Comment rééquilibrer les ligaments du genou sans ré-opérer un patient ?

Un nouveau volet de Demain Chez Vous a été publié! Après le premier épisode, c’est au tour de mon projet de thèse 🙂

L’arthrose conduit à la pose de près de 70 000 prothèses du genou par an en France. Au fil du temps, la prothèse subit l’évolution des modes de vie du patient ce qui peut conduire au descellement de la prothèse ou à déséquilibrage des ligaments. Il est alors nécessaire de procéder à une chirurgie dite de reprise. Pour pallier ce problème une nouvelle génération d’implants orthopédiques instrumentés est en cours de développement à Télécom Bretagne. Le médecin pourra corriger la tension des ligaments en actionnant le système placé dans la prothèse.
Ce dispositif innovant et prometteur est développé à Télécom Bretagne au Latim, sous la responsabilité de Chafiaa Hamitouche.

Squat movements: some hints

source: this website

The squat movement can be described as a compound exercise which involves multiple groups of muscles. It is usually performed by recreational and professional athletes to strengthen hip, knee and ankle muscles. The squat exercise consists of two main phases, lowering and standing.

The lowering phase

The body starts from a standing position and, replicating the motion performed while sitting on a chair, it is lowered until the squat configuration is achieved. All the lower limb joints are involved, with several groups of muscles that contract as they lengthen. This results in eccentric contractions.squatL

  • Hip: flexion movement. The hip extensors (gluteus maximus, semimembranosus, semitendinosis and biceps femoris) mainly control the speed of the body, whose lowering is naturally supported by gravity.
  • Knee: flexion movement. The knee extensors (rectus femoris, vastus medialis, vastus intermedius and vastus lateralis) mainly allow to tune the knee bending speed.
  • Ankle: dorsiflexion movement. The plantarflexor muscles (gastrocnemius and soleus) mainly counteract the pull of gravity and provide a stable support on the ground.
The standing phase

squatSThe body leaves the squat configuration and returns to an upright position. The speed of this movement is continuously controlled, as well as the stable support provided by the feet. Once again, this is ensured by the combined action of all the lower limb joints. The same groups of muscles as for the lowering phase now shorten as they contract. This produces concentric contractions.

  • Hip: extension movement. The hip extensors mainly bring the trunk back to an upright position.
  • Knee: extension movement. The knee extensors help contracting and smoothly straightening the knee joints.
  • Ankle: plantarflexion movement. The plantarflexor muscles push down against the ground and are responsible for the overall stability of the body.


the chairless chair by Noonee

source: L. Seward’s post on this website

Coming out of NCCR Robotics lab, the Bio-Inspired Robotics laboratory at University of Cambridge (previously at ETH Zurich, Switzerland), Noonee® is a revolutionary start-up business aiming to solve healthcare problems within the manufacturing industry. The idea is to provide an exoskeleton that supports the weight of the user only when they feel tired , rather than continuously taking on this weight – meaning that the wearer is using their muscles and actively, rather than passively, sitting.

P8iHDpcWithin the manufacturing industry, keeping employees healthy has been a major concern and challenge for many companies around the world for a long time. Jobs often involve spending long periods of time bending and crouching and as a result can leave staff with substantial back and knee problems. Of 215 million industry sector workers in the EU, a staggering 85 million are reported to suffer from muscle related disorders. Market solutions that are currently available may also pose problems as they limit short term tiredness by taking all the weight of the user, which can lead to muscle weakening. What is needed is a product that can support staff working on production lines while keeping them healthy. The “chair” is not a chair as we know it, but more of an exoskeleton for the legs with a belt to attach it to the hips and straps that wrap around the thighs. The slim structure has joints that allow the wearer to move freely, but when the wearer is in a position they wish to stay in for a long time (e.g. crouching under a car on a production line), this position can be fixed, meaning that the wearer does not need to use the same muscle groups for long periods of time to hold the position. The advantage of such a structure is that it can be worn anywhere and can also be used when standing and walking. This reduces the space required as compared to a traditional chair and reduces the hassle when compared to other solutions, such as chairs that are strapped to the user.

imageThe Chairless Chair® is currently still in prototype and the current version requires the user to fix a position by crouching down into the required position and pushing a button. It is hoped that future iterations of the Chairless Chair® will be actuated to allow the system to become intelligent and understand the intention of the user, allowing it to be fixed into position without any additional input from the wearer.

all’IIT si stampano cartilagini!

da quest’articolo de La Repubblica dell’11/10/15

L’intuizione del genovese Luca Coluccino: togliere la “memoria” al tessuto e riprodurlo

L’idea gli è venuta a Pittsburgh — la città della Pennsylvania famosa per Flashdance e le antiche industrie dell’acciaio — ma continuerà a svilupparla sulla collina di Morego, a Genova, nell’Istituto Italiano di Tecnologia. Luca Coluccino ha 28 anni, una laurea in ingegneria biomedica e una passione per le articolazioni delle ginocchia. Lo si capisce dalla tesi di laurea e dal suo dottorato di ricerca al’IIT, dove dal 2013 studia come ricostruire e riparare le cartilagini.

