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ISPO 2015 - review of relevant abstracts [review]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - ISPO 2015 - review of relevant abstracts [review]; published August 3, 2015, 19:18; URL: https://www.swisswuff.ch/tech/?p=5106.

BibTeX: @MISC{schweitzer_wolf_1571592171, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - ISPO 2015 - review of relevant abstracts [review]}}, month = {August},year = {2015}, url = {https://www.swisswuff.ch/tech/?p=5106}}


Contents

Abstracts ISPO 2015

The ISPO had their annual conference in Lyon.

I took the time to collect and comment on some of their scientific abstracts that pertain to technical right below the elbow amputee issues (what, again, was the name of this website?).

All abstracts and images below are cited from the published source [1].

Regarding new body powered technology

VOVC Body-powered hand with multiple grasp patterns

Jon Sensinger (1) presenting James Lipsey (2) Ashley Thomas (2) University of New Brunswick, Fredericton, New Brunswick, Canada (1) Rehabilitation Institute of Chicago, Chicago, Illinois, USA (2)

Background: Body-powered terminal devices are commonly used due to low weight and cost, ruggedness, and accurate control [1], [2]. In contrast, body-powered hands are rarely used – their benefits are similar to terminal devices, in that they both perform a single grasp, but they have a number of relative weaknesses, including added cosmesis inefficiency 1)The Becker hand manages an adaptive grip, which it had decades before myoelectric hands had that; it is only natural that the Becker hand has seen far more revision or development cycles and as that, it has to be regarded as a milestone in body powered prosthetic hand construction. It is laudable to develop a body powered hand to combat "cosmesis inefficiency". But really, no prosthetic arm contains "efficient" cosmesis. This has been sufficiently established by myself (link) seeing as if both academia and industry conveniently overlook this since centuries. Arm amputees are not stupid though, and so given that one fails anyway, look wise, to appear non-disabled, by wearing a currently available prosthetic arm, the hook is not all that bad after all, because at least it provides unprecedented function in the higher range of physical load (which is where overuse is the operative keyword) as well as providing orthopedic means to approximate better balance and symmetry (not a given either, looking at the current "bionic" attempts to ruin our stumps)(#voightkampff). A prosthetic hand rather than a hook may be great for communicating that one "tries" / "attempts" cosmesis, but I do not think anyone that wears these actually believes that we are truly camouflaged, or, ever will be. Which is a pity really, because you then end up dealing with totally disillusioned amputees like myself, when really, you'd kind wanted us to be all excited, "hey, new research"! and visual obstruction of the object being grasped [3]. We have recently designed a body-powered terminal device that can switch between voluntary-opening (VO) and voluntary-closing (VC) mode. This VOVC device has shown improved performance relative to conventional devices when tested using the SHAP test [4], and the concept has promise to improve the performance of body-powered hands.

Aim: The goal of this project was to develop a VOVC body-powered hand that offered a substantial increase in performance compared with split-hook terminal devices2)Developing a prosthetic hand that actually exceeds the performance characteristics of a split hook? That may be impossible, looking at the current players and the last decades of "research". Usually, researchers (as prosthetists) may not know much, I am afraid to say: the performance of hooks generally (as in: measurable robustness in performing highly repeating physically demanding tasks of, say, a Hosmer work hook) is usually totally underestimated (and, to add to it, the Retro hook may actually be totally unknown). I wear a prosthetic arm for stuff I cannot do with one hand; for true grip performance, check grabbing strong copper cables or hedge cutting as examples.  Usually, researchers (as, even sometimes, prosthetists) totally underestimate the need for really good suspension (#voightkampff). Other than that, a body powered hand appears to be a great piece to wear. Just don't run after hook performance! That is because there are people that come up with seriously hard applications and performance tests you would not even dream of. .

