The DeTOP (Dexterous Transradial Osseointegrated Prosthesis with neural control and sensory feedback) project [link] [link]1 wants to provide an osseointegrated human-machine gateway (OHMG) for transradial amputation, according to its brochure 2 . This is a short review of the project.
- Research premise and goal
- What is the goal: building an osseointegrated human-machine gateway OHMG for transradial amputation
- What are typical myoelectric control error rates
- Research output
Research premise and goal
The research premise of this project states that "Despite decades of research and development on artificial limbs and neural interfaces, amputees continue to use technology for powered prostheses developed over 40 years ago, namely myoelectric prostheses controlled via surface electrodes".
They then state that they want to develop for transradial amputees specifically 3 .
This seems quite remarkable as a claim, because as stated, it is wrong, from where I am standing, in a sense that it creates the wrong impression totally. What exactly is the problem with something that is 40 years old: electricity used on an arm stump? Is that so bad? That idea certainly is a few decades old, but the researchers themselves keep using electricity on arm stumps, so they seem not do anything different in terms of a general concept. Using a hand shape for gripper as terminal device? That idea is extremely old even, but the researchers here seem happy with prosthetic "hands", instead, they did not seem to have written any split hook studies, which they could have done easily if they were after something more modern at all [link]. Using any type of control to power, actuate, a terminal device as such is not new either, but I see nothing wrong with using an idea that is old and good, also the researchers here did not seem to deviate from using some type of control even though the idea of having some type of control is really old. So what again was the problem that something was over 40 years old? Or was it more a problem that bloated technology that does not really work should be improved - but then, why not state exactly that.
Then, amputees in a comprehensive sense as declared here, arm amputees, to be a bit more precise, to an overwhelming majority of about 80-85% at least, do not wear a prosthesis at all, a quite realistic estimate that is. These researchers however state that "amputees continue to use technology for powered prostheses developed over 40 years ago, namely myoelectric prostheses controlled via surface electrodes" when really arm amputees generally mostly do not use any prosthetic technology at all. They could have written "arm amputees mostly do not use any prosthetic arm at all, that tells us how little advanced our current technologies really are - and in an overall weighting of cost against benefit, the arm amputees are often right and correct to reject prosthetic arms". A logical consequence of a well thought out research would logically then address that cost versus benefit problem first, while bolting thin metal pieces into brittle thin forearm stump bones and having open wounds gape and ooze forever to start with does not seem to be a particularly cost-effective way at all, then using some 80 000 to 120 000 USD priced prosthetic hands there, with the bolts sticking out also messing up one's intimate life - really, who reviews these ideas? Maybe see why prosthetists and manufacturers charge so much for their devices and see exactly where money is wasted.
So, we tend to have around 85% estimated non-wearers of prosthetic arms , and the remaining 15% seems to be split between wearing a cosmetic / passive, body-powered and myoelectric prosthesis.
There, body-powered technology has certainly seen the most and most relevant technical improvements over the decades whereas myoelectric control quality actually has slightly deteriorated over the past 40 years, if one randomly pulls out studies across these four decades (link), and so also the listed studies of this project (below) did not seem to have produced what I see as usefully accurate grip control rates either. Don't get me wrong: I do not blame the researchers from not being able to milk better signal from arm amputees' stumps. Most likely, no one can do that - because if research about myoelectric control error rates established something over the last 40 years or so, then they showed in summary, that myoelectric signals are often of relatively low quality and no usefully low grip error rates can be achieved at all. At least, no one did it since the introduction of the Russian Arm in 1960, which makes the time span 61 years now. Overall, we as arm amputees appear to be dependent and fragile, particularly as far as our high-tech prostheses are concerned. Like, (link) Ossur decided to pull the plug on my ~80 000 CHF costing iLimb's Android and Windows "biosim" software - without announcement - a tiny example of where things are at, also in 2020 / 2021. In other words, despite having been paid a superbly premium price, the manufacturer decides when to ground the device. That is where we - as a wearer of devices - are factually vulnerable. This project does not address this real aspect at all. Some other attempts to allegedly improve this dependency apparently addressed the issue of sockets, but bottom line was that they did not reduce but, in my view and opinion, shift and increase the amputee's dependency and fragility. Osseointegration as a step towards socket-free prosthesis causes a chronic open skin wound, with relatively easy access of bacteria to the bone marrow, which depending on lifestyle (I really love my public pool swims for example) is surely a problem, and the implants particularly for transradial amputees are thin and our stump bones assumedly are mostly brittle, all the while we can use sockets to lift, pull, yank and work hard, which appears to spell out as relatively high fracture risks, which depending on work and lifestyle also is a problem. The technology of nerve implants does not generally appear overly stable, all the while all of this due to these problems remains experimental and adds absolutely mind-boggling expenses to be privately paid to already insane costs of myoelectric hands, as that is the type of device to use in this context. So the research premise clearly follows the "riding of a dead horse" and the "vicious cycle" of increased "featuritis" as outlined already before these people started [link]. This raises the question exactly who reviewed and approved of this silly project idea. I mean, they could have called me and I would have told them alright.
What is the goal: building an osseointegrated human-machine gateway OHMG for transradial amputation
The goal of the project, as declared there, is claimed to be "the osseointegrated human-machine gateway for trans-radial amputees".
So the predominant actual issues to be solved here from my view are:
- A - torque and fracture risk for transradial amputees with osseointegration (link)
- B - infection risk in trans-radial amputees with osseointegration
- C - functional stability of the implant in trans-radial amputees with osseointegration
- D - lowering repair frequency and maintenance volume for trans-radial amputees, as the apparently bad quality of traditional prosthesis due their technical design being 40 years of age is deplored by these researchers
What are typical myoelectric control error rates
Myoelectric control is junk to begin with [link] - and while this is a tongue-in-cheek rant following the car view of Alex Roy, there is technical truth in that. You have to realize where you are here - this is a technical right below elbow amputee issues site, and opinions are mine. So myoelectric being junk, is not new, or unknown, we knew that there was something up already, says, in 2016. So, objects one holds or transports drop "all the time" - get someone with a myoelectric arm to unload your dishwasher means to start saving up or re-using plastic cups from fast-food chains.
Approximating true cost of faulty grip control
To approximate true cost of error rates [see this link also], assume that I unload a dishwasher with 30 items (that could break) every two days, and each costs 8.00 USD. The total sum moved per year then costs 43 800 USD and dropping 1% of these will come to 438 USD.
So in such a realistic model, the actual cost of lost porcelain and glass in USD will then come to 438 USD per percent of a recognition rate of less than 100%. This however means that an error rate of 21.3% (see study below) costs the amputee that uses the prosthesis for that task an equivalent of about 9230 USD per year. And R&D wonders why we may prefer not using the prosthesis for such work, obviating the role of the prosthesis in the process? So maybe, just maybe, that is why we recommend error rates that range in industrial manufacturing error target ranges of three sigma or six sigma 4.
So a device offering three-sigma grip accuracy (93,3% - error rate of 6,7%) is entirely out of reach for myoelectric prostheses and can only be achieved with a well-built body-powered arm, this still will add 2934 USD in wasted porcelain and glass to the amputee's household bill. Even a four sigma quality (entirely unachievable for myoelectric control) (an error rate of 0,6%) will set you back by 263 USD in dropped and damaged goods. Five sigma (99,97% correct recognition - 0,03 % error rate) will cost around 13 USD per year - that is acceptable but ... not perfect. This will cause still almost two broken items per year, it amounts to about eight lost cups or plates or glasses in five years, possibly a whole set of plates or so.
But why not add more real-life aspects to further sharpen the senses.
If I shoot about 340 digital photos a month, quite a realistic number, I just checked, this will be 4080 shots per year. So if my camera costs 400 USD and it dies after 3 falls, then I divide the total shots taken by 300, and multiply the result with 4o0. That is what 1% error rate of grip control costs me, and with this model it will be 5440 USD. So a four sigma error for grip controls will cost me an equivalent of 0,6% if I take photos at that rate, still over 3000 bucks. With five sigma, about 163 bucks per year in damaged cameras. And I did drop cell phones and cameras and dishes due to prosthesis failure. And it was expensive. And, that is how I know. So why you think I use body-powered arms? Really, seriously.
