivningen/externt fokus har återkommande visat förbättra motorisk färdighet, inlärning och prestation under flertalet olika motoriska uppgifter i jämförelse med fokus på egna kroppen/internt fokus. Instruktioner som uppmuntrar till internt fokus är mer förekommande vid rehabiliteringen av skador som ruptur av främre korsbandet, däremot har externt fokus visats påverka kinematiska variabler som kan minska risken för återskada. Uppmärksamhetsfokus inverkan på kinematiken under knäböj på vippbräda har dock inte studerats tidigare. Syfte: Syftet var att undersöka om instruktioner som uppmuntrar olika uppmärksamhetsfokus har en inverkan på uförande mätt som rörelseflyt, knästabilitet och balans under ett knäböj på vippbräda samt om det fanns skillnader i utförande mellan personer utan knäskada och personer med främre korsbandsrekonstruktion (ACLr). Metod: Sexton deltagare (11 icke-skadade, 5 ACLr) genomförde sex knäböj på en vippbräda under tre omgångar med instruktioner som uppmuntrade till antingen inget särskilt fokus (neutralt), externt fokus (på vippbrädan) eller internt fokus (på fötterna). Alla knäböj registrerades med ett tredimensionellt kamerasystem. Neutralt fokus utfördes först följt av externt eller internt fokus i randomiserad ordning. Utfallsvariabeln rörelseflyt mättes som avvikelser i knäböjets hastighetskurva, knästabilitet som adduktion/abduktion av underbenet och balans som brädans avvikande lutning i horisontalplan. Resultat: Internt fokus ledde till signifikant mindre knäadduktion (gruppmedian skillnad 1.9°) under flexionsfasen när man slog ihop alla 16 deltagare jämfört med neutralt fokus. Inga andra signifikanta resultat noterades mellan uppmärksamhetsfokus eller mellan grupperna utifrån utfallsvariablerna.   Slutsats: Uppmärksamhetsfokus hade ingen konsekvent inverkan på rörelseflyt, balans och knästabilitet bland våra deltagare. Fler studier med högre deltagarantal vid liknande komplexa uppgifter behövs.

Orientador: Aparecido Augusto de Carvalho / Abstract: In the last few years, several studies have been carried out showing that neuromuscular electrical stimulation (NMES) can produce good therapeutic results in patients with spinal cord injury (SCI). This research introduces a new robust and intelligent control-based methodology for human lower limb rehabilitation via NMES using a continuous-time control technique named robust integral of the sign of the error (RISE). Although in the literature the RISE controller has shown good results without any fine-tuning method, a trial and error approach would quickly lead to muscle fatigue in SCI patients. Therefore, it was shown in this study that the control performance for robustly tracking a reference signal can be improved through the proposed approach by providing an intelligent tuning for each voluntary. Simulation results with a mathematical model and eight identified subjects from the literature are provided, and real experiments are performed with seven healthy and two paraplegic subjects. Besides, this research introduces the application of deep and dynamic neural networks namely the multilayer perceptron, a simple recurrent neural network, and the Long Short-Term memory architecture, to identify the nonlinear and time-varying relationship between the supplied NMES and achieved angular position. Identification results indicate good fitting to data and very low mean square error using few data for training, proving to be very prospective methods for proposing control-oriented ... (Complete abstract click electronic access below) / Resumo: Nos últimos anos, vários estudos foram realizados mostrando que a estimulação elétrica neuromuscular (EENM) pode produzir bons resultados terapêuticos em pacientes com lesão medular (LM). Esta pesquisa introduz uma nova metodologia robusta e inteligente baseada em controle para a reabilitação de membros inferiores humanos via EENM usando uma técnica de controle de tempo contínuo chamada robust integral of the sign of the error (RISE). Embora na literatura o controlador RISE tem demonstrado bons resultados sem qualquer método de ajuste fino, uma abordagem de tentativa e erro poderia levar rapidamente à fadiga muscular em pacientes com LM. Portanto, foi mostrado nesse estudo que o desempenho do controle para rastrear com robustez um sinal de referência pode ser melhorado através da abordagem proposta, fornecendo um ajuste inteligente para cada voluntário. Resultados de simulação com um modelo matemático e oito sujeitos identificados da literatura são fornecidos, e experimentos reais são feitos com sete indivíduos saudáveis ​​e dois paraplégicos. Além disso, esta pesquisa introduz a aplicação de redes neurais profundas e dinâmicas, especificamente o perceptron multicamadas, uma rede neural recorrente simples e a arquitetura Long Short-Term Memory, para identificar a relação não-linear e variante no tempo entre a EENM fornecida e a posição angular alcançada. Os resultados de identificação indicam boa adaptação aos dados e erro quadrático médio muito baixo usando poucos dados para... