Tag Archives: osseointegration

Living with a mind-controlled prosthetic

This could be described as the second half of an October 10, 2014 post (Mind-controlled prostheses ready for real world activities). Five and a half years later, Sweden’s Chalmers University of Technology has announced mind-controlled prosthetics in daily use that feature the sense of touch. From an April 30, 2020 Chalmers University of Technology press release (also on EurekAlert but published April 29, 2020) by Johanna Wilde,

For the first time, people with arm amputations can experience sensations of touch in a mind-controlled arm prosthesis that they use in everyday life. A study in the New England Journal of Medicine reports on three Swedish patients who have lived, for several years, with this new technology – one of the world’s most integrated interfaces between human and machine.

See the film: “The most natural robotic prosthesis in the world” [Should you not have Swedish language skills, you can click on the subtitle option in the video’s settings field]

The advance is unique: the patients have used a mind-controlled prosthesis in their everyday life for up to seven years. For the last few years, they have also lived with a new function – sensations of touch in the prosthetic hand. This is a new concept for artificial limbs, which are called neuromusculoskeletal prostheses – as they are connected to the user’s nerves, muscles, and skeleton.

The research was led by Max Ortiz Catalan, Associate Professor at Chalmers University of Technology, in collaboration with Sahlgrenska University Hospital, University of Gothenburg, and Integrum AB, all in Gothenburg, Sweden. Researchers at Medical University of Vienna in Austria and the Massachusetts Institute of Technology in the USA were also involved.

“Our study shows that a prosthetic hand, attached to the bone and controlled by electrodes implanted in nerves and muscles, can operate much more precisely than conventional prosthetic hands. We further improved the use of the prosthesis by integrating tactile sensory feedback that the patients use to mediate how hard to grab or squeeze an object. Over time, the ability of the patients to discern smaller changes in the intensity of sensations has improved,” says Max Ortiz Catalan.

“The most important contribution of this study was to demonstrate that this new type of prosthesis is a clinically viable replacement for a lost arm. No matter how sophisticated a neural interface becomes, it can only deliver real benefit to patients if the connection between the patient and the prosthesis is safe and reliable in the long term. Our results are the product of many years of work, and now we can finally present the first bionic arm prosthesis that can be reliably controlled using implanted electrodes, while also conveying sensations to the user in everyday life”, continues Max Ortiz Catalan.

Since receiving their prostheses, the patients have used them daily in all their professional and personal activities.

The new concept of a neuromusculoskeletal prosthesis is unique in that it delivers several different features which have not been presented together in any other prosthetic technology in the world:

[1] It has a direct connection to a person’s nerves, muscles, and skeleton.

[2] It is mind-controlled and delivers sensations that are perceived by the user as arising from the missing hand.

[3] It is self-contained; all electronics needed are contained within the prosthesis, so patients do not need to carry additional equipment or batteries.

[4] It is safe and stable in the long term; the technology has been used without interruption by patients during their everyday activities, without supervision from the researchers, and it is not restricted to confined or controlled environments.

The newest part of the technology, the sensation of touch, is possible through stimulation of the nerves that used to be connected to the biological hand before the amputation. Force sensors located in the thumb of the prosthesis measure contact and pressure applied to an object while grasping. This information is transmitted to the patients’ nerves leading to their brains. Patients can thus feel when they are touching an object, its characteristics, and how hard they are pressing it, which is crucial for imitating a biological hand.

“Currently, the sensors are not the obstacle for restoring sensation,” says Max Ortiz Catalan. “The challenge is creating neural interfaces that can seamlessly transmit large amounts of artificially collected information to the nervous system, in a way that the user can experience sensations naturally and effortlessly.”
The implantation of this new technology took place at Sahlgrenska University Hospital, led by Professor Rickard Brånemark and Doctor Paolo Sassu. Over a million people worldwide suffer from limb loss, and the end goal for the research team, in collaboration with Integrum AB, is to develop a widely available product suitable for as many of these people as possible.

“Right now, patients in Sweden are participating in the clinical validation of this new prosthetic technology for arm amputation,” says Max Ortiz Catalan. “We expect this system to become available outside Sweden within a couple of years, and we are also making considerable progress with a similar technology for leg prostheses, which we plan to implant in a first patient later this year.”

More about: How the technology works:

The implant system for the arm prosthesis is called e-OPRA and is based on the OPRA implant system created by Integrum AB. The implant system anchors the prosthesis to the skeleton in the stump of the amputated limb, through a process called osseointegration (osseo = bone). Electrodes are implanted in muscles and nerves inside the amputation stump, and the e-OPRA system sends signals in both directions between the prosthesis and the brain, just like in a biological arm.

The prosthesis is mind-controlled, via the electrical muscle and nerve signals sent through the arm stump and captured by the electrodes. The signals are passed into the implant, which goes through the skin and connects to the prosthesis. The signals are then interpreted by an embedded control system developed by the researchers. The control system is small enough to fit inside the prosthesis and it processes the signals using sophisticated artificial intelligence algorithms, resulting in control signals for the prosthetic hand’s movements.

The touch sensations arise from force sensors in the prosthetic thumb. The signals from the sensors are converted by the control system in the prosthesis into electrical signals which are sent to stimulate a nerve in the arm stump. The nerve leads to the brain, which then perceives the pressure levels against the hand.

The neuromusculoskeletal implant can connect to any commercially available arm prosthesis, allowing them to operate more effectively.

More about: How the artificial sensation is experienced:

People who lose an arm or leg often experience phantom sensations, as if the missing body part remains although not physically present. When the force sensors in the prosthetic thumb react, the patients in the study feel that the sensation comes from their phantom hand. Precisely where on the phantom hand varies between patients, depending on which nerves in the stump receive the signals. The lowest level of pressure can be compared to touching the skin with the tip of a pencil. As the pressure increases, the feeling becomes stronger and increasingly ‘electric’.