So a manufacturer even managing to offer five sigma grip control errors, that is, errors of 0.03% or less, is not to be overly proud - and yet, this is unthinkable for myoelectric control, none of these studies even manage 1 sigma.
They are deep in the ranges of entirely unacceptable levels of error! On top, realistic daily myoelectric control error rates are around 5 to 30%. No wonder some of the dedicated myoelectric arm wearers just have overuse problems of their other arm - because you really end up doing the work with that arm that works reliably, because you won't crash dishes costing hundreds our thousands of dollars per year after all.
There seem to be a total of 24 papers [link] until today (28.05.2021) (they probably listed one twice?).
This paper of the research group does examine one (1) transradial arm amputee but misses any of A, B, C and D
I. Boni, J. Millenaar, M. Controzzi, M. Ortiz-Catalan, Restoring Natural Forearm Rotation in Transradial Osseointegrated Amputees – IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 26, 2018 5
These papers of the research group do not at all address any of A, B, C and D
M. Ortiz-Catalan, E. Mastinu, C. Greenspon, and S. Bensmaia, “Chronic use of a sensitized bionic hand does not remap the sense of touch”, Cell Reports, 2020 6
A. Middleton, M. Ortiz-Catalan, “Neuromusculoskeletal Arm Prostheses: Personal and Social Implications of Living With an Intimately Integrated Bionic Arm” – Frontiers of Neurobotics, 2020 7
M. Ortiz-Catalan, E. Mastinu, P. Sassu, O. Aszmann, and R. Brånemark, “Self-contained Neuromusculoskeletal Arm Prostheses” – New England Journal of Medicine, 2020 8
E. Mastinu, L. Engels, F. Clemente, M. Dione, P. Sassu, O. Aszmann, R. Brånemark, B. Håkansson, M. Controzzi, J. Wessberg, C. Cipriani, and M. Ortiz-Catalan, “Neural feedback strategies to improve grasping coordination in neuromusculoskeletal prostheses” – Scientific Reports, 2020 9
L. Cappello , W. Alghilan, M. Gabardi, D. Leonardis, M. Barsotti, A. Frisoli, and C. Ciprian, Continuous supplementary tactile feedback can be applied (and then removed) to enhance precision manipulation – Journal of NeuroEngineering and Rehabilitation 17, 120 (2020) 10
C. Gunter, J. Delbeke, M. Ortiz-Catalan, “Safety of long-term electrical peripheral nerve stimulation: review of the state of the art” – Journal of NeuroEngineering and Rehabilitation, vol. 16, no. 1, pp. 1-13, 2019 11
L. Engels, A. Shehata, E. Scheme, J. Sensinger, C. Cipriani, When Less is More—Discrete Tactile Feedback Dominates Continuous Audio Biofeedback in the Integrated Percept while Controlling a Myoelectric Prosthetic Hand – Frontiers in Neuroscience, 2019, online 12
N. Malesevic, A. Björkman, G. S. Andersson, A. Matran-Fernandez, L. Citi, C. Cipriani, C. Antfolk, A database of multi-channel intramuscular electromyogram signals during isometric hand muscles contractions – Scientific Data 13
A. Matran-Fernandez, I. J. Rodríguez Martínez, R. Poli, C. Cipriani, L. Citi, SEEDS, simultaneous recordings of high-density EMG and finger joint angles during multiple hand movements – Scientific Data, vol. 6 14
A. Olsson, P. Sager, E. Andersson, A. Björkman, G. S. Andersson, N. Malešević, C. Antfolk, Extraction of Multi-Labelled Movement Information from the Raw HD-sEMG Image with Time-Domain Depth – Scientific Reports 15
M. Ortiz-Catalan, J. Wessberg, E. Mastinu, A. Naber, and R. Brånemark, “Patterned Stimulation of Peripheral Nerves Produces Natural Sensations with Regards to Location but Not Quality” – IEEE Transactions on Medical Robotics and Bionics, August 2019 16
E. Mastinu, F. Clemente, P. Sassu, O. Aszmann, R. Brånemark, B. Håkansson, M. Controzzi, C. Cipriani, and M. Ortiz-Catalan, Grip control and motor coordination with implanted and surface electrodes while grasping with an osseointegrated prosthetic hand – Journal of NeuroEngineering and Rehabilitation, 2019 17
L. A. Celi, L. Citi, M. Ghassemi, and T. J. Pollard, The PLOS ONE collection on machine learning in health and biomedicine: Towards open code and open data – PloS ONE 14, no. 1 (2019): e0210232 18
N. Malesevic, G. Andersson, A. Björkman, M. Controzzi, C. Cipriani, C. Antfolk, Instrumented platform for assessment of isometric hand muscles contractions – Measurement Science and Technology, 2019 - 19
C. Günter, J. Delbeke, M. Ortiz-Catalan, Safety of long-term electrical peripheral nerve stimulation: review of the state of the art – Journal of NeuroEngineering and Rehabilitation, vol. 16, no. 1, pp. 13, 2019 20
G. Kanitz, F. Montagnani, M. Controzzi, C. Cipriani, Compliant Prosthetic Wrists Entail More Natural Use Than Stiff Wrists During Reaching, Not (Necessarily) During Manipulation – IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 26, no. 7, pp. 1407-1413, 2018 21
A. Shehata, L. Engels, M. Controzzi, C. Cipriani, E. Scheme, J. Sensinger, Improving internal model strength and performance of prosthetic hands using augmented feedback – Journal of NeuroEngineering and Rehabilitation, vol. 2018, pp. 70, 2018 22
M. Aboseria, F. Clemente, L. Engels, C. Cipriani, Discrete Vibro-Tactile Feedback Prevents Object Slippage in Hand Prostheses More Intuitively than other Modalities – IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 26, no. 8, pp. 1577-1584, 2018 23
N. Malešević, D. Marković, G. Kanitz, M. Controzzi, C. Cipriani, C. Antfolk, Vector Autoregressive Hierarchical Hidden Markov Models for Extracting Finger Movements Using Multichannel Surface EMG Signals – Complexity, vol. 2018, pp. 1-12, 2018 24
E. Mastinu, J. Ahlberg, E. Lendaro, B. Håkansson, M. Ortiz-Catalan, An alternative myoelectric pattern recognition approach for the control of hand prostheses: A case study of use in daily life by a dysmelia subject – IEEE Journal of Translational Engineering in Health and Medicine, vol. 6, 2018 25
A. Thesleff, R. Brånemark, B. Håkansson, M. Ortiz-Catalan, Biomechanical Characterisation of Bone-anchored Implant Systems for Amputation Limb Prostheses: A Systematic Review – Annals of Biomedical Engineering, vol. 46, no. 3, pp. 377–391, 2018 26
N. Nillson, B. Håkansson, M. Ortiz-Catalan, Classification complexity in myoelectric pattern recognition – Journal of NeuroEngineering and Rehabilitation, vol. 14, no. 68, 2017 27
F. Clemente, B. Håkansson, C. Cipriani, J. Wessberg, K. Kulbacka-Ortiz, R. Brånemark, K.-J. Fredén Jansson, M. Ortiz-Catalan, Touch and hearing mediate osseoperception – Scientific Reports, vol. 7, no. 45363, pp. 11, 2017 28
F. Montagnani, M. Controzzi, C. Cipriani, Indipendent Long Fingers are not Essential for a Grasping Hand – Scientific Reports, vol. 6, no. 35545, pp. 1-9, 2016 - 29
This project cannot possibly have been reviewed and approved by professionals with specific knowledge in the domain of successfully fitting transradial arm amputees with prosthetic arms, particularly those with little tolerance to experimental, very risky (in the long run) and massively overpriced usually privately paid surgery, combined with a still unsatisfactory grip reliability those with little to no tolerance for overly fragile terminal devices, in need for a prosthesis that survives real work without extreme or even insane requirements for virtually constant repairs. They may have sent their project to fans or friends, or to reviewers that do not know anything about transradial amputees and that do not know how some of us consume materials, smoke up materials, go through materials, like butter - I believe they did not send it to people that really understand claims and assertions in upper extremity prosthetics in relation to real work and real life - where you want full reliability up to 40-60 kg minimum, 12-14 hours a day, at least 6 months without any loss of function or need for service/repair. The claims seem really intriguing as explained above, but there are no visible developments for a wider trans-radial amputee audience so far in terms of the issues that I listed as A, B, C, and D, and that all are relevant from a real-life view with and on prosthetic arms. I mean, I would be surprised if the researchers identified some people in, say, construction or sanitary installation work, or maybe farming, where one is surrounded by "contaminants", and works one's butt off, to allow some osseointegration plus nerve connection tests - of course, never say never, but the research premise as such from where I am standing (and you came here for my opinion, if anything) is ludicrous. The people that do suffer from prosthetic arm breakdowns in particular, the ones that suffer most, as measured maybe by how often, are those that load their arms the most, and that are people in excessive loading type jobs.