Method:  We redesigned the VOVC mechanism to fit within the palm of the hand, allowing the user to either use voluntary-opening mode or voluntary-closing mode. We also designed a thumb that could be manually positioned in different postures such as chuck-grip, fine-tip, and palm-flat. Perhaps most importantly, we designed the fingers such that they could be individually locked in a fully-flexed state 3)When building a body powered hand with an adaptive grip and extra features, locking fingers in a fully extended state may be the better choice than making a fist. Try typing with a prosthetic hand on a stiff socket, that has flexed fingers and try not hitting the SHIFT and CONTROL keys all the time. Just as an example. When using a "fingers out of the way" precision grip it can be a lot better to have extended fingers III, IV and V. After all you wanted to run your newly developed hand against a hook's performance: I can type (i.e., hard bangs against keyboard, thousands of them daily) with a hook rather well; that type of physical exposure usually risks to damage the prosthetic arm really fast unless it is built for what I myself personally call "actual use" (which again is different from what most researchers and prosthetists think is actual use).without inhibiting the motion of the other fingers. This function was achieved by using springs to individually bias each finger in extension; pulling fingers closed using a series of links connected to each finger; and including a push-lock in each knuckle. This design results in a large number of possible grip patterns.

F49.large

 

Results: We were able to combine all of these features into a small #7 hand design that weighs approximately 470g. This hand can achieve a variety of grasp patterns 4)Cool : ) It is certainly great to have a variety of grasp patterns. However, limiting aspect often then is the glove, and the effect the glove has on reducing rip force. Any word on that? needed to perform activities of daily living.

Discussion & Conclusion: The added functional benefits of this hand compared with a split-hook design may allow it to be adopted by more users than previous hands. The design is rugged and comparable in size and weight to existing hands. In future work we will evaluate the performance of this hand using outcome measures such as SHAP and take-home trials.

References:

[1] K. Berning, S. Cohick, R. Johnson, L. Miler, and J. W. Sensinger, “Comparison of body-powered voluntary opening and voluntary closing prehensor for activities of daily living,” J. Rehabil. Res. Dev., vol. 51, no. 2, pp. 253–262, 2014.

[2] R. F. ff. Weir and J. W. Sensinger, “Design of Artificial Arms and Hands for Prosthetic Applications,” in Biomedical Engineering and Design Handbook, 2nd ed., vol. 2, M. Kutz, Ed. New York: McGraw-Hill, 2009, pp. 537–598.

[3] C. M. Fryer, G. E. Stark, and J. W. Michael, “Body-Powered Components,” in Atlas of Amputations and Limb Deficiencies, 3rd ed., D. G. Smith, J. W. Michael, and J. H. Bowker, Eds. Rosemont, IL: American Academy of Orthopaedic Surgeons, 2004, pp. 131–143.

[4] J. W. Sensinger, J. H. Lipsey, A. Thomas, and K. Turner, “Design and evaluation of a voluntary-opening/voluntary-closing prosthetic terminal device,” J. Rehabil. Res. Dev., vol. In press, 2015.

 

Regarding liners

Appropriate liner technology for low income and post war countries

Abdullah Fatlawi (1) presenting - University of Strathclyde, Glasgow, UK (1)

Background -  The World Health Organization (WHO) estimate that one billion people worldwide experience some form of disability and that the majority are from low to middle income countries.  The demands for prosthetic needs are increasing particularly in war zones. A variety of prosthetics liners are available in the developed world and may offers benefits for the use with prostheses. Such liners are generally expensive and therefore unobtainable in the developing countries.

Aim: The aim of the study is to investigate the need for a custom made silicone liner for prosthetic use in low Income (LICs) or Post War Countries (PWCs), and explore the possibility of fabrication for trans-humeral (TH) level.

Method: A literature review was conducted and the advantages and disadvantages of silicone liners discussed. Design criteria using low cost materials for silicone liner production in LIC/PWCs were presented.  The search strategy was intentionally liberal to select as many potential articles as possible. Terms were individually entered, occasionally excluding previous terms, avoiding duplication. Titles, and where appropriate abstracts, were read to ascertain individual paper contents. A traffic light system was used. Red – ignore. Yellow – considered. Green – include. Mainly studies which included upper limb (UL) prosthetics level of amputation were included in the search. Several databases were searched including: Medline: Embase, Cochrane library, SUPrimo, google news search, compendex, sciencedirect and google scholar.