I have read elsewhere that one of the most difficult aspects of dealing with a prosthetic is the loss of touch. This has to be exciting news for a lot of people. Here’s a link to and a citation for the paper,

Self-Contained Neuromusculoskeletal Arm Prostheses by Max Ortiz-Catalan, Enzo Mastinu, Paolo Sassu, Oskar Aszmann, and Rickard Brånemark. N Engl J Med 2020; 382:1732-1738 DOI: 10.1056/NEJMoa1917537 Published: April 30, 2020

This paper is behind a paywall.

Mind-controlled prostheses ready for real world activities

There’s some exciting news from Sweden’s Chalmers University of Technology about prosthetics. From an Oct. 8, 2014 news item on ScienceDaily,

For the first time, robotic prostheses controlled via implanted neuromuscular interfaces have become a clinical reality. A novel osseointegrated (bone-anchored) implant system gives patients new opportunities in their daily life and professional activities.

In January 2013 a Swedish arm amputee was the first person in the world to receive a prosthesis with a direct connection to bone, nerves and muscles. …

An Oct. 8, 2014 Chalmers University press release (also on EurekAlert), which originated the news item, provides more details about the research and this ‘real world’ prosthetic device,

“Going beyond the lab to allow the patient to face real-world challenges is the main contribution of this work,” says Max Ortiz Catalan, research scientist at Chalmers University of Technology and leading author of the publication.

“We have used osseointegration to create a long-term stable fusion between man and machine, where we have integrated them at different levels. The artificial arm is directly attached to the skeleton, thus providing mechanical stability. Then the human’s biological control system, that is nerves and muscles, is also interfaced to the machine’s control system via neuromuscular electrodes. This creates an intimate union between the body and the machine; between biology and mechatronics.”

The direct skeletal attachment is created by what is known as osseointegration, a technology in limb prostheses pioneered by associate professor Rickard Brånemark and his colleagues at Sahlgrenska University Hospital. Rickard Brånemark led the surgical implantation and collaborated closely with Max Ortiz Catalan and Professor Bo Håkansson at Chalmers University of Technology on this project.

The patient’s arm was amputated over ten years ago. Before the surgery, his prosthesis was controlled via electrodes placed over the skin. Robotic prostheses can be very advanced, but such a control system makes them unreliable and limits their functionality, and patients commonly reject them as a result.

Now, the patient has been given a control system that is directly connected to his own. He has a physically challenging job as a truck driver in northern Sweden, and since the surgery he has experienced that he can cope with all the situations he faces; everything from clamping his trailer load and operating machinery, to unpacking eggs and tying his children’s skates, regardless of the environmental conditions (read more about the benefits of the new technology below).

The patient is also one of the first in the world to take part in an effort to achieve long-term sensation via the prosthesis. Because the implant is a bidirectional interface, it can also be used to send signals in the opposite direction – from the prosthetic arm to the brain. This is the researchers’ next step, to clinically implement their findings on sensory feedback.

“Reliable communication between the prosthesis and the body has been the missing link for the clinical implementation of neural control and sensory feedback, and this is now in place,” says Max Ortiz Catalan. “So far we have shown that the patient has a long-term stable ability to perceive touch in different locations in the missing hand. Intuitive sensory feedback and control are crucial for interacting with the environment, for example to reliably hold an object despite disturbances or uncertainty. Today, no patient walks around with a prosthesis that provides such information, but we are working towards changing that in the very short term.”

The researchers plan to treat more patients with the novel technology later this year.

“We see this technology as an important step towards more natural control of artificial limbs,” says Max Ortiz Catalan. “It is the missing link for allowing sophisticated neural interfaces to control sophisticated prostheses. So far, this has only been possible in short experiments within controlled environments.”

The researchers have provided an image of the patient using his prosthetic arm in the context of his work as a truck driver,

[downloaded from http://www.chalmers.se/en/news/Pages/Mind-controlled-prosthetic-arms-that-work-in-daily-life-are-now-a-reality.aspx]

[downloaded from http://www.chalmers.se/en/news/Pages/Mind-controlled-prosthetic-arms-that-work-in-daily-life-are-now-a-reality.aspx]

The news release offers some additional information about the device,

The new technology is based on the OPRA treatment (osseointegrated prosthesis for the rehabilitation of amputees), where a titanium implant is surgically inserted into the bone and becomes fixated to it by a process known as osseointegration (Osseo = bone). A percutaneous component (abutment) is then attached to the titanium implant to serve as a metallic bone extension, where the prosthesis is then fixated. Electrodes are implanted in nerves and muscles as the interfaces to the biological control system. These electrodes record signals which are transmitted via the osseointegrated implant to the prostheses, where the signals are finally decoded and translated into motions.

There are also some videos of the patient demonstrating various aspects of this device available here (keep scrolling) along with more details about what makes this device so special.

Here’s a link to and a citation for the research paper,

An osseointegrated human-machine gateway for long-term sensory feedback and motor control of artificial limbs by Max Ortiz-Catalan, Bo Håkansson, and Rickard Brånemark. Sci Transl Med 8 October 2014: Vol. 6, Issue 257, p. 257re6 Sci. Transl. Med. DOI: 10.1126/scitranslmed.3008933

This article is behind a paywall and it appears to be part of a special issue or a special section in an issue, so keep scrolling down the linked to page to find more articles on this topic.

I have written about similar research in the past. Notably, there’s a July 19, 2011 post about work on Intraosseous Transcutaneous Amputation Prosthesis (ITAP) and a May 17, 2012 post featuring a video of a woman reaching with a robotic arm for a cup of coffee using her thoughts alone to control the arm.