This Horizon 2020 project is an example of a well-funded project that did not appear to achieve a bit of what it claimed, at least from what we can see just as of yet, and as far as the researchers have shown. This is not at all a surprise. A long time ago already as rumors go, totally unfounded grapevine and such (but then this is an opinion website where we certainly may consider the obscure, after all, consider any possibly obscure aspects of this project?), the reason that robotics institutes may have had "prosthetic / robot hands" on display or as student projects was - so rumors - not that their technical approach to getting these right was so earth-shatteringly proficient - no. It was just something that looked nice, and also, there was a bit of research money - not much, but an extra bit - from disability research. And these robot hands, allegedly for the disabled, seemed to appear so relatable. There, disability research review boards, probably to this day, in all assumption may have veen, still are I guess, jocked full of people that believe that just this next stupid myoelectric project will do what the one before did not - save the amputees, give the amputees "back" a hand. Why they believe that we do not know. But these often were student projects, nothing too respectable in terms of market maturity - and these projects were carried on such a level simply because on one hand they allowed for neat photos, but also, there was nothing to gain from a hardcore robotics perspective - the constraints too high, the degrees of freedom too high, the possibilities technically not good enough for that combination, and the application domain was never real fun. The real art in prosthetic arms is to not get grip reliability to 98%, but far higher, to past six sigma. Incidentally, autonomous driving currently seems to hit that same speed bump. So rumors seemed to have it that no self-respecting robotics researcher would seriously pursue the prosthetic robot hand myth any further than making nice images for a poster or running a demo with a 7 kg battery pack and a 5 kg motor pack. And with that, tradition had it - all according to rumors and hearsay - that prosthetic hand research never really was meant seriously, not in a sense that "seriously" is seen from my, real work / real application / real load perspective. And if this Horizon 2021 project relaxedly f0llows tradition, then we do not have to fear any serious paradigm shifts. So of course I just listed some rumors and speculations and who knows - you tell me though, just how serious the real life problems are addressed, and where the test are that examine, understand and document these problems vice versa the research that directly addresses these.
Because then, this Horizon 2021 project (at least so far) appears to be a superb showcase for exactly why it is 2021, and by far the best if not only prosthetic type to use for real work as right below-elbow (i.e. transradial) amputee still is a body-powered split hook or gripper. By so very far. Probably will be also in 2025, or 2030, who knows? If you do that research, you tell me!? With a body-powered split-hook, we have no such distal center of gravity issues, no such control issues, no such suspension issues that we need to drill bolts into thin forearm bones, no similarly insanely high cost issues, no overly extreme repair/maintenance issues, no such bone fracture risks and no open skin wounds to perpetually nurse, as in osseointegration, and who knows how long the nerve implants last until they need to be dug out again. And I do not blame the researchers for writing mostly about their three transhumeral amputees and some stuff about "healthy" study subjects, and practically not a word about transradial amputee developments for osseointegration: because problems A, B, C and D tend to become costly and cumbersome even with regard to expensive medicine - particularly if you want to look at a "wider audience and clientele" that sooner or later, invariably, also will contain people you quite frankly do not want to equip with delicate fragile myoelectric devices using brittle thin bone implants sticking out through open oozing wounds.
May we all look forward to their relevant next paper titled "osseointegrated human-machine gateway in 30 trans-radial amputees, a 3-year follow-up study with particular regard to infections and fractures". And until all issues for real work and real rehabilitation for real overuse issues and bimanual activities etc are resolved, why not wear a body-powered split hook arm, one that is built well though.
- Involved researchers / developers, according to [link]:
I included a link for a Google scholar search with the name of that person in association with the search term transradial amputation, since 2020, just to see right quick what if anything they wrote up about that subject matter which in essence seems to pertain closely to the project's core subject claim.
Scuola Superiore Sant’Anna
- Christian Cipriani [google scholar search]
Coordinator of DeTOP
- Marco Controzzi [google scholar search]
Assistant Professor, Project Manager
- Andrea Mannini
- Leonardo Cappello
- Michele Bacchereti
- Itzel Jared Rodriguez Martinez
- Leonard Engels
University of Gothenburg
- Johan Wessberg [google scholar search]
- Rickard Brånemark [google scholar search]
- Mariama Dione
Prensilia SRL [link]
- Diego Barone
- Lorenzo Bassi Luciani
- Francesco Clemente
- Neri Pierotti
- Integrum AB
- Max Ortiz Catalan
- Marta Björnsdóttir
- Enzo Mastinu
- Jason Millenaar
- Christian Antfolk [google scholar search]
- Anders Björkman
- Nebojša Malešević
Centre Suisse d’Electronique et de Microtechnique
- Jean-Dominique Decotignie [google scholar search]
Head of Embedded and Wireless Systems section
- Pierre-François Rüedi
Head of Integrated Smart Sensing section
- Stephane Emery
Head of System-on-Chip section
- Marc Pons Solé
University of Essex
- Luca Citi [google scholar search]
- Alberto Garcia-Vellisca
Senior research officer
- Riccardo Poli
- Ana Matrán-Fernández
Istituto Ortopedico Rizzoli
- Stefano Zaffagnini [google scholar search]
- Giulio Maria Marcheggiani Muccioli
- Tommaso Roberti Di Sarsina
- Laura Bragonzoni
Campus Bio-Medico University of Rome
- Vincenzo Denaro [google scholar search]
- Giovanni Di Pino [google scholar search]
- Vincenzo Di Lazzaro [google scholar search]
- Rocco Papalia [google scholar search]
- Gianluca Vadalà [google scholar search]
- Ranieri Federico
- Lorenzo Alirio Diaz Balzani
- Alessandro Mioli
- Marco D’Alonzo
- Emma Falato
And if one does not believe these Google Scholar searches to be realistic, here are some prolific R&D people to compare the things they came up within the same period:
- Aaron Dollar [google scholar search]
- Linda Resnik [google scholar search]
- Claudio Castellini [google scholar search]
- Tamar Makin [google scholar search]
- Alix Chadwell [google scholar search]
- Christian Cipriani [google scholar search]
- DeTOP is a Research and Innovation project coordinated by The BioRobotics Institute of Scuola Superiore Sant’Anna. The project tar-gets people with reduced or absent hand sen-sorimotor capabilities, due to an amputation. It aims to develop and clinically implement ro-botic, sensing and long-term interfacing tech-nologies for the next-generation transradial prosthesis. Core of the system will be an os-seointegrated human-machine gateway (OHMG), able to create bidirectional physio-logical links between a human and a state-of-art dexterous robotic prosthesis with artificial skin. Key objective of DeTOP is to translate, exploit and appraise already proven technology for transhumeral amputation to the most fre-quent case of transradial amputation. The DeTOP consortium has pioneered the use of os-seointegration as a long-term stable solution for the direct skeletal attachment of limb prostheses. This technology, aside from providing an efficient mechanical coupling, which on its own has shown to improve prosthesis functionality and the patient’s quality of life, can also be used as a bidirectional com-munication interface between implanted electrodes and the prosthetic arm. The consortium has demonstrated that neuromuscular interfaces developed decades ago can considerably improve prosthetic control and functionality, if made clinically viable by having a long-term stable osseointegrated interface; namely, the osseointegrated human-machine gateway (OHMG). One patient with a trans-humeral amputation was the recipient of the OHMG system in January 2013. Despite decades of research and development on artificial limbs and neural interfaces, amputees continue to use tech-nology for powered prostheses developed over 40 years ago, namely myoelectric prostheses controlled via surface elec-trodes. Indeed, this is today the most reliable and clinically viable technique: the use of the electromyogram (EMG), i.e., the electrical activity produced by skeletal muscles as a by-product of normal muscle contraction, to control the move-ments of an electromechanical prosthesis. These prostheses are known for their poor functionality, poor controllability and poor sensory feedback. DeTOP will develop: The OHMG for transradial amputation A smart mechatronic coupling for connecting the OHMG to the prosthesis allowing safe wrist rotation A dexterous hand-wrist prosthesis with tactile sensors Physiological proportional myocontrol based on implanted electrodes Neural feedback for restoring natural tactile sensations Miniature Processing and Communication Nodes for control and sensory feedback Project name: DeTOP Grant number: H2020-ICT-687905 Starting date: 1st March 2016 Duration: 4 years Partners: 10 from 4 countries Funding: 5.1 M€