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Temos aktualumas: Siekiant įvertinti kelio sąnario funkciją po priekinio kryžminio raiščio plyšimo naudojami įvairūs metodai: izokinetinis testavimas dinamometru (Kannus et al., 1992; Risberg et al., 2009), judesio analizė (Risberg et al., 2009), elektromiografija, klinikiniai testai (Irrgang, 2003; Lee et al., 2008) ir klausimynai (Irrgang, 2001; Lee et al., 2008). Ieškodami patikimesnių būdų įvertinti žmogaus nervų- raumenų sistemos valdymo efektyvumą, Kauno technologijos universiteto ir UAB „Katra“ specialistai kartu su Lietuvos kūno kultūros akademija sukūrė naują originalų prietaisą – žmogaus rankų ir kojų judesių dinaminių parametrų analizatorių (DPA–1). Tyrimo objektas: DPA testų patikimumas ir informatyvumas. Tyrimo tikslas: Nustatyti DPA–1 testų patikimumą ir informatyvumą po priekinio kryžminio raiščio rekonstruojamosios operacijos. Tyrimo uždaviniai: 1. Nustatyti DPA–1 testų patikimumą, atliekant standartines ir variabilias užduotis po priekinių kryžminių raiščių rekonstruojamosios operacijos. 2. Nustatyti DPA–1 testų informatyvumą, atliekant standartines ir variabilias užduotis po priekinių kryžminių raiščių rekonstruojamosios operacijos. Tyrimas atliktas Lietuvos kūno kultūros akademijoje „Žmogaus motorikos“ laboratorijoje. Jame dalyvavo 34 tiriamieji, kurie buvo suskirstyti į dvi grupes. Pirmąją grupę sudarė pacientai, patyrę kelio sąnario priekinio kryžminio raiščio rekonstruojamąją operaciją (n=17). Šių tiriamųjų amžiaus vidurkis – 31,3 ± 7,8 metai, ūgis –... [toliau žr. visą tekstą] / Relevancy: Different methods are used to assess capabilities of knee function after ACL injury including isokinetic dynamometry (Kannus et al., 1992, Risberg et al., 2009), motion analysis (Chmielewski et al., 2005, Risberg et al., 2009), electromyography (Chmielewski et al., 2005), clinical testing (Irrgang, 2003, Lee et al., 2008) and questionnaires (Irrgang, 2001, Lee et al., 2008). In order to devise more reliable methods to evaluate the efficiency of human neuromuscular control, the dynamic parameters’ analyzer of human’s hands and legs movements (DPA-1, Patent No. 5251; 2005 08 25) was constructed by Kaunas Technology University and „Katra“ engineers in collaboration with Lithuanian Academy of Physical Education. The object of the study: the reliability and validity of DPA-1 testing procedures. The aim of the study is to establish the reliability and validity of DPA-1 testing procedures after anterior cruciate ligaments reconstructive surgery. The goals of the study are the following: 1. To establish the reliability of DPA-1 testing procedures while performing standard and variable tasks after anterior cruciate ligaments reconstructive surgery. 2. To establish the validity of DPA-1 testing procedures while performing standard and variable tasks after anterior cruciate ligaments reconstructive surgery. The recearch was performed in the Laboratory of Human Motorics at the Lithuanian Academy of Physical Education. 34 participants, who were divided into two groups... [to full text]

The knee joint plays an essential role in the human musculoskeletal system. It has evolved to withstand extreme loading conditions, while providing almost frictionless joint movement. However, its performance may be disrupted by disease, anatomical deformities, soft tissue imbalance or injury. Knee disorders are often puzzling, and accurate diagnosis may be challenging. Current evaluation approach is usually limited to a detailed interview with the patient, careful physical examination and radiographic imaging. The X-ray screening may reveal bone degeneration, but does not carry sufficient information of the soft tissue conditions. More advanced imaging tools such as MRI or CT are available, but expensive, time consuming and can be used only under static conditions. Moreover, due to limited resolution the radiographic techniques cannot reveal early stage arthritis. The arthroscopy is often the only reliable option, however due to its semi-invasive nature, it cannot be considered as a practical diagnostic tool. Therefore, the motivation for this work was to combine three scientific methods to provide a comprehensive, non-invasive evaluation tool bringing insight into the in vivo, dynamic conditions of the knee joint and articular cartilage degeneration. Electromyography and inverse dynamics were employed to independently determine the forces present in several muscles spanning the knee joint. Though both methods have certain limitations, the current work demonstrates how the use of these two methods concurrently enhances the biomechanical analysis of the knee joint conditions, especially the performance of the extensor mechanism. The kinetic analysis was performed for 12 TKA, 4 healthy individuals in advanced age and 4 young subjects. Several differences in the knee biomechanics were found between the three groups, identifying age-related and post-operative decrease in the extensor mechanism efficiency, explaining the increased effort of performing everyday activities experienced by the elderly and TKA subjects. The concept of using accelerometers to assess the cartilage degeneration has been proven based on a group of 23 subjects with non-symptomatic knees and 52 patients suffering from knee arthritis. Very high success (96.2%) of pattern classification obtained in this work clearly demonstrates that vibroarthrography is a promising, non-invasive and low-cost technique offering screening capabilities.