Results: Results were organised into 2 tables for clarity; ‘previous attempt to produce liners’ and ‘types of silicone’. Table 1 lists previous attempts of liner production. 3 papers were found from literature, two of which considered custom made liners and one technical note on the production of hand prosthesis for partial hand amputation. No of the study concerned manufacture of silicon liners for use for LICs only. Tables are too much to be uploaded on this document

Discussion & Conclusion -  Design criteria were developed to facilitate production of silicone liners in LICs/PWCs and included: affordability; durability; easy of manufacture; easily obtainable materials / equipment; and biocompatibility. A production method was determined. Such liners would minimise material usage while maximising value. Costs will be as low as £4 5)One silicone liner for 4 British Pounds is quite affordable and that constitutes a great result of investigative research : ) Actually, silicone liners are used in agriculture to milks cows, and there, they are also not outrageously priced. Besides, standard prefabricated stock liners such as the ones made by Ossur can have serious side effects as the quality of their fit may be bad. .

Prosthetic liner prescription practices: a survey of prosthetists in North America

Brian Hafner (1) presenting John Cagle (1) Joan Sanders (1) University of Washington, Seattle, WA, USA (1)

Background -  The prosthetic liner serves as an interface between the rigid socket and the delicate soft tissues of the residual limb. As such, selection of an appropriate liner is of critical importance to the health of patients with lower limb amputation. It has been suggested that liner selection is primarily based on intuition, product literature, peer recommendations, and experience.1 However, limited evidence exists to accurately characterize prosthetists’ liner selection practices. Specifically, it is unknown how or why practitioners select specific liners for each individual patient.

Aim -  The goals of this project were to characterize the range of liner products commonly used by prosthetists and to determine how they typically select liner products for individual patients.

Method -  A cross-sectional survey was developed by the investigators to evaluate prosthetists’ liner selection practices. Questions were created to assess respondent characteristics (e.g., age, clinical training, and clinical experience), resources they use to learn about liners, frequency with which they use specific liner products, and features of liners they deem important to the liner selection process. Prosthetists in the US and Canada with at least 1 year of experience managing prosthetic patients were recruited via clinical magazine advertisements, professional meeting flyers, and orthotic and prosthetic listserv postings. The survey was administered online using WebQ open-source software.

Results -  Respondents (n=107) were mostly male (79%), non-Hispanic white (87%), and resided in the United States (89%). Respondents were generally educated at the certificate (38%), bachelors (52%), or masters (11%) level and practiced as a certified prosthetist (43%) or certified prosthetist-orthotist (54%). The large majority of respondents indicated they received information about new liner products directly from manufacturers (94%). Fewer reported receiving information from clinical magazines (60%) or scientific journals (15%). The top 25 liner products routinely used by practitioners varied by manufacturer (Össur=11, WillowWood=7, ALPS=3, Otto Bock=3, medi=1). Prosthetists reported the most important liner properties included durability (91%), comfort (87%) and suspension features (78%). A small proportion (11%) of respondents acknowledged using a single liner product with all of their transtibial patients. A larger portion of prosthetists (86%) said they most often used only a few different products (mean=2.4, median=2) for their patients.

Discussion & Conclusion -  Results of this study indicate that prosthetists generally use only a few different prosthetic liner products for their patients with transtibial amputation, despite the availability of more than 60 unique liners on the market. Reasons for prosthetists’ selection practices are unclear, but may be due to a scarcity of comparable information about commercially available prosthetic liners6)Prosthetists in general may not command a good knowledge about prosthetic components generally. But as to why, this is probably not an obscure riddle: usually, prosthetists have commercial contacts if not affiliations with specific manufacturers and through that, they may never care to examine the wider range that is available, or see a reason to do so. Some may tend to push the customer to select from their very narrow range of products, using conviction, a bit of encouragement, compassion (when the liner causes eczema and the eczema hurts), possibly intimidation. When I had a bad case of congestion eczema, due to Ossur liners, my prosthetist  tried to make custom liners using a really hard type of silicone mixtures with the effect that their liners were either too narrow (ouch) or too wide (arm then fell off) and he did that, open end, for at least 3 months, which was when I started to research the field myself. It was me (and not my prosthetist) that had to come up with a viable alternative for a liner that the prosthetist subsequently ordered for me. They did not know that the product that I then suggested and that subsequently worked for me even existed. You all maybe believe I write all of this out of malice - but that really is not true. Was the industry better, technically, and just about halfway reasonable, I would be a really happy camper. . Objective tools or resources that allow practitioners to compare and contrast desirable liner characteristics may help to facilitate greater variety in product selection and improve health outcomes by matching individual patients with the liner product best suited to their needs.