- Periodic Reporting for period 2 - DeTOP (Dexterous Transradial Osseointegrated Prosthesis with neural control and sensory feedback) - Reporting period: 2017-03-01 to 2018-08-31 - Summary of the context and overall objectives of the project The DeTOP project targets people with reduced or absent hand sensorimotor capabilities, due to an amputation. The latter is known to cause severe physical and psychosocial dysfunction. Besides the obvious inability to grasp and manipulate objects, as well as to sense the environment through the sense of touch and proprioception, the hand may no longer be used for gestures that normally support speech and emotional expressions. Additionally, the physical differences compared to other people can result in severe psychological problems. DeTOP aims to develop the next-generation transradial prosthesis by clinically implementing robotic, sensing and long-term interfacing technologies. Core of the system is an osseointegrated human-machine gateway (OHMG), able to create bidirectional links between a human and a robotic prosthesis. The OHMG is an enhancement of the OPRA Implant System (by Integrum AB, Sweden). The latter consists of two main components, the fixture and the abutment, mechanically secured by a screw so that the loads are directly transferred between the prosthesis and the skeleton. The OHMG also allows for bidirectional electrical communication, between the prosthesis and electrodes in the body (Fig. 1). Hence this system can provide direct electrical access with peripheral neuromuscular structures of the body, using suitable electrodes. For example, myoelectric signals recorded using epymisial electrodes can be collected and used for controlling a prosthesis; vice-versa cuff electrodes can convey sensory feedback to the brain, using an external stimulator connected to tactile sensors in the hand. Because of these unique features, today the OHMG is probably the most advanced technique for bidirectional neuromuscular interfacing, suited for the upper limb amputees, which was proven functional in the long term. Notably, the first recipient of the OHMG system is a patient with a trans-humeral amputation which was implanted in January 2013 – since then is using it. This successful case paved the way for DeTOP and now opens the door for the study and implementation of more natural and complete prostheses. The goal of DeTOP is to push the boundaries of this technology –made in Europe– and to make it clinically available to the largest population of upper limb amputees, namely transradial amputees. This objective will be targeted by developing a novel prosthetic hand with improved functionality, smart mechatronic devices/features for safe implantable technology, and by studying and assessing paradigms for natural control (action) and sensory feedback (perception) of the prosthesis through the OHMG. DeTOP will not only develop ready-to-use human-machine-interfaces and dexterous prostheses for the disabled; the interfaces and systems developed within the project will be chronically implanted in 3 selected patients which will take the systems at home. In particular, the new prostheses will be functionally evaluated in 3 complementary scenarios, related to 3 clinical case-studies: (i) a long stump transradial amputee, (ii) a short stump transradial amputee and (iii) a bilateral transradial amputee. The overall concept underpinning the project is shown in Fig. 2. The 3 scenarios share the same modular design and are composed of six main blocks in order to handle parallel streams of efferent (control signals – dependent on user’s intent) and afferent (sensory feedback signals – based on artificial senses in the prostheses) information. Starting from the human body the six blocks are: (1) the implanted electrodes, (2) the OHMG-TR, (3) the recording/stimulation electronics, (4) the processing and communication nodes, (5) the mechatronic coupler and (6) the hand/wrist prosthesis with proprioception and tactile sensors. Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far During the second reporting period the project has contributed to set up the following activities: • Design and development of the Sensorized Hand Prosthesis (SHP) with embedded sensors (Fig. 3); • Design and development of the wrist for long and short stump scenarios; • Development and test of a novel attachment device that preserves natural forearm rotation while providing a connection that is mechanically and electrically satisfactory; • Design and development of the OHMG-TR and related surgical instruments; • Collect databases of iEMG, HD-sEMG and eEMG signals; • Development of different machine learning algorithms that allow dexterous control of the prosthetic devices; • Advancement of the understanding of human tactile sensation by studying human tactile receptor response to complex tactile stimuli, or during active tactile exploration (Fig. 4); • Exploitation of non-invasive stimulation studies to unveil basic principles that can be used with neural stimulation as well; • Development of a portable neural stimulator that can be integrated in the hand prosthesis; • Design and development of the Miniature Processing and Communication node; • Definition, design and implementation of a high throughput time-constrained RF protocol; • Integration of the alpha prosthesis for the first clinical implant (Fig. 5); • Run preliminary tests with patients treated with OPRA or OHMG (Fig. 6); • Dissemination of the project on several national and international media channels and conferences (Fig. 7); • Identification of foreseen exploitable outcomes. In support to the previous activities we: • published 11 scientific papers on international journals; • gave 26 presentations at international conferences; • gave 15 invited presentations. Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far) The results from this project would impact not only for offering a new solution to people suffering from limb amputation, but also to those having disabling motor deficits due to other neurological diseases (stroke, brain and spinal cord trauma, brachial or lumbosacral plexus and peripheral nerve injuries etc.) which presently affect millions of patients in European countries. More in particular, the objectives of the project are very important: - for social and clinical implications because it is calculated that about 2000 hand amputations occur every year in Europe. - for the biomedical industry because the final results could be exploited by new or existing companies manufacturing limb prostheses, implantable technologies, biomedical instruments and in general assistive technologies. - for neuroscience because by increasing the basic understanding on the way the nervous system dispatches the commands to control the hand to grasp objects, and on the way the cutaneous sensors convey sensory information to the brain, will provide a unique opportunity to learn about the sensorimotor control of limb function. - for cognitive neuroscience because the understanding on the way our brain internalize new afferent channels, and perceives external devices as “own” is important for all (external) prostheses. - for upper limb occupational therapy, because the assessment of the prosthesis by patients, will help understanding the effective power of traditional tests, and lead towards the development of new ones. - for consumer electronics, because the network of processing/communication nodes finds a broad range of application scenarios into mainstream markets like healthcare, consumer electronics, domotics, computer gaming, etc. - for surgery procedures, because the bone-anchoring (osseointegration) implants, surgical methods and procedures will benefit from the lessons learned for implanting the novel OHMG-TR.
- From https://www.brighthubpm.com/six-sigma/84858-three-sigma-vs-six-sigma/:
- 1 Sigma: 690K errors per million (31% accuracy).
- 2 Sigma: 308K errors per million (69% accuracy).
- 3 Sigma: 66.8K errors per million (93.3% accuracy).
- 4 Sigma: 6.2K errors per million (99.4% accuracy).
- 5 Sigma: 233 errors per million (99.97% accuracy).
- 6 Sigma: 3.4 errors per million (99.999997% accuracy)
- This study does examine some anatomical aspect of a transradial osseointegrated amputee but no listed issues were studied. Abstract: Osseointegrated transradial prostheses have the potential to preserve the natural range of wrist rotation, which improves the performance of activities of daily living and reduces compensatory movements that potentially lead to secondary health problems over time. This is possible by enabling the radius and the ulna bone to move with respect to each other, restoring the functionality of the original distal-radioulnar joint. In this paper, we report on psychophysics tests performed on an osseointegrated transradial amputee with the aim to understand the extent of mobility of the implants that is required to preserve the natural forearm rotation. Based on these experiments, we designed and developed an attachment device between the implants and the hand prosthesis that serves as an artificial distal radio-ulnar joint. This device was fitted on an osseointegrated transradial amputee and its functionality assessed by means of the Southampton Hand Assessment Procedure (SHAP) and the Minnesota Manual Dexterity test (MMDT). We found that the axial rotation of the implants is required to preserve forearm rotation, to distribute loads equally over the two implants (60% radius - 40% ulna), and to enable loading of the implants without unpleasant feelings for the patient. Higher function was recorded when our attachment device enabled forearm rotation: SHAP from 61 to 71, MMDT from 258s to 231s. Natural forearm rotation can be successfully restored in transradial amputees by using osseointegration and our novel mechanical attachment to the hand prosthesis.
