Breakthrough implant brings dexterity and sense of touch to prosthetic hand

Breakthrough implant brings dexterity and sense of touch to prosthetic hand

There have been significant technological developments in prosthetics in recent years. However, artificial replacements provide limited value in performing everyday tasks where their sensory feedback offers poor functionality. Thanks to the EU-funded DeTOP project, scientists have developed a new implant system enabling the use of a clinically viable, dexterous and sentient prosthetic hand in real life.

As summarised in a news item on the project website after trailblazing surgery a female Swedish patient became the first recipient of titanium implants “in the two forearm bones (radius and ulnar) from which electrodes to nerves and muscle were extended to extract signals to control a and to provide tactile sensations.”

The same item emphasises that traditional “prosthetic hands rely on electrodes placed over the skin to extract control signals from the underlying stump muscles. These superficial electrodes deliver limited and unreliable signals that only allow control of a couple of gross movements (opening and closing the hand).” It also notes that current artificial hands “do not provide tactile or kinesthetic sensation, so the user can only rely on vision while using the prosthesis.” This limits the ability of the user to understand the strength of his or her grip. “Richer and more reliable information can be obtained by implanting electrodes in all remaining muscle in the stump instead.” In the Swedish patient, a total of 16 electrodes were connected to nerves that would have led to the missing hand.

When electrodes are implanted using this technique, “researchers can electrically stimulate these nerves in a similar manner as information conveyed by the biological hand.” Thus, the patient can feel “sensations originating in the new prosthetic hand” with the help of “sensors that drive the stimulation of the nerve to deliver such sensations.”

From laboratory to everyday life

Project partner Integrum AB and Chalmers University of Technology have previously shown that control of a similar prosthesis in daily life was possible in above-elbow amputees as demonstrated in a video. The DeTOP news item points to the challenges involved with the process: “This was not possible in below-elbow amputees where there are two smaller bones rather than a single larger one as in the upper arm. This posed several challenges on the development of the implant system. On the other hand it also presents an opportunity to achieve a more dexterous control of an artificial replacement. This is because many more muscles are available to extract neural commands in below-elbow amputations.”

According to the news item, the patient is currently undergoing a rehabilitation programme to strengthen her forearm bones. She’s also relearning how to control her missing hand, employing prior to fully using the actual prosthetic hand. Two more patients in Italy and Sweden are lined up for such implant surgery.

The ongoing DeTOP (Dexterous Transradial Osseointegrated Prosthesis with neural control and sensory feedback) project “targets people with reduced or absent sensorimotor capabilities due to an amputation” as stated on CORDIS. It adds: “Core of the system is an osseointegrated human-machine gateway (OHMG) able to create bidirectional links between a human and a robotic prosthesis.”

Source of the Article: medicalexpress.com

The first dexterous and sentient hand prosthesis has been successfully implanted

Source: Chalmers University of Technology

Summary:A Swedish patient with hand amputation has become the first recipient of an osseo-neuromuscular implant to control a dexterous hand prosthesis. In a pioneering surgery, titanium implants were placed in the two forearm bones (radius and ulnar), from which electrodes to nerves and muscle were extended to extract signals to control a robotic hand and to provide tactile sensations. This makes it the first clinically viable, dexterous and sentient prosthetic hand usable in real life.

A female Swedish patient with hand amputation has become the first recipient of an osseo-neuromuscular implant to control a dexterous hand prosthesis. In a pioneering surgery, titanium implants were placed in the two forearm bones (radius and ulnar), from which electrodes to nerves and muscle were extended to extract signals to control a robotic hand and to provide tactile sensations. This makes it the first clinically viable, dexterous and sentient prosthetic hand usable in real life. The breakthrough is part of the European project DeTOP.

The new implant technology was developed in Sweden by a team lead by Dr. Max Ortiz Catalan at Integrum AB — the company behind the first bone-anchored limb prosthesis using osseointegration — and Chalmers University of Technology. This first-of-its-kind surgery, led by Prof. Rickard Brånemark and Dr. Paolo Sassu, took place at Sahlgrenska University Hospital as part of a larger project funded by the European Commission under Horizon 2020 called DeTOP (GA #687905).

The DeTOP project is coordinated by Prof. Christian Cipriani at the Scuola Superiore Sant’Anna, and also includes Prensilia, the University of Gothenburg, Lund University, University of Essex, the Swiss Center for Electronics and Microtechnology, INAIL Prosthetic Center, Università Campus Bio-Medico di Roma, and the Instituto Ortopedico Rizzoli.

Conventional prosthetic hands rely on electrodes placed over the skin to extract control signals from the underlying stump muscles. These superficial electrodes deliver limited and unreliable signals that only allow control of a couple of gross movements (opening and closing the hand). Richer and more reliable information can be obtained by implanting electrodes in all remaining muscle in the stump instead. Sixteen electrodes were implanted in this first patient in order to achieve more dexterous control of a novel prosthetic hand developed in Italy by the Scuola Superiore Sant’Anna and Prensilia.