References

  1. Klute et al., Prosthet Orthot Intl, 2010, 34(2):146-53.

 

Multivariate myoelectric signal acquisition based on conductive silicone

Heiko Glindemann (1) presenting Norman Pfeiffer (1) Bernhard Graimann (1) -  Otto Bock HealthCare GmbH, Duderstadt, Germany (1)

Background:  Advanced myoelectric man-machine interfaces require improved signal acquisition. The few electrodes usually used in conventional upper limb prostheses provide only sufficient information for direct and sequential control. For intuitive, simultaneous and proportional control of multifunctional prostheses, multivariate signals are necessary, which capture more information about the muscle activity in the residual limb. Moreover, such a signal acquisition system should be cost effective. This latter requirement is difficult to attain with conventional EMG electrodes used in prosthetics.

Aim:  In this work, we propose a new, cost effective signal acquisition system for multivariate myoelectric signals based on silicone electrodes. We demonstrate the design of the system and show first evaluation results on able-bodied subjects and amputees.

Method:  To reduce the influence of external artifacts the amplifier is usually integrated into the electrode. Alternatively, guarded shielding can achieve similar results. Shielding has the advantage to separate electrodes and amplification which leads to more cost effective solutions. Therefore, we used a guarded shielding approach in combination with electrodes made of conductive silicone7)"Shielding" some human mounted plastic by wrapping it with "shielding" seems funny though, but then, Otto Bock already surprised me years ago. This seems to extend to the infamous "tin foil hat" discussion: without proper grounding, any "shield" may not act as shielding but more like an antenna. That is also why Farabloc may actually not work as advertised; it may work, but through different means. Thus, we all may not understand phantom pains all that well but Aliens, the Bilderberger and the NSA may record all these signals and actually make sense of them, so use the Farabloc or Otto Bock antenna, speak a prayer, and see what happens next. Who knows. Maybe they can do the impossible, switch your phantom pain off, or, force your prosthetic hand into submission. . These electrodes were embedded in non-conductive silicone in a special design to reduce triboelectric effects and movement artifacts. To evaluate this new signal acquisition system, we conducted a study with four abled body subjects to evaluate EMG signal quality as well as online and offline control performance. We compared our system to conventional EMG electrodes used in prosthetics as well as a system based on gel electrodes. Additionally a clothespin test was performed with an amputee.8)Who knows what the effect of "shielding" is, really. Maybe one could test the actual effect of the shielding separately and just on its own. Any characteristics to be measured regarding to that, with regard to "external artifacts"? Doesn't Otto Bock actually employ Axon bus encoding to achieve just that, or was Axon bus signal encoding more to discourage competitors from making hands to be attached to Otto Bock wrists? Can Otto Bock not use ergotherapy to make their signals work better? (They once recommended that I use ergotherapy to come to terms with their faulty hardware, so recommending that utter nonsense back to them is Ganz Grosses Kino really).

Results: A cuff was made integrating 16 conductive silicone electrodes for able bodied subjects9)Amputee research using able bodied subjects ; ) Ups ; ) That should not be standard practice, particularly not for a "leader" in prosthetic manufacturing such as Otto Bock. My stump muscles are all fatty, and degenerated; getting great signals there can be a bit of a bitch to be honest. But, sure, if in fact you are really building arms for able bodied people, if you get kicks out of that, testing  these makes a lot of sense ; ) But then, what next. made out of standard socket material. First tests with four able-bodied subjects showed a comparable signal quality to conventional, active EMG electrodes. Offline classification using linear discriminant analysis with 5 classes leads to similar accuracies (silicone electrodes: 99,49 ± 2,0 %, active EMG electrodes: 99,27 ± 1,9 %). Online control performance was rated by measure speed and throughput during the fulfillment of tasks in a certain virtual reality. Executed tests showed no relevant differences between silicone and gel electrodes. However, it turned out that silicone electrodes are more prone to electrostatic and movement artifacts than conventional electrodes. This was confirmed during a clothespin relocation test with one amputee to control a multi DOF hand prostheses. The completion time was 20% higher than with conventional electrodes.