- Study examines three transhumeral amputees, so it fails to examine transradial amputees. Abstract: Electrical stimulation of tactile nerve fibers that innervated an amputated hand results in vivid sensations experienced at a specific location on the phantom hand, a phenomenon that can be leveraged to convey tactile feedback through bionic hands. Ideally, electrically evoked sensations would be experienced on the appropriate part of the hand: touch with the bionic index fingertip, for example, would elicit a sensation experienced on the index fingertip. However, the perceived locations of sensations are determined by the idiosyncratic position of the stimulating electrode in the nerve and thus are difficult to predict or control. This problem could be circumvented if perceived sensations shifted over time to become consistent with the position of the sensor that triggers them. We show that, after long-term use of a neuromusculoskeletal prosthesis that featured a mismatch between the sensor location and the resulting tactile experience, the perceived location of the touch did not change.
- Study examines three transhumeral amputees, so fails to address transradial issues. Abstract: People with limb loss are for the first time living chronically and uninterruptedly with intimately integrated neuromusculoskeletal prostheses. This new generation of artificial limbs are fixated to the skeleton and operated by bidirectionally transferred neural information. This unprecedented level of human–machine integration is bound to have profound psychosocial effects on the individuals living with these prostheses. Here, we examined the psychosociological impact on people as they integrate neuromusculoskeletal prostheses into their bodies and lives. Three people with transhumeral amputations participated in this study, all of whom had been living with neuromusculoskeletal prostheses in their daily lives between 2 and 6 years at the time of the interview. Direct neural sensory feedback had been enabled for 6 months to 2 years. Participants were interviewed about their experiences living with the neuromusculoskeletal prostheses in their home and professional daily lives. We analyzed these interviews to elucidate themes using an interpretive phenomenological approach that regards participants’ own experiences as forms of expertise and knowledge-making. Our participant-generated results indicate that people adapted and integrated the technology into functional and social arenas of daily living, with positive psychosocial effects on self-esteem, self-image, and social relations intimately linked to improved trust of the prostheses. Participants expressed enhanced prosthetic function, increased and more diverse prosthesis use in tasks of daily living, and improved relationships between their prosthesis and phantom limb. Our interviews with patients also generated critiques of the language commonly used to describe human-prosthetic relations, including terms such as “embodiment,” and the need for specificity surrounding the term “natural” with regard to control versus sensory feedback. Experiences living with neuromusculoskeletal prostheses were complex and subject-dependent, and therefore future research should consider human–machine interaction as a relationship that is constantly enacted, negotiated, and deeply contextualized.
- Nice study regarding four transhumeral amputees, fails also to address transradial amputation entirely. Abstract: We report the use of a bone-anchored, self-contained robotic arm with both sensory and motor components over 3 to 7 years in four patients after transhumeral amputation. The implant allowed for bidirectional communication between a prosthetic hand and electrodes implanted in the nerves and muscles of the upper arm and was anchored to the humerus through osseointegration, the process in which bone cells attach to an artificial surface without formation of fibrous tissue. Use of the device did not require formal training and depended on the intuitive intent of the user to activate movement and sensory feedback from the prosthesis. Daily use resulted in increasing sensory acuity and effectiveness in work and other activities of daily life. (Funded by the Promobilia Foundation and others.)
- Study of three transhumeral amputees, not transradial - mission failed therefore. Abstract: Conventional prosthetic arms suffer from poor controllability and lack of sensory feedback. Owing to the absence of tactile sensory information, prosthetic users must rely on incidental visual and auditory cues. In this study, we investigated the effect of providing tactile perception on motor coordination during routine grasping and grasping under uncertainty. Three transhumeral amputees were implanted with an osseointegrated percutaneous implant system for direct skeletal attachment and bidirectional communication with implanted neuromuscular electrodes. This neuromusculoskeletal prosthesis is a novel concept of artificial limb replacement that allows to extract control signals from electrodes implanted on viable muscle tissue, and to stimulate severed afferent nerve fibers to provide somatosensory feedback. Subjects received tactile feedback using three biologically inspired stimulation paradigms while performing a pick and lift test. The grasped object was instrumented to record grasping and lifting forces and its weight was either constant or unexpectedly changed in between trials. The results were also compared to the no-feedback control condition. Our findings confirm, in line with the neuroscientific literature, that somatosensory feedback is necessary for motor coordination during grasping. Our results also indicate that feedback is more relevant under uncertainty, and its effectiveness can be influenced by the selected neuromodulation paradigm and arguably also the prior experience of the prosthesis user.
- They studied 24 "healthy" participants. No transradial issues examined. Abstract: Background Human sensorimotor control of dexterous manipulation relies on afferent sensory signals. Explicit tactile feedback is generally not available to prosthetic hand users, who have to rely on incidental information sources to partly close the control loop, resulting in suboptimal performance and manipulation difficulty. Recent studies on non-invasive supplementary sensory feedback indicated that time-discrete vibrational feedback delivered upon relevant mechanical events outperforms continuous tactile feedback. However, we hypothesize that continuous tactile feedback can be more effective in non-routine manipulation tasks (i.e., tasks where the grip force is modified reactively in response to the sensory feedback due to the unpredictable behavior of the manipulated object, such as picking and holding a virtual fragile object) if delivered to highly sensitive areas. We further hypothesize that this continuous tactile feedback is not necessary during all the duration of the manipulation task, since adaptation occurs. Methods We investigated the effectiveness of continuous tactile feedback in precision manipulation, together with a new sensory feedback policy, where the continuous tactile feedback is gradually removed when the grasp reaches a steady state (namely, transient tactile feedback). We carried out an experiment in a virtual-reality setting with custom tactile feedback devices, which can apply continuous pressure and vibrations, attached to the thumb and index finger. We enrolled 24 healthy participants and instructed them to pick and hold a fragile virtual cube without breaking it. We compared their manipulation performance when using four different sensory feedback methods, i.e., no tactile feedback, discrete vibrations, continuous tactile feedback, and transient tactile feedback. The latter consisted of gradually removing the continuous feedback in the static phase of the grasp. Results Continuous tactile feedback leads to a significantly larger number of successful trials than discrete vibrational cues and no feedback conditions, yet the gradual removal of the continuous feedback yields to comparable outcomes. Moreover, the participants preferred the continuous stimuli over the vibrational cues and the removal in the static phase did not significantly impact their appreciation of the continuous tactile feedback. Conclusions These results advocate for the use of continuous supplementary tactile feedback for fine manipulation control and indicate that it can seamlessly be removed in the static phase of the grasp, possibly due to the mechanism of sensory adaptation. This encourages the development of energy-efficient supplementary feedback devices for prosthetic and telemanipulation applications, where encumbrance and power consumption are burdensome constraints.