084139429-51f017df-9dea-4c3a-95e2-cc1e89146d41Lo scorso anno, durante un periodo all’Università di Pittsburgh, Luca ha azzardato: “Ma perché invece di fare protesi sintetiche non proviamo a creare una cartilagine vera? Una cartilagine senza parti artificiali. Biologica, umana. E poi usiamo questo tessuto senza forma come “inchiostro” per una stampante in 3D“. Era un’idea un po’ folle: creare la cartilagine è l’ambizione dei gruppi di ricerca più avanzati del mondo, dalla Corea del Sud agli Stati Uniti. Ci provano da anni, senza successo. Ma Luca e il team con cui lavora — il gruppo Smart Materials del Dipartimento di Nanofisica dell’IIT — ci sono riusciti. E a metà settembre hanno spiegato come fare al TERMIS di Boston, la conferenza mondiale di riferimento per la medicina rigenerativa.

Luca arriva all’IIT con un maggiolone anni ’70, la giacca stilosa e una barbetta bionda accennata. A parlar di cartilagini gli si illuminano gli occhi. “Sono affascinanti perché non si ricreano come le ossa — spiega — Se un adulto ha una lesione grave a una cartilagine bisogna sostituirla con protesi metalliche o plastiche. Ma sono parti estranee al corpo umano: causano problemi di rigetto e non durano all’infinito“. Tra qualche anno potrebbe non essere più così, perché il team dell’IIT in collaborazione con l’Università di Pittsburgh (dove Coluccino era sotto la guida di un altro genovese, il ricercatore Riccardo Gottardi) ha trovato la “ricetta” per ricostruire cartilagini, tendini e menischi. Ad ascoltare Luca Coluccino sembra semplice: si tratta chimicamente una cartilagine, per esempio, sino a farla diventare un liquido che ha perso tutte le informazioni che nel corpo di un’altra persona potrebbero dare reazione immunitaria. “Solo una cosa le deve rimanere: la ‘memoria’ di essere una cartilagine“, avverte Coluccino.

Prosthetic Knee Systems Overview

source: Bill Dupes’s original post published on this website


Prosthetic knees have evolved greatly over time, from the simple pendulum of the 1600s to those regulated by rubber knees01bands and springs or pneumatic or hydraulic components. Now, some knee units have advanced motion control modulated through microprocessors. For the transfemoral (above-knee, including hip and knee disarticulation) amputee, successful function depends on selecting the correct knee to fit the person’s age, health, activity level and lifestyle. The latest or advanced knee is not necessarily the best choice for everyone. For some amputees, safety and stability are more important than functional performance. Active amputees, on the other hand, prefer a knee that will give them a higher level of function even if it requires greater control.

Given the wide variety of choices and consumer needs, prosthetists and rehabilitation specialists can help amputees choose the best prosthetic knees for their individual requirements. They can also teach amputees how to use their new knees properly, which is critical for avoiding discomfort, stumbling and falling. A key way to evaluate an individual’s prosthetic needs is to observe his or her walking cycle, which can be divided into two parts: the “stance phase” (when the leg is on the ground supporting the body) and the “swing phase” (when the leg is off the ground, also referred to as “extension”). The happy medium between these two extremes (stance, or stability, versus ease of swing, or flexion) is different for each individual.

Although over 100 individual knee mechanisms are commercially available, they can be divided into two major classifications: mechanical and computerized. Mechanical knees can be further separated into two groups: single-axis knees and polycentric, or multiaxis, knees. All knee units, regardless of their level of complexity, require additional mechanisms for stability (manual or weight-activated locking systems) and additional mechanisms for control of motion (constant or variable friction and “fluid” pneumatic or hydraulic control).

Single-Axis Vs. Polycentric Knees

The single-axis knee, essentially a simple hinge, is generally considered the “workhorse” of the basic knee classes due to its knees02relative simplicity, which makes it the most economical, most durable, and lightest option available. Single-axis knees do have limitations, however. By virtue of their simplicity, amputees must use their own muscle power to keep them stable when standing. To compensate for this, the single-axis knee often incorporates a constant friction control and a manual lock. The friction keeps the leg from swinging forward too quickly as it swings through to the next step.

knees03Polycentric knees, also referred to as “fourbar” knees, are more complex in design and have multiple axes of rotation. Their versatility is the primary reason for their popularity. They can be set up to be very stable during early stance phase, yet easy to bend to initiate the swing phase or to sit down. Another popular feature of the knee’s design is that the leg’s overall length shortens when a step is initiated, reducing the risk of stumbling. Polycentric knees are suitable for a wide range of amputees. Various versions are ideal for amputees who can’t walk securely with other knees, have knee disarticulation or bilateral leg amputations, or have long residual limbs. A standard polycentric knee has a simple mechanical swing control that provides an optimal single walking speed; however, many polycentric knees incorporate fluid (pneumatic or hydraulic) swing control to permit variable walking speeds. The most common limitation of the polycentric design is that the range of motion about the knee may be restricted to some degree, though usually not enough to pose a significant problem. Polycentric knees are also heavier and contain parts that may need to be serviced or replaced more often than those of other types of prosthetic knees.