Discussion & Conclusion : The results confirmed the potential of conductive silicone to build cost effective10)Do I read "cost effective" in the context of "myoelectric" and "Otto Bock" in one single article? Is that the company that sealed el-absolutely-cheapo-batteries into hard plastic to sell them for a fortune (link)? Is that the company that sold me un-tested calibre-mismatched bolt adapters for an absolute premium (link)?  systems for multivariate, myoelectric signal acquisition. Using guarded shielding the electrodes and signal amplification can be separated while the signal quality is not influenced. However, the work also showed that the silicone is more prone to electrostatic noise and movement artefacts11)Myoelectric arms always leave us with more to be desired, don't they. There are cabling, shielding and data analysis problems, definitely. Just saying: once you are after a definite 100% reliability, cable controlled arms are a lot better. Just because you may not know how to build one that actually shreds and wrecks and works well, does not mean the concept as such is bad! Just because somewhere in this abstract I read "more effective", and felt like the true meaning of that term may not have seen a full appreciation or consideration by anyone there.But just because manufacturers use that term in a seemingly playful way does not mean each and every client does. . Although measures were introduced to reduce those artefacts further improvements are necessary.

Regarding wrist units

Flexible and Static Wrist Units in Upper Limb Prosthesis Users

Corry K. van der Sluis (1,2) presenting Marieke Deijs (1,2) Natascha D.M. Ringeling-van Leusen (4) Raoul M. Bongers (1,3) University of Groningen, Groningen, The Netherlands (1) University Medical Center Groningen, Department of Rehabilitation Medicine, Groningen, The Netherlands (2) University Medical Center Groningen, Center for Human Movement Sciences, Groningen, The Netherlands (3) Revant Rehabilitation Center, Breda, The Netherlands (4)

Background - Wrist movements might be important for upper limb prosthesis users to facilitate activities of daily life (ADL) or to prevent overuse complaints. Prosthesis hands with passive wrist motion capabilities, such as flexion/extension, are on the market, but research on the user’s experiences with flexible wrists is limited.

Aim - To compare flexible and static prosthetic wrists on functionality, user-satisfaction and compensatory movements in the shoulder joint.

Method - Eight transradial amputees using a myo-electric prosthesis tested two passive prosthetic wrists in a cross over design. The Flex-wrist (Otto Bock) and Multi-flex wrist (Motion Control) were used for two weeks in their flexible and static condition, respectively. Measurements were performed 5 times: at baseline and after each two week period. Activity performance was measured using SHAP and Box & Block tests. OPUS informed after functioning with the prosthesis. Satisfaction was assessed using D-QUEST, TAPES and open-ended questions. Shoulder joint angles were measured using Xsens, when executing six ADL tasks. After finishing all measurements a semi-structured interview inquired after advantages and disadvantages of all wrist conditions.

Results - No significant differences were found for SHAP, Box &Blocks or OPUS over the different wrist conditions12)Sure, one may wonder whether a flexible or static wrist is better. Now, I wear a Puppchen wrist. That wrist does what a wrist has to do. Why did we build that thing the way we built it? We don't have research money to smoke off into the blue, like some others here! So, all features required to understand prosthetic wrist units for right below elbow amputees are contained in the Puppchen wrist. That is why it was built that way, and that is exactly why it works so well. It allows for fast release-turn-lock action, fast swap-device action, and it is extremely sturdy for push, pull, torque and withstands also extensive vibration. . D-Quest results revealed better ‘ease in adjusting’ and ‘ease of use’ for flexible wrists. Participants’ satisfaction tended to be in favor of flexible wrists: these allowed a less restricted way of moving, made handling easier, and required less awkward movements. All participants but one indicated that they would choose a prosthesis hand with wrist flexion/extension capabilities if they could purchase a new prosthesis. Clear structure was lacking in the changes in shoulder joint angles between wrist conditions as a measure of compensatory movements. In the ADL tasks ‘lifting object’ and ‘handling cutlery’, the use of a flexible wrist seemed to indicate a smaller range of shoulder angles 13)True, the shoulder motion may be a minute bit better if you use a flexible wrist, but if that is relevant in your view: how exactly. .

Discussion & Conclusion - Patient satisfaction was greater for flexible wrists, which was not reflected in results of objective measurement instruments. These instruments showed comparable functionality for static and flexible wrists. Flexible wrists suggest a decrease of compensatory shoulder movements, which might be important for patients with overuse complaints.