- Review paper of animal studies. Nothing with regard to transradial amputee issues. Abstract: Background: Electrical stimulation of peripheral nerves is used in a variety of applications such as restoring motor function in paralyzed limbs, and more recently, as means to provide intuitive sensory feedback in limb prostheses. However, literature on the safety requirements for stimulation is scarce, particularly for chronic applications. Some aspects of nerve interfacing such as the effect of stimulation parameters on electrochemical processes and charge limitations have been reviewed, but often only for applications in the central nervous system. This review focuses on the safety of electrical stimulation of peripheral nerve in humans. Methods: We analyzed early animal studies evaluating damage thresholds, as well as more recent investigations in humans. Safety requirements were divided into two main categories: passive and active safety. We made the distinction between short-term (< 30 days) and chronic (> 30 days) applications, as well as between electrode preservation (biostability) and body tissue healthy survival (harmlessness). In addition, transferability of experimental results between different tissues and species was considered. Results: At present, extraneural electrodes have shown superior long-term stability in comparison to intraneural electrodes. Safety limitations on pulse amplitude (and consequently, charge injection) are dependent on geometrical factors such as electrode placement, size, and proximity to the stimulated fiber. In contrast, other parameters such as stimulation frequency and percentage of effective stimulation time are more generally applicable. Currently, chronic stimulation at frequencies below 30 Hz and percentages of effective stimulation time below 50% is considered safe, but more precise data drawn from large databases are necessary. Unfortunately, stimulation protocols are not systematically documented in the literature, which limits the feasibility of meta-analysis and impedes the generalization of conclusions. We therefore propose a standardized list of parameters necessary to define electrical stimulation and allow future studies to contribute to meta-analyses. Conclusion: The safety of chronic continuous peripheral nerve stimulation at frequencies higher than 30 Hz has yet to be documented. Precise parameter values leading to stimulation-induced depression of neuronal excitability (SIDNE) and neuronal damage, as well as the transition between the two, are still lacking. At present, neural damage mechanisms through electrical stimulation remain obscure. Keywords: Electrical stimulation, Safety, Peripheral nervous system, Nerve stimulation, Implants
- There were 28 "healthy" participants, irrelevant to above listed transradial amputee issues. Abstract: State of the art myoelectric hand prostheses can restore some feedforward motor function to their users, but they cannot yet restore sensory feedback. It has been shown, using psychophysical tests, that multi-modal sensory feedback is readily used in the formation of the users’ representation of the control task in their central nervous system – their internal model. Hence, to fully describe the effect of providing feedback to prosthesis users, not only should functional outcomes be assessed, but so should the internal model. In this study, we compare the complex interactions between two different feedback types, as well as a combination of the two, on the internal model, and the functional performance of naïve participants without limb difference. We show that adding complementary audio biofeedback to visual feedback enables the development of a significantly stronger internal model for controlling a myoelectric hand compared to visual feedback alone, but adding discrete vibrotactile feedback to vision does not. Both types of feedback, however, improved the functional grasping abilities to a similar degree. Contrary to our expectations, when both types of feedback are combined, the discrete vibrotactile feedback seems to dominate the continuous audio feedback. This finding indicates that simply adding sensory information may not necessarily enhance the formation of the internal model in the short term. In fact, it could even degrade it. These results support our argument that assessment of the internal model is crucial to understanding the effects of any type of feedback, although we cannot be sure that the metrics used here describe the internal model exhaustively. Furthermore, all the feedback types tested herein have been proven to provide significant functional benefits to the participants using a myoelectrically controlled robotic hand. This article, therefore, proposes a crucial conceptual and methodological addition to the evaluation of sensory feedback for upper limb prostheses – the internal model – as well as new types of feedback that promise to significantly and considerably improve functional prosthesis control.
- No issues related to transradial installation and use of osseointegrated interface were examined. Abstract Hand movement is controlled by a large number of muscles acting on multiple joints in the hand and forearm. In a forearm amputee the control of a hand prosthesis is traditionally depending on electromyography from the remaining forearm muscles. Technical improvements have made it possible to safely and routinely implant electrodes inside the muscles and record high-quality signals from individual muscles. In this study, we present a database of intramuscular EMG signals recorded with fine-wire electrodes alongside recordings of hand forces in an isometric setup and with the addition of spike-sorted metadata. Six forearm muscles were recorded from twelve able-bodied subjects and nine forearm muscles from two subjects. The fully automated recording protocol, based on command cues, comprised a variety of hand movements, including some requiring slowly increasing/decreasing force. The recorded data can be used to develop and test algorithms for control of a prosthetic hand. Assessment of the signals was done in both quantitative and qualitative manners.
- Nothing for transradial amputees with osseointegrated interfaces but really bad classification data (accuracy values mean up to around 50% ...) - Abstract: We present the SurfacE Electromyographic with hanD kinematicS (SEEDS) database. It contains electromyographic (EMG) signals and hand kinematics recorded from the forearm muscles of 25 nondisabled subjects while performing 13 different movements at normal and slow-paced speeds. EMG signals were recorded with a high-density 126-channel array centered on the extrinsic flexors of the fingers and 8 further electrodes placed on the extrinsic extensor muscles. A data-glove was used to record 18 angles from the joints of the wrist and fingers. The correct synchronisation of the dataglove and the EMG was ascertained and the resulting data were further validated by implementing a simple classification of the movements. These data can be used to test experimental hypotheses regarding EMG and hand kinematics. Our database allows for the extraction of the neural drive as well as performing electrode selection from the high-density EMG signals. Moreover, the hand kinematic signals allow the development of proportional methods of control of the hand in addition to the more traditional movement classification approaches.
- Another study without focus on transradial amputee osseointegration issues, classification results with up to 78,7% correct based on 14 "healthy" subjects is really really bad. - Abstract: In contemporary muscle-computer interfaces for upper limb prosthetics there is often a trade-off between control robustness and range of executable movements. As a very low movement error rate is necessary in practical applications, this often results in a quite severe limitation of controllability; a problem growing ever more salient as the mechanical sophistication of multifunctional myoelectric prostheses continues to improve. A possible remedy for this could come from the use of multi-label machine learning methods, where complex movements can be expressed as the superposition of several simpler movements. Here, we investigate this claim by applying a multi-labeled classification scheme in the form of a deep convolutional neural network (CNN) to high density surface electromyography (HD-sEMG) recordings. We use 16 independent labels to model the movements of the hand and forearm state, representing its major degrees of freedom. By training the neural network on 16 × 8 sEMG image sequences 24 samples long with a sampling rate of 2048 Hz to detect these labels, we achieved a mean exact match rate of 78.7% and a mean Hamming loss of 2.9% across 14 healthy test subjects. With this, we demonstrate the feasibility of highly versatile and responsive sEMG control interfaces without loss of accuracy.
- Three transhumeral subjects - none of transradial amputee issues were studied at all. Abstract: Sensory feedback is crucial for dexterous manipulation and sense of ownership. Electrical stimulation of severed afferent fibers due to an amputation elicits referred sensations in the missing limb. However, these sensations are commonly reported with a concurrent “electric” or “tingling” character (paresthesia). In this paper, we examined the effect of modulating different pulse parameters on the quality of perceived sensations. Three subjects with above-elbow amputation were implanted with cuff electrodes and stimulated with a train of pulses modulated in either amplitude, width, or frequency (“patterned stimulation”). Pulses were shaped using a slower carrier wave or via quasi-random generation. Subjects were asked to evaluate the natural quality of the resulting sensations using a numeric rating scale. We found that the location of the percepts was distally referred and somatotopically congruent, but their quality remained largely perceived as artificial despite employing patterned modulation. Sensations perceived as arising from the missing limb are intuitive and natural with respect to their location and, therefore, useful for functional restoration. However, our results indicate that sensory transformation from paresthesia to natural qualia seems to require more than patterned stimulation
- Three subjects with transhumeral amputation were studied, no transradial cases or specific issues. Abstract: Background Replacement of a lost limb by an artificial substitute is not yet ideal. Resolution and coordination of motor control approximating that of a biological limb could dramatically improve the functionality of prosthetic devices, and thus reduce the gap towards a suitable limb replacement. Methods In this study, we investigated the control resolution and coordination exhibited by subjects with transhumeral amputation who were implanted with epimysial electrodes and an osseointegrated interface that provides bidirectional communication in addition to skeletal attachment (e-OPRA Implant System). We assessed control resolution and coordination in the context of routine and delicate grasping using the Pick and Lift and the Virtual Eggs Tests. Performance when utilizing implanted electrodes was compared with the standard-of-care technology for myoelectric prostheses, namely surface electrodes. Results Results showed that implanted electrodes provide superior controllability over the prosthetic terminal device compared to conventional surface electrodes. Significant improvements were found in the control of the grip force and its reliability during object transfer. However, these improvements failed to increase motor coordination, and surprisingly decreased the temporal correlation between grip and load forces observed with surface electrodes. We found that despite being more functional and reliable, prosthetic control via implanted electrodes still depended highly on visual feedback. Conclusions Our findings indicate that incidental sensory feedback (visual, auditory, and osseoperceptive in this case) is insufficient for restoring natural grasp behavior in amputees, and support the idea that supplemental tactile sensory feedback is needed to learn and maintain the motor tasks internal model, which could ultimately restore natural grasp behavior in subjects using prosthetic hands
- Data policy paper, nothing about transradial amputees whatsoever. Abstract: Recent years have seen a surge of studies in machine learning in health and biomedicine, driven by digitalization of healthcare environments and increasingly accessible computer systems for conducting analyses. Many of us believe that these developments will lead to significant improvements in patient care. Like many academic disciplines, however, progress is hampered by lack of code and data sharing. In bringing together this PLOS ONE collection on machine learning in health and biomedicine, we sought to focus on the importance of reproducibility, making it a requirement, as far as possible, for authors to share data and code alongside their papers.