Current prosthetic hands have also limited sensory feedback. They do not provide tactile or kinesthetic sensation, so the user can only rely on vision while using the prosthesis. Users cannot tell how strongly an object is grasped, or even when contact has been made. By implanting electrodes in the nerves that used to be connected to the lost biological sensors of the hand, researchers can electrically stimulate these nerves in a similar manner as information conveyed by the biological hand. This results in the patient perceiving sensations originating in the new prosthetic hand, as it is equipped with sensors that drive the stimulation of the nerve to deliver such sensations.

One of the most important aspects of this work is that this is the first technology usable in daily life. This means it is not limited to a research laboratory. The Swedish group — Integrum AB and Chalmers University of Technology — have previously demonstrated that control of a sentient prosthesis in daily life was possible in above-elbow amputees using similar technology. This was not possible in below-elbow amputees where there are two smaller bones rather than a single larger one as in the upper arm. This posed several challenges on the development of the implant system. On the other hand, it also presents an opportunity to achieve a more dexterous control of an artificial replacement. This is because many more muscles are available to extract neural commands in below-elbow amputations.

Bones weaken if they are not used (loaded), as commonly happen after amputation. The patient is following a rehabilitation program to regain the strength in her forearm bones to be able to fully load the prosthetic hand. In parallel, she is also relearning how to control her missing hand using virtual reality, and in few weeks, she will be using a prosthetic hand with increasing function and sensations in her daily life. Two more patients will be implanted with this new generation of prosthetic hands in the upcoming months, in Italy and Sweden.

“Several advanced prosthetic technologies have been reported in the last decade, but unfortunately they have remained as research concepts used only for short periods of time in controlled environments” says Dr. Ortiz Catalan, Assoc. Prof. at Chalmers University of the Technology and head of the Biomechatronics and Neurorehabilitation Lab, who has led this development since its beginning 10 years ago, initially in above-elbow amputations. “The breakthrough of our technology consists on enabling patients to use implanted neuromuscular interfaces to control their prosthesis while perceiving sensations where it matters for them, in their daily life.”

Video: https://www.youtube.com/watch?v=EES8U5LwaUs&feature=youtu.be

Source of the article: Sciencedaily.com

A prosthetic that restores the sense of where your hand is

Source: Ecole Polytechnique Fédérale de Lausanne

Summary: Researchers have developed a next-generation bionic hand that allows amputees to regain their proprioception. The results of the study are the culmination of ten years of robotics research.

The next-generation bionic hand, developed by researchers from EPFL, the Sant’Anna School of Advanced Studies in Pisa and the A. Gemelli University Polyclinic in Rome, enables amputees to regain a very subtle, close-to-natural sense of touch. The scientists managed to reproduce the feeling of proprioception, which is our brain’s capacity to instantly and accurately sense the position of our limbs during and after movement — even in the dark or with our eyes closed.

The new device allows patients to reach out for an object on a table and to ascertain an item’s consistency, shape, position and size without having to look at it. The prosthesis has been successfully tested on several patients and works by stimulating the nerves in the amputee’s stump. The nerves can then provide sensory feedback to the patients in real time — almost like they do in a natural hand.

The findings have been published in the journal Science Robotics. They are the result of ten years of scientific research coordinated by Silvestro Micera, a professor of bioengineering at EPFL and the Sant’Anna School of Advanced Studies, and Paolo Maria Rossini, director of neuroscience at the A. Gemelli University Polyclinic in Rome.

Sensory feedback

Current myoelectric prostheses allow amputees to regain voluntary motor control of their artificial limb by exploiting residual muscle function in the forearm. However, the lack of any sensory feedback means that patients have to rely heavily on visual cues. This can prevent them from feeling that their artificial limb is part of their body and make it more unnatural to use.

Recently, a number of research groups have managed to provide tactile feedback in amputees, leading to improved function and prosthesis embodiment. But this latest study has taken things one step further.

“Our study shows that sensory substitution based on intraneural stimulation can deliver both position feedback and tactile feedback simultaneously and in real time,” explains Micera. “The brain has no problem combining this information, and patients can process both types in real time with excellent results.”

Intraneural stimulation re-establishes the flow of external information using electric pulses sent by electrodes inserted directly into the amputee’s stump. Patients then have to undergo training to gradually learn how to translate those pulses into proprioceptive and tactile sensations.

This technique enabled two amputees to regain high proprioceptive acuity, with results comparable to those obtained in healthy subjects. The simultaneous delivery of position information and tactile feedback allowed the two amputees to determine the size and shape of four objects with a high level of accuracy (75.5%).