La sécurité du piéton est un problème de santé publique, qui doit être traité tant par les acteurs de la recherche que par l'industrie automobile pour apporter des solutions technologiques innovantes. Dans les accidents impliquant des piétons, le premier contact est généralement localisé sur les membres inférieurs exhibant de fréquentes et nombreuses lésions pouvant être très sévères. Compte tenu des caractéristiques biomécaniques du membre inférieur, comment améliorer les critères de blessures existants pour contribuer au développement d'une voiture moins agressive pour les piétons ? La présente étude vise donc à promouvoir des améliorations significatives de critères de blessure des membres inférieurs pour la sécurité des piétons combinant des essais expérimentaux et des simulations numériques. Un modèle par éléments finis des membres inférieurs (modèle LLMS) a été utilisé et amélioré pour étudier les réponses mécaniques des membres inférieurs dans des conditions de chargement realists. Une attention particulière a été accordée sur la capacité du modèle à prédire séparément les blessures des os longs et celles de l'articulation du genou pour développer deux critères de blessures distincts. Pour le tibia, la nature de sa structure et les conditions de chargement qui lui sont appliquées nous ont conduit à proposer une courbe quadratique de moment en flexion qui tient compte de différents points d'impact. Pour le genou, le critère de blessure a été établi à partir d'une fonction combinant cisaillement latéral et flexion latérale. Ce critère permet de hiérarchiser la nature et la sévérité des lésions en fonction du mécanisme de blessure prépondérant. / Pedestrian safety is a worldwide concern, which needs to be investigated by both vehicle manufacturers and researchers to approach innovative solutions. In car-Pedestrian accidents, lower limbs have been demonstrated to be the most frequently injured body region of the pedestrian. Given the biomechanical features of lower limbs, how the existing injury criteria could be improved to aid the development of a pedestrian friendly car? The current study aims to promote significant improvements in the injury criteria of lower limbs for pedestrian safety combining experimental tests and numerical simulations. A finite element lower limb model (LLMS model) was used and improved to investigate the mechanical responses of lower limbs in the loading conditions reflecting the car-Pedestrian impact. A particular attention was paid on the model ability of predicting separately the injuries of long bones and knee joints to develop the corresponding injury criteria. With regard to the tibia structure and its loading condition in pedestrian accidents, we proposed a quadratic curve of bending moments to tibia locations as its injury tolerance. Given dominant injury mechanisms of the ligaments, the knee injury criterion was established as a function of combined joint kinematics including lateral bending and lateral shearing. Moreover, these criteria are relevant with the previous and current experimental test results. Finally, the efficiency of the proposed criteria was evaluated by a parametric study of the realistic car-Pedestrian impact conditions.

The present study is divided into theoretical and practical part. The theoretical part deals with anatomy of thehip andknee joint, in the next part there is definition of endoprosthesis as well as historical development of endoprosthesis. Subsequently, different types of endoprosthesis, surgery equipment and possible complications after surgery are described. It is followed by nursing care and rehabilitation including spa treatment. The theoretic part is concluded with revision of the joint. The practical part of the master thesis has been elaborated from the qualitative survey. The survey was conducted with the respondents who underwent endoprosthesisof the knee or hip joint and with the nurses working at regular orthopaedic department or orthopaedic intensive care unit (ICU). The interviews were afterwards transcribed and elaborated by means of the technique of open coding with the method "pencil and paper". 16 categories and 48 subcategories emerged from the data processed in this manner.