- No relevant criteria addressed as outlined above, fourteen apparently anatomically intact volunteers were used here. Abstract: Measurement of forces exerted by a human hand while performing common gestures is a highly valuable task for assessment of neurorehabilitation and neurological disorders, but also, for control of movement that could be directly transferred to assistive devices. Even though accurate and selective multi-joint measurement of hand forces is desirable in both clinical and research applications there is no commercially available device able to perform such measurements. Moreover, the custom-made systems used in research commonly impose limitations, such as availability of only single, predefined hand aperture. Furthermore, there is no consensus on design requirements for custom made measurement systems that would enable comparison of results obtained during research or clinical hand function studies. In an attempt to provide a possible solution for a device capable of multi-joint hand forces measurement and disseminate it to the research community, this paper presents the mechanical and electronic design of an instrumented platform for assessment of isometric hand muscles contractions. Some of the key features related to the developed system are: flexibility in placing the hand/fingers, fast and easy hand fitting, adjustability to different lengths, circumferences and postures of the digits, and the possibility to register individual bidirectional forces from the digits and the wrist. The accuracy of isometric force measurements was evaluated in a controlled test with the reference high accuracy force gauge device during which the developed system showed high linearity (R2 = 0.9999). As the more realistic test, the device was evaluated when force was applied to individual sensors but also during the intramuscular electromyography (iEMG) study. The data gathered during the iEMG measurements was thoroughly assessed to obtain three appropriate metrics; the first estimating crosstalk between individual force sensors; the second evaluating agreement between measured forces and forces estimated through iEMG; and the third providing qualitative evaluation of hand force in respect to activations of individual muscle units. The results of these analyses performed on multiple joint forces show agreement with previously published results, but with the difference that in that case, the measurement was performed with a single degree of freedom device.
- Listing of publications self-inflated, this was listed already above. - Review paper of animal studies. Nothing with regard to transradial amputee issues. Abstract: Background: Electrical stimulation of peripheral nerves is used in a variety of applications such as restoring motor function in paralyzed limbs, and more recently, as means to provide intuitive sensory feedback in limb prostheses. However, literature on the safety requirements for stimulation is scarce, particularly for chronic applications. Some aspects of nerve interfacing such as the effect of stimulation parameters on electrochemical processes and charge limitations have been reviewed, but often only for applications in the central nervous system. This review focuses on the safety of electrical stimulation of peripheral nerve in humans. Methods: We analyzed early animal studies evaluating damage thresholds, as well as more recent investigations in humans. Safety requirements were divided into two main categories: passive and active safety. We made the distinction between short-term (< 30 days) and chronic (> 30 days) applications, as well as between electrode preservation (biostability) and body tissue healthy survival (harmlessness). In addition, transferability of experimental results between different tissues and species was considered. Results: At present, extraneural electrodes have shown superior long-term stability in comparison to intraneural electrodes. Safety limitations on pulse amplitude (and consequently, charge injection) are dependent on geometrical factors such as electrode placement, size, and proximity to the stimulated fiber. In contrast, other parameters such as stimulation frequency and percentage of effective stimulation time are more generally applicable. Currently, chronic stimulation at frequencies below 30 Hz and percentages of effective stimulation time below 50% is considered safe, but more precise data drawn from large databases are necessary. Unfortunately, stimulation protocols are not systematically documented in the literature, which limits the feasibility of meta-analysis and impedes the generalization of conclusions. We therefore propose a standardized list of parameters necessary to define electrical stimulation and allow future studies to contribute to meta-analyses. Conclusion: The safety of chronic continuous peripheral nerve stimulation at frequencies higher than 30 Hz has yet to be documented. Precise parameter values leading to stimulation-induced depression of neuronal excitability (SIDNE) and neuronal damage, as well as the transition between the two, are still lacking. At present, neural damage mechanisms through electrical stimulation remain obscure. Keywords: Electrical stimulation, Safety, Peripheral nervous system, Nerve stimulation, Implant
- No examination of transradial amputee issues as outlined above or of transradial amputee subjects. They used ten able-bodied subjects. Abstract: Developing an artificial arm with functions equivalent to those of the human arm is one of the challenging goals of bioengineering. State-of-the-art prostheses lack several degrees of freedom and force the individuals to compensate for them by means of compensatory movements, which often result in residual limb pain and overuse syndromes. Passive wrists may reduce such compensatory actions, nonetheless to date their actual efficacy, associated to conventional myoelectric hands is a matter of debate. We hypothesized that a transradial prosthesiswould allow a simpler operation if its wrist behaved compliant during the reaching and grasping phase, and stiff during the holding and manipulation phase. To assess this, we compared a stiff and a compliant wrist and evaluating the extent of compensatory movements in the trunk and shoulder, with unimpaired subjects wearing orthoses, while performing nine activities of daily living taken from the southampton hand assessment procedure. Our findings show indeed that the optimal compliance for a prosthetic wrist is specific to the phase of the motor task: the compliant wrist outperforms the stiff wrist during the reaching phase, whereas the stiff wrist exhibits more natural movements during the manipulation phase of heavy objects. Hence, this paper invites rehabilitation engineers to develop wrists with switchable compliance.
- Here, 14 "healthy" subjects were studied outside any scope of relevance for the hot issues A, B, C and D listed above. Abstract: Background The loss of an arm presents a substantial challenge for upper limb amputees when performing activities of daily living. Myoelectric prosthetic devices partially replace lost hand functions; however, lack of sensory feedback and strong understanding of the myoelectric control system prevent prosthesis users from interacting with their environment effectively. Although most research in augmented sensory feedback has focused on real-time regulation, sensory feedback is also essential for enabling the development and correction of internal models, which in turn are used for planning movements and reacting to control variability faster than otherwise possible in the presence of sensory delays. Methods Our recent work has demonstrated that audio-augmented feedback can improve both performance and internal model strength for an abstract target acquisition task. Here we use this concept in controlling a robotic hand, which has inherent dynamics and variability, and apply it to a more functional grasp-and-lift task. We assessed internal model strength using psychophysical tests and used an instrumented Virtual Egg to assess performance. Results Results obtained from 14 able-bodied subjects show that a classifier-based controller augmented with audio feedback enabled stronger internal model (p = 0.018) and better performance (p = 0.028) than a controller without this feedback. Conclusions We extended our previous work and accomplished the first steps on a path towards bridging the gap between research and clinical usability of a hand prosthesis. The main goal was to assess whether the ability to decouple internal model strength and motion variability using the continuous audio-augmented feedback extended to real-world use, where the inherent mechanical variability and dynamics in the mechanisms may contribute to a more complicated interplay between internal model formation and motion variability. We concluded that benefits of using audio-augmented feedback for improving internal model strength of myoelectric controllers extend beyond a virtual target acquisition task to include control of a prosthetic hand.