Independent Prosthetic Wrist Rotation for Transradial Myoelectric Prosthesis Users and Assessment of Compensatory Motions

Ali Hussaini (1) presenting Peter Kyberd (1) Institute of Biomedical Engineering - University of New Brunswick, Fredericton, New Brunswick, Canada (1)

Background -  Transradial myoelectric prosthesis users face difficulty positioning the electric hand. Many of these users lose their wrist during an amputation. As a result, they are forced to over rotate their shoulder and perform other body compensation to properly orient the hand for a given task. This puts them at risk for developing repetitive strain injuries 14)Let us connect the dots first here, shall we. Wrist units are not the culprit for overuse or strain. Overuse arises, first of all, on the non-disabled side, and the reason is that the disabled arm under performs. Strain relevant activities are not pouring water from a jar, or, opening a marmalade glass once a day or so. Overuse relevant or strain relevant activities are vacuuming, lifting very heavy items, doing seriously repetitive tasks - which is why performance testing using the SHAP is an oxymoron. Relevant activities are heavy and/or repetitive and forcedly bimanual. That cancels most if not all of the tests offered to this very day, to his very conference, in Lyon 2015. So for a prosthetic arm that "performs", you need "fast" and "sturdy" as grip and suspension descriptors first, then you need "light weight" and "comfort" second. So, why are you building myo arms at all. You need an arm just as the one I optimized for 3 years or so ; ) I know what I am doing, and that was the solution I came up with. I have no research money to waste just as others have, so I had to cut to the chase and provide the correct solution right away. There were driving forces behind what I did, which cannot be said about everyone else here. Only then you have a prosthetic arm that you can actually use to prevent overuse, or as in my instance, relieve the injured "non disabled" arm so it can heal over weeks and months. Overuse from repetition affects shoulder, elbow and wrist of the "non disabled" side. That is what one is after first. Postural issues affect both sides, the disabled side a bit more maybe, and may require the weight distribution to be correct. Again, why were you building myo arms? The overall postural approach needs to be consciously guided (after all, I am not the victim of the prosthetic arm) so I will sit straight, stretch and so on.  Then, overuse is mostly a real problem in extremity muscles; postural issues are more contractions but trunk muscles can be trained endlessly, and endless training of trunk muscles is very important. Furthermore, wrist and terminal device together define the degree of postural fit for any given concise situation, so why not considering a hook? Last but not the least, wrist rotation is relevant to attain a grip generally, so driving and holding on to a steering wheel is not just an overuse problem - it is really a "correct angle" problem before anything else. Look, just try to understand a really well built body powered hook before going any further. There are just some truly relevant things that these arms get right.  . Prosthetic wrist units exist but their utility is limited by the lack of independent control from the user15)"Prosthetic wrist units exist but their utility is limited by the lack of independent control from the user"? Nah, my prosthetic wrist has absolutely no restriction in amount or speed that I can rotate it. I just turn my wrist, I rotate it. No more independence is needed. to make functional improvements.

Aim: The goal was to investigate new methods of control to augment the available inputs in a standard 2-site myoelectric device. The design of an objective assessment for detecting functional improvement, if any, was also a necessary for evaluation.

Method: The prosthetic socket was redesigned and the user’s residual forearm rotation was used as a new input source to control a wrist rotator. The design is only viable if the user has a certain level of forearm rotation remaining post-amputation. The new input was used along side surface level EMG which is used to drive hand function. This resulted in a solution where the user could control a prosthetic wrist independently of a one degree of freedom prosthetic hand. A timed assessment test involving the grasping and relocation of 3 clothespins16)Using a forearm rotator against "overuse"? I suggest to have your test participant conduct activities that actually generate loads of torque, pull or push, many hard repetitions and transmission of true force. Not "relocate 3 clothespins". I am not even sure a person that gets shoulder and back pain after relocating 3 clothespins should be allowed to any clinical research test, let alone physical work. was used to measure the effect of the new prosthesis on the user’s compensatory motions. Motion capture was used to calculate joint angles.

Results:  The user performed the test with their current prosthesis and with the new prosthesis with wrist rotation. The motions of the trunk, head, and shoulders were analyzed to see if the new design had an effect on body motion. A reduction in several body motions including a reduction in shoulder angles was seen. Overall a more neutral stance resulted during the assessment, as a result of introducing the new degree of freedom of wrist rotation. The wrist rotator did cause the user to take a longer time to complete the assessment, but there was a willingness to use the new wrist output. The user also reported a reduction in pain at the neck and shoulders.