Abstract Primary hallmark of osteoarthritis (OA) is the progressive degeneration of articular cartilage. An accurate estimation of cartilage mechanics is important when analyzing the subject-specific function of the knee joint and risks for the onset and development of OA due to cartilage damage. Finite element (FE) modeling can help to estimate peak joint stresses and strains and explain how they could lead to OA. FE models of the knee joint during simplified gait were developed to define the level of material complexity required for 3D FE modeling of the knee joint in estimation of reliable tissue stresses and strains within articular cartilage of the knee joint; and to investigate the predictive value of FE modeling of the knee joint on the development and progression of radiographic OA within obese and normal weight subjects. It was found that maximum principal stresses and strains within articular cartilage in the knee joint during walking are highly sensitive to the material parameters of cartilage. It was not possible to match simultaneously stresses, strains and contact pressures between simplified (non-fibrillar) and advanced (fibrillar) models. Though, it was possible to find parameters for transversely isotropic models that enable the estimation of stresses and strains throughout the depth of cartilage similarly to more advanced fibril reinforced models. Locations of peak cumulative stresses in obese subjects at the baseline without radiographic OA showed a good agreement with the locations of cartilage loss and magnetic resonance imaging (MRI) based scoring in four year follow-up when they had developed OA. Simulated weight loss in obese subjects significantly reduced the highest cumulative stresses in cartilage to the level of normal weight subjects. The cartilage degeneration algorithm was able to predict subject-specific progression of OA similarly with MRI follow-up data and separate subjects with radiographic OA from healthy subjects. The computational FE models developed in this thesis represent useful tools to identify possible risk locations within the knee joint and how they relate to OA onset and progression. The presented methods have clinical potential in the diagnostics of knee joint OA in a subject-specific manner and in simulating the effect of interventions on the progression of OA thus helping with an effective treatment planning. / Tiivistelmä Nivelrikon tunnusomaisin piirre on nivelrustokudoksen rappeutuminen ja kuluminen. Nivelruston tehtävänä on tasata niveliin kohdistuvaa kuormitusta. Rustokudoksen mekaanisten ominaisuuksien määrittäminen on tärkeässä roolissa, kun halutaan arvioida tarkemmin polvinivelen toimintakykyä sekä rustokudoksen rappeutumista. Magneettikuvantamisen pohjalta tehtävä polvinivelen biomekaaninen tietokonemallinnus mahdollistaa rustokudoksen jännitys- ja puristusjakauman arvioinnin simuloidun kuormituksen aikana, mikä edelleen voi antaa vastauksia siihen, kehittyykö niveleen tulevaisuudessa nivelrikko, tai miten tietyn nivelrikkopotilaan sairaus etenee. Tämän tutkimuksen päätavoitteena oli kehittää kolmiulotteisia polvinivelen biomekaanisia tietokonemalleja, joiden perusteella simuloitiin normaalia kävelyä. Polvinivelen kolmiulotteinen geometria luotiin terveiden koehenkilöiden sekä nivelrikkopotilaiden magneettikuvista. Malleilla selvitettiin aluksi, miten monimutkaisena materiaalina nivelrusto tulee mallintaa, jotta mallin ennustama jännitys- ja puristusjakauma on silti realistinen. Tämän jälkeen tutkittiin, miten hyvin tietokonemallinnus ennustaa polvinivelrikon kehittymistä ja etenemistä sekä nivelruston rappeutumista ylipainoisilla potilailla. Tutkimuksessa havaittiin, että tietokonemallin ennustamat jännitys- ja puristusjakaumat nivelrustossa kävelyn aikana riippuvat merkittävästi nivelrustolle valitusta materiaalimallista ja sen parametreista. Tietokonemallien ennustamat nivelruston jännityskeskittymien sekä ruston rappeutumisen sijainnit vastasivat erittäin hyvin nivelrustokudoksen todellisen kulumisen sijainteja magneettikuvasta arvioituna neljän vuoden seuranta-ajan jälkeen. Tietokonemalleilla oli myös mahdollista simuloida painon pudotuksen vaikutusta, jolloin nivelrustokudoksen jännitys- ja puristusjakaumat palautuivat normaalien koehenkilöiden tasolle. Tässä tutkimuksessa kehitetyt polvinivelen tietokonemallit tarjoavat tutkijoille uuden työkalun paikallistaa sellaiset kohdat nivelpinnalta, joissa kuormituksen aiheuttama mekaaninen jännitys on suurta; nämä kohdat ovat kaikista riskialtteimpia nivelrikon kehittymiselle. Kehitettyjä malleja voidaan perustutkimuksen lisäksi jatkokehittää edelleen kohti kliinistä sovellusta, jolloin niitä voitaisiin hyödyntää esimerkiksi simuloitaessa erilaisten hoitojen vaikutusta kuormitusjakaumiin ja rustokudoksen rappeutumiseen.