- Irrelevant study with regard to criteria above, ten "healthy" subjects. Abstract: In the case of a hand amputation, the affected can use myoelectric prostheses to substitute the missing limb and regain motor functionality. Unfortunately, these prostheses do not restore sensory feedback, thus users are forced to rely on vision to avoid object slippage. This is cognitively taxing, as it requires continuous attention to the task. Thus, providing functionally effective sensory feedback is pivotal to reduce the occurrence of slip events and reduce the users’ cognitive burden. However, only a few studies investigated which kind of feedback is the most effective for this purpose, mostly using unrealistic experimental scenarios. Here we attempt a more realistic simulation of involuntary hand opening and subsequent recovery of a stable grasp of the slipping object using a robotic hand operated by the subjects through a standard myoelectric control interface. We compared three stimulation modalities (vision, continuous grip force feedback and discrete slip feedback) and found that the discrete feedback allowed subjects to have higher success rates (close to 100%) in terms of objects recovered from slippage, basically requiring no learning. These results suggest that this simple yet effective feedback can be used to reduce grasp failures in prosthetic users, increasing their confidence in the device.
- Irrelevant study with respect to above criteria. Cost of their error rates (accuracies 65.6 to 84,3%, costing the amputee 6 800 USD to 15 000 USD per year in the above-explained dishwasher cost model. --- Abstract: We present a novel computational technique intended for the robust and adaptable control of a multifunctional prosthetic hand using multichannel surface electromyography. The initial processing of the input data was oriented towards extracting relevant time-domain features of the EMG signal. Following the feature calculation, a piecewise modeling of the multidimensional EMG feature dynamics using vector autoregressive models was performed. The next step included the implementation of hierarchical hidden semi-Markov models to capture transitions between piecewise segments of movements and between different movements. Lastly, inversion of the model using an approximate Bayesian inference scheme served as the classifier. The effectiveness of the novel algorithms was assessed versus methods commonly used for real-time classification of EMGs in a prosthesis control application. The obtained results show that using hidden semi-Markov models as the top layer, instead of the hidden Markov models, ranks top in all the relevant metrics among the tested combinations. The choice of the presented methodology for the control of prosthetic hand is also supported by the equal or lower computational complexity required, compared to other algorithms, which enables the implementation on low-power microcontrollers, and the ability to adapt to user preferences of executing individual movements during activities of daily living.
- Irrelevant study with regard to criteria above. Another slate of unimpressive accuracy values. Abstract: The functionality of upper limb prostheses can be improved by intuitive control strategies that use bioelectric signals measured at the stump level. One such strategy is the decoding of motor volition via myoelectric pattern recognition (MPR), which has shown promising results in controlled environments and more recently in clinical practice. Moreover, not much has been reported about daily life implementation and real-time accuracy of these decoding algorithms. This paper introduces an alternative approach in which MPR allows intuitive control of four different grips and open/close in a multifunctional prosthetic hand. We conducted a clinical proof-of-concept in activities of daily life by constructing a self-contained, MPR-controlled, transradial prosthetic system provided with a novel user interface meant to log errors during real-time operation. The system was used for five days by a unilateral dysmelia subject whose hand had never developed, and who nevertheless learned to generate patterns of myoelectric activity, reported as intuitive, for multi-functional prosthetic control. The subject was instructed to manually log errors when they occurred via the user interface mounted on the prosthesis. This allowed the collection of information about prosthesis usage and real-time classification accuracy. The assessment of capacity for myoelectric control test was used to compare the proposed approach to the conventional prosthetic control approach, direct control. Regarding the MPR approach, the subject reported a more intuitive control when selecting the different grips, but also a higher uncertainty during proportional continuous movements. This paper represents an alternative to the conventional use of MPR, and this alternative may be particularly suitable for a certain type of amputee patients. Moreover, it represents a further validation of MPR with dysmelia cases.
- Nice review generally, but does not directly investigate transradial osseointegration. The only actual transradial case cited here is from 2008, so we knew that since then. For the distinct purpose of addressing issues A, B, C and D (above), the authors could have gone ahead and continue research with patients. - Abstract: Bone-anchored limb prostheses allow for the direct transfer of external loads from the prosthesis to the skeleton, eliminating the need for a socket and the associated problems of poor fit, discomfort, and limited range of movement. A percutaneous implant system for direct skeletal attachment of an external limb must provide a long-term, mechanically stable interface to the bone, along with an infection barrier to the external environment. In addition, the mechanical integrity of the implant system and bone must be preserved despite constant stresses induced by the limb prosthesis. Three different percutaneous implant systems for direct skeletal attachment of external limb prostheses are currently clinically available and a few others are under investigation in human subjects. These systems employ different strategies and have undergone design changes with a view to fulfilling the aforementioned requirements. This review summarises such strategies and design changes, providing an overview of the biomechanical characteristics of current percutaneous implant systems for direct skeletal attachment of amputation limb prostheses.
- Irrelevant w/r to A-D (as above). - Abstract: Background Limb prosthetics, exoskeletons, and neurorehabilitation devices can be intuitively controlled using myoelectric pattern recognition (MPR) to decode the subject’s intended movement. In conventional MPR, descriptive electromyography (EMG) features representing the intended movement are fed into a classification algorithm. The separability of the different movements in the feature space significantly affects the classification complexity. Classification complexity estimating algorithms (CCEAs) were studied in this work in order to improve feature selection, predict MPR performance, and inform on faulty data acquisition. Methods CCEAs such as nearest neighbor separability (NNS), purity, repeatability index (RI), and separability index (SI) were evaluated based on their correlation with classification accuracy, as well as on their suitability to produce highly performing EMG feature sets. SI was evaluated using Mahalanobis distance, Bhattacharyya distance, Hellinger distance, Kullback–Leibler divergence, and a modified version of Mahalanobis distance. Three commonly used classifiers in MPR were used to compute classification accuracy (linear discriminant analysis (LDA), multi-layer perceptron (MLP), and support vector machine (SVM)). The algorithms and analytic graphical user interfaces produced in this work are freely available in BioPatRec. Results NNS and SI were found to be highly correlated with classification accuracy (correlations up to 0.98 for both algorithms) and capable of yielding highly descriptive feature sets. Additionally, the experiments revealed how the level of correlation between the inputs of the classifiers influences classification accuracy, and emphasizes the classifiers’ sensitivity to such redundancy. Conclusions This study deepens the understanding of the classification complexity in prediction of motor volition based on myoelectric information. It also provides researchers with tools to analyze myoelectric recordings in order to improve classification performance.
- Twelve amputee subjects were studied with regard to issues totally irrelevant to issues A, B, C and D (as above), none of which were transradial amputees. Abstract: Osseoperception is the sensation arising from the mechanical stimulation of a bone-anchored prosthesis. Here we show that not only touch, but also hearing is involved in this phenomenon. Using mechanical vibrations ranging from 0.1 to 6 kHz, we performed four psychophysical measures (perception threshold, sensation discrimination, frequency discrimination and reaction time) on 12 upper and lower limb amputees and found that subjects: consistently reported perceiving a sound when the stimulus was delivered at frequencies equal to or above 400 Hz; were able to discriminate frequency differences between stimuli delivered at high stimulation frequencies (~1500 Hz); improved their reaction time for bimodal stimuli (i.e. when both vibration and sound were perceived). Our results demonstrate that osseoperception is a multisensory perception, which can explain the improved environment perception of bone-anchored prosthesis users. This phenomenon might be exploited in novel prosthetic devices to enhance their control, thus ultimately improving the amputees’ quality of life.
- Irrelevant study; they basically say that a TRS Jaws or TRS Prehensor or even a split hook works. This was known already, they could have just sent me an e-mail. Or watched the Cybathlon 2016 arm race. Abstract: The human hand is a complex integrated system with motor and sensory components that provides individuals with high functionality and elegant behaviour. In direct connection with the brain, the hand is capable of performing countless actions ranging from fine digit manipulation to the handling of heavy objects. However the question of which movements mostly contribute to the manipulation skills of the hand, and thus should be included in prosthetic hands, is yet to be answered. Building from our previous work, and assuming that a hand with independent long fingers allowed performance comparable to a hand with coupled fingers, here we explored the actual contribution of independent fingers while performing activities of daily living using custom-built orthoses. Our findings show that, when an opposable thumb is present, independent long fingers provide a measurable advantage in performing activities of daily living only when precision grasps are involved. In addition, the results suggest that the remarkable grasping skills of the human hand rely more on the independent abduction/adduction of the fingers than on their independent flexion/extension. These findings are of interest to the designers of artificial hands, including biomimetic prostheses and exoskeletons.