“These results show that amputees can effectively process tactile and position information received simultaneously via intraneural stimulation,” says Edoardo D’Anna, EPFL researcher and lead author of the study.

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Materials provided by Ecole Polytechnique Fédérale de Lausanne. Note: Content may be edited for style and length.


Journal Reference:

  1. Edoardo D’Anna, Giacomo Valle, Alberto Mazzoni, Ivo Strauss, Francesco Iberite, Jérémy Patton, Francesco M. Petrini, Stanisa Raspopovic, Giuseppe Granata, Riccardo Di Iorio, Marco Controzzi, Christian Cipriani, Thomas Stieglitz, Paolo M. Rossini, Silvestro Micera. A closed-loop hand prosthesis with simultaneous intraneural tactile and position feedback. Science Robotics, 2019; 4 (27): eaau8892 DOI: 10.1126/scirobotics.aau8892
Source of the Article: Ecole Polytechnique Fédérale de Lausanne. “A prosthetic that restores the sense of where your hand is.” ScienceDaily. ScienceDaily, 21 February 2019. <www.sciencedaily.com/releases/2019/02/190221110357.htm>.

New tech may make prosthetic hands easier for patients to use

Researchers have developed new technology for decoding neuromuscular signals to control powered, prosthetic wrists and hands. The work relies on computer models that closely mimic the behavior of the natural structures in the forearm, wrist and hand. The technology could also be used to develop new computer interface devices for applications such as gaming and computer-aided design (CAD).

Credit: Lizhi Pan, NC State University

The technology has worked well in early testing but has not yet entered clinical trials — making it years away from commercial availability. The work was led by researchers in the joint biomedical engineering program at North Carolina State University and the University of North Carolina at Chapel Hill.

Current state-of-the-art prosthetics rely on machine learning to create a “pattern recognition” approach to prosthesis control. This approach requires users to “teach” the device to recognize specific patterns of muscle activity and translate them into commands — such as opening or closing a prosthetic hand.

“Pattern recognition control requires patients to go through a lengthy process of training their prosthesis,” says He (Helen) Huang, a professor in the joint biomedical engineering program at North Carolina State University and the University of North Carolina at Chapel Hill. “This process can be both tedious and time-consuming.

“We wanted to focus on what we already know about the human body,” says Huang, who is senior author of a paper on the work. “This is not only more intuitive for users, it is also more reliable and practical.

“That’s because every time you change your posture, your neuromuscular signals for generating the same hand/wrist motion change. So relying solely on machine learning means teaching the device to do the same thing multiple times; once for each different posture, once for when you are sweaty versus when you are not, and so on. Our approach bypasses most of that.”

Instead, the researchers developed a user-generic, musculoskeletal model. The researchers placed electromyography sensors on the forearms of six able-bodied volunteers, tracking exactly which neuromuscular signals were sent when they performed various actions with their wrists and hands. This data was then used to create the generic model, which translated those neuromuscular signals into commands that manipulate a powered prosthetic.

“When someone loses a hand, their brain is networked as if the hand is still there,” Huang says. “So, if someone wants to pick up a glass of water, the brain still sends those signals to the forearm. We use sensors to pick up those signals and then convey that data to a computer, where it is fed into a virtual musculoskeletal model. The model takes the place of the muscles, joints and bones, calculating the movements that would take place if the hand and wrist were still whole. It then conveys that data to the prosthetic wrist and hand, which perform the relevant movements in a coordinated way and in real time — more closely resembling fluid, natural motion.

“By incorporating our knowledge of the biological processes behind generating movement, we were able to produce a novel neural interface for prosthetics that is generic to multiple users, including an amputee in this study, and is reliable across different arm postures,” Huang says.

And the researchers think the potential applications are not limited to prosthetic devices.

“This could be used to develop computer-interface devices for able-bodied people as well,” Huang says. “Such as devices for gameplay or for manipulating objects in CAD programs.”

In preliminary testing, both able-bodied and amputee volunteers were able to use the model-controlled interface to perform all of the required hand and wrist motions — despite having very little training.

“We’re currently seeking volunteers who have transradial amputations to help us with further testing of the model to perform activities of daily living,” Huang says. “We want to get additional feedback from users before moving ahead with clinical trials.

“To be clear, we are still years away from having this become commercially available for clinical use,” Huang stresses. “And it is difficult to predict potential cost, since our work is focused on the software, and the bulk of cost for amputees would be in the hardware that actually runs the program. However, the model is compatible with available prosthetic devices.”

The researchers are also exploring the idea of incorporating machine learning into the generic musculoskeletal model.

“Our model makes prosthetic use more intuitive and reliable, but machine learning could allow users to gain more nuanced control by allowing the program to learn each person’s daily needs and preferences and better adapt to a specific user in the long term,” Huang says.

Date of the article:May 22, 2018

Source of the article:North Carolina State University