Year: 2016
Type: dissertation
Abstract: RESUME
L'arthrose (OA), la maladie chronique la plus repandue chez les personnes âgees, est l'une des
principales causes d'invalidite dans notre societe avec une incidence qui s’accroit dans le monde
entier. L'arthrose resulte de la deterioration ou de la perte du cartilage articulaire qui agit comme
un coussin de protection entre les os. Comme l'incidence de l'arthrose est en progression
constante, il y a un besoin urgent de techniques d'evaluation non invasives pouvant etre efficaces
avant le debut de la degradation irreversible du cartilage. Les techniques actuelles d’evaluation
comprennent l'evaluation clinique, l'arthroscopie et les modalites d'imagerie telles que les rayons
X, l’imagerie par resonance magnetique (IRM) et la tomographie par ordinateur (CT). Bien que
ces techniques soient couramment utilisees pour le diagnostic de l'arthrose en evaluant la
formation d'osteophytes, le pincement articulaire et les lesions osseuses, aucune d'elles ne peut
detecter les changements precoces dus a l'arthrose du genou.
La necessite d'une evaluation precoce et precise de l'integrite du cartilage a incite de nombreux
chercheurs a explorer une variete de techniques. Par exemple, la transduction electromecanique
du cartilage, connu sous le nom de « potentiels d'ecoulement », est un indice sensible de
l'integrite du cartilage articulaire qui a ete valide par de nombreuses experiences in vitro. Le
mecanisme sous-jacent est associe a la separation des charges negatives fixes et des contre-ions
mobiles dans la phase liquide du cartilage durant sa compression. Un instrument arthroscopique
(Arthro-BST) a ainsi ete concu pour mesurer les potentiels d’ecoulement directement sur la
surface du cartilage articulaire comprime pour en evaluer la qualite lors d’une intervention
chirurgicale. Une approche similaire, mais non invasive, a ensuite ete developpee pour mesurer
les potentiels apparaissant a la surface du genou pendant son chargement et refletant les
potentiels d'ecoulement sous-jacents. Cette technique est appelee electroarthrographie (EAG). La
mise en charge du cartilage consiste simplement, pour un sujet debout, a deplacer son poids sur la
jambe instrumentee. Meme si les premieres mesures de l’EAG etaient reproductibles, une
certaine variabilite des signaux EAG enregistres chez le meme sujet a ete observee, ce qui peut
entraver son application comme outil de diagnostic de l'arthrose. Le but de notre etude etait donc
d'etudier la nature de la variabilite des signaux EAG afin de contribuer a l'elaboration de
meilleures techniques de mesure.----------ABSTRACT
Osteoarthritis (OA), the most prevalent chronic progressive disease of the elderly, is one of the
leading causes of disability in our society with increasing incidence throughout the world. OA
results from the deterioration or loss of articular cartilage acting as protective cushion between
the bones. As the incidence of OA is on a continuous increase, there is an urgent need for noninvasive
assessment techniques that can be effective before the onset of irreversible degradation.
Current technologies to assess the joint function include clinical evaluation, arthroscopy and
imaging techniques such as X-ray, magnetic resonance imaging (MRI) and computed
tomography (CT). Although these techniques are widely used to assist the diagnosis of OA by
evaluating osteophyte formation, joint space narrowing and bone damage, none of them can show
osteoarthritic changes of the knee until the later OA stages.
The need for an early and accurate evaluation of the integrity of cartilage has prompted many
investigators to explore a variety of techniques. For example, the electromechanical transduction
of cartilage, known as streaming potentials, is a sensitive index of the integrity of articular
cartilage that has been validated by many in-vitro experiments. The underlying mechanism is
associated with the separation of fixed negative charges and mobile counterions in the liquid
phase of the cartilage under compression. A hand-held arthroscopic instrument (Arthro-BST) has
thus been designed to measure the electrical potentials directly over compressed articular
cartilage to assess its quality. A non-invasive approach, electroarthrography (EAG) was later
developed to measure the electrical potentials appearing on the surface of knee during loading
and reflecting the underlying streaming potentials. Mechanical loading simply consisted of
shifting the body weight of the erect subject to the instrumented leg. Even though the first EAG
measurements were repeatable, variability in the EAG signals recorded in the same subject was
observed, which can hamper its application as a diagnostic tool for OA. The aim of our study was
thus to investigate the nature of the variability of the EAG signals and to contribute to the
development of better measurement techniques.
The first objective of this study was to investigate how the contraction of certain leg muscles in
supine subjects affects the contact force of the knee joint and, in turn, the EAG values. Voluntary
isometric muscle contractions were repeatedly conducted to selectively activate four leg muscle
groups while six subjects were lying on their back. Two EAG signals were recorded on both
Author: Lin Zhu
Language: English
Subfield: Rheumatology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2548679757