Discussion & Conclusion - The study identified the limitations of current prosthetic interventions 17)You had 1 person play with a wrist and some clothespins until it hurt after relocating 3 of them, and then, "the study identified "the" limitations "of current prosthetic interventions""? There are no other limitations of current prosthetic interventions because "the" limitations have now been identified? and presents a potential solution to improving functional outcomes for the prosthesis user. A reduction in compensatory motions is possible if additional independent control inputs can be obtained from the user. A new assessment procedure is presented as well that can aid in clinical assessment of any new prosthetic intervention.

Regarding cable control

Hydraulic transmission applied to body powered upper limb prostheses, as an alternative to the Bowden cable

Gerwin Smit (1) presenting Maurice A. LeBlanc (2,1) Dick H. Plettenburg (1) Colombia, Delft University of Technology, Delft (1) The Netherlands, Stanford University (retired), Stanford (2)

Background - The operating force an input energy of a Body Powered (BP) upper limb prosthesis should be low, to enable comfortable control of the device by the amputee. The mechanical efficiency of a BP system must be high and therefore internal friction ought to be as low as possible. The Bowden cable used in current BP devices, is a significant source of inefficiency18)Bowden cables as used in prosthetic arms are usually poor installations that do not amount to the actual concept of a Bowden cable mount. Just having a cable wrap and deflecting the cable does not make that a "Bowden" cable. So friction is an issue, but to reduce it and to extend sheath life, one does not need to resort to hydraulics. One needs to understand and implement the "Bowden" concept. . The internal friction of the Bowden cable increases with an increasing bend angle of the cable. A hydraulic transmission could be a more efficient alternative, as its friction is independent of the bend angle in the tubing [1].

Aim: The aim of this study was to measure and compare the mechanical input energy required for a BP system, using either a Bowden cable transmission, or a hydraulic transmission, combined with standard available terminal devices (TD’s).

Method: Two commercially available TD’s were used: a voluntary closing TRS Hook and an Otto Bock VO hand. In the first test both devices were actuated using a Bowden cable (steel cable, Teflon liner) 19)So a Bowden cable was used? Specifics of the cable mount may play a role here. . The cable was bended around a cylinder (diam. 150 mm), at increasing angles (0°, 90°, 180°, 270°, 360°) 20)Absolutely great to have concise testing specs listed, but the real bends occur more around different values than that. I am not sure 180, 270 and 360 degree are needed.  It is a start though. . In the second test a hydraulic transmission was used, with custom-made hydraulic cylinders. (bore x stroke = 7.5 x 55 mm). Forces and displacements were measured, using a mechanical test bench. The applied input work was calculated, together with the hysteresis (workin-workreturend).

Results:

Table 1 shows the input work of the Bowden cable and the hydraulic transmission, for both TD’s, at increasing bending angles of the cable.

T34.large

Input work of both terminal devices, combined with the Bowden cable and the hydraulic transmission, at different cable bending angles.

Discussion & Conclusion:

The testing shows that the efficiency of the cable system decreases as the bend in the cable increases, whereas the efficiency of the hydraulic system remains constant. For the OB Hand the required input energy is lower for angles larger than 90° (e.g. in activities like putting something in your mouth). For the TRS the input energy of the Bowden cable is the lowest for all angles.

References:

1. LeBlanc, M, “Current Evaluation of Hydraulics to Replace the Cable Force Transmission System for Body-Powered Upper-Limb Prostheses”, Assistive Technology, Vol. 2.3, 1990.

Regarding overuse

Repetitive Strain Injury Risk Factors in Upper Limb Amputees

Biden Ed (1) Hill Wendy (1) presenting LeBlanc Shannon (1) Bush Greg (1) Kyberd Peter (1) University of New Brunswick, Fredericton, NB, Canada (1)

Background:  Surprisingly little research has been done regarding repetitive strain injury or its risk factors in upper limb amputees. Jones and Davidson in 1999 report on a survey and case studies targeted at amputees in their hospital in Australia. Up to half of their amputee population had overuse symptoms. Ostlie et al 2011 reported a relatively large study of amputees in Norway and found similar results. The incidence of pain was higher in the amputees than in their normal controls and they speculate that this may lead to overuse syndromes.

Aim: This study examined self reported pain in working age adults within our clinic population and compared those results to an age matched group of normally limbed controls.