Microprocessor Knees

Microprocessor knees are a relatively new development in prosthetic technology. Onboard sensors detect movement and timing and then knees04adjust a fluid /air control cylinder accordingly. These microprocessor-controlled knees lower the amount of effort amputees must use to control their timing, resulting in a more natural gait. In spite of all of the amazing inventions and constant tweaks and improvements, the perfect prosthetic knee has yet to be invented; otherwise, there wouldn’t be over 100 different designs on the market. As advanced as the technology seems today compared to the earliest designs of the 1600s, one can only imagine the developments that will eventually result as researchers further explore the potential of mechanical, hydraulic, computerized and “bionic,” or neuroprosthetic, technology.

– by the way, my CV is finally up-to-date! –

assistive devices comparison

what-are-crutch-alternativesTwo weeks ago I stumbled upon this interesting website, which provides useful information about different assistive devices. I tried to make a list of Pros & Cons of crutches, walkers and exoskeletons (as for the latter category, in very general terms) in order to compare them from a more global point of view. The result is the table below here, that you can zoom by a simple click.

Would you help me complete it? For sure it contains mistakes and inaccuracies, and further details should be added 🙂


La prothèse du genou autonome et adaptative d’Andrea Collo

source: le blog recherche de l’Institut Mines-Télécom

Qui sera le grand gagnant du prix de thèse Futur&Ruptures ? Réponse le 7 avril prochain, lors de la cérémonie de remise des Prix de la Fondation Télécom. Auteurs de thèses distinguées pour leur excellence, les trois lauréats recevront chacun un prix, pour un montant total de 9 500 €. En attendant de connaître le classement final, nous vous présentons dans une série de trois billets leurs travaux, menés au sein des laboratoires des écoles de l’Institut Mines-Télécom. 


Andrea-ColloAndrea Collo a été récompensé pour ses travaux, menés à Télécom Bretagne, sur le développement d’une prothèse du genou autonome et adaptative, capable de compenser les déséquilibres ligamentaires qui peuvent advenir après l’opération.

L’arthroplastie totale de genou (ATG) est une opération chirurgicale qui consiste à remplacer entièrement l’articulation du genou par une prothèse suite à plusieurs maladies (arthrose, ostéoporose, usure et défauts des tissus mous de l’articulation, déchirures des ligaments et des cartilages). Pour éliminer la douleur et rétablir la mobilité du genou, la prothèse doit être positionnée de manière à ATGgarantir l’équilibre ligamentaire au niveau des deux ligaments collatéraux du genou, les seuls qui ne sont pas enlevés. Or, dans environ 10% des cas, après l’opération, il arrive que les composants prothétiques s’écartent légèrement de leur position de départ, et qu’un des ligaments se relâche. Cela entraîne des douleurs sévères et une mobilité réduite chez le porteur de prothèse, ainsi que l’usure prématurée de la prothèse. À l’heure actuelle, la seule solution pour rétablir des conditions d’équilibre optimales est la chirurgie de reprise, une intervention extrêmement coûteuse (entre 30 et 50 k€) et contraignante à la fois pour le patient et le chirurgien. À l’heure actuelle, environ 19 ATG de reprise sont réalisées chaque jour en France (95 aux USA).

Correction-déséquilibre-ligamentaireAndrea Collo a donc conçu un mécanisme miniaturisé, robuste et biocompatible, qui permet de retendre un ligament relâché en postopératoire sans avoir recours à la chirurgie. Le système est embarqué dans le composant tibial de la prothèse : une vis sans fin permet de déplacer une cale, qui vient soulever le plateau tibial du côté du ligament relâché, ce qui a pour effet de le retendre. Le système d’actionnement est alimenté et contrôlé à distance, par induction magnétique et via un système de télémétrie miniaturisé. Cette technique permet de compenser le déséquilibre ligamentaire et de modifier l’alignement tibiofémoral jusqu’à 3 degrés.

act2Pour ce projet, il s’est appuyé sur la prothèse intelligente précédemment développée par Shaban Almouahed : grâce à quatre capteurs de force piézoélectriques intégrés dans la partie tibiale de la prothèse, elle est capable de détecter le relâchement d’un ligament et d’envoyer les données récoltées au chirurgien par radiofréquence. Grâce à ces données, celui-ci peut estimer au millimètre près le nombre de tours de vis nécessaires pour retendre le ligament. Il lui suffit ensuite d’actionner le mécanisme développé par Andrea Collo. Le chercheur a mis au point un prototype fonctionnel, testé avec succès sur un simulateur de genou. Il vient d’obtenir un financement sur 24 mois de l’Agence nationale de la recherche (ANR projet Emerge), qui va lui permettre d’améliorer encore son prototype, notamment la miniaturisation du moteur qui actionne le mécanisme, et peut-être d’entrer en phase de validation clinique.