Method: Our clinic includes about 140 upper limb amputees. This study included a survey designed to identify activities and characteristics which might be risk factors for Repetitive Strain Injury. We received responses from 33 21)You surveyed overuse in prosthetic arms and got a return rate of 23%, or of 50% of the few adults, that your clinic had listed. That is what these numbers mean. The others did not get the questions or did not care to answer. of 65 working age adults in our clinic and from 40 age matched normally limbed adults. The survey included basic information on gender, height, weight, etc. as well as asking about participation in activities with or without a prosthesis and questions on pain. Results were analysed using MiniTab V17 ™ statistical software. Comparisons were made between the amputee and normally limbed groups to ensure comparability. Amputees were compared with normally limbed for activity and pain, and comparisons were made between pain levels associated with the sound limb of the amputees and the dominant arm of the normally limbed.

Results: The amputee and normally limbed controls were compared as a group and sub grouped by sex. Comparisons of age, height weight, BMI etc. showed the groups to be similar. A high proportion of both groups reported back pain. Normally limbed individuals reported minimal levels of pain in a combined neck/shoulder/ upper arm measure. By comparison 25% of the amputee population 22)So you say that 25% of "the amputee population". Aren't you taking your mouth just a tad bit full here. "The" amputee population (at least, almost 80%) is a group of people you know nothing about. To list percentages instead of counts for collective sizes of below 100 is a bit questionable also. reported more than minimal pain levels. A significant finding is that about 12% of normally limbed reported wrist and hand pain vs 36% for the sound side of the amputees. These are broadly comparable to the results of the study by Osterlie et al. An interesting finding was that 77% of amputees reporting hand and wrist pain were regular texters whereas all of the normally limbed texters had hand and wrist pain.

Discussion & Conclusion : Upper limb amputees exhibit patterns of pain which are different from those of normally limbed individuals and suggest that they may be at risk of developing Repetitive Strain Injuries in their sound hands. Current activities such as texting may contribute to these risks.23)Texting regularly on a cell phone is the proposed reason that 25.4 out of 33 (how on earth did you arrive at 25.4) arm amputees have overuse problems, which you regard as "a lot" compared to 40/40 non-amputees - which is a "conclusion" you reached without any deeper activity analysis, prosthetic fit analyis or any other type of raw thinking? That the group of folks you advise to wear myo "bionic" arms, too? That how things getting better, hm? Isn't it that the relative risk of arm amputees may be actually lower compared to two handed people to suffer overuse in context of texting, given your data as evidence? 

References :

- Jones, L.E., Davidson, J.H., “Save that arm: A study of problems in the remaining arm of unilateral upper limb amputees”, Prosthetics and Orthotics International, 1999, Vol. 23, No. 1, Pages 55-58

- Østlie, K, Franklin, R, Skjeldal, O., Skrondal, A., Magnus, P., “Musculoskeletal Pain and Overuse Syndromes in Adult Acquired Major Upper-Limb Amputees”, Archives of Physical Medicine and Rehabilitation, Volume 92, Issue 12, December 2011, Pages 1967–1973.e1

Regarding user surveys and satisfaction

Satisfaction of upper limb amputees with their prostheses

Maja Mlakar (1) presenting Helena Burger (1) University rehabilitation Institute, Ljubljana, Slovenia (1)

Background -  Experiences of rehabilitation team for persons with upper limb amputations shows that satisfaction of the patients with their prostheses varied from the very high level of satisfaction to zero. We didn’t find the validate questionnaire which the patients can fill in quickly and we can use them in our every day practice.

Aim: The aim of our study was to find out the opinions of persons who wear upper limb prosthesis about appearance, comfort of socket, durability, function, donning and doffing, ability for daily activities, weight of prosthesis and the feeling of temperature in the socket.

Method: We prepared the questionnaire on the basis of two articles [1,2]. In the study were included all upper limb amputees who visited our outpatient clinic between August 2007 and February 2008 and were active users and willing to participate. The questionnaire had questions about appearance, comfort of socket, durability of prosthesis, function, donning and doffing, ability for daily activities, weight of prosthesis and the feeling of temperature in the socket with four possible answers: bad, satisfying, good and excellent.

Results: In the study were included 19 persons, 5 women and 14 men. They were 50 years old on average (from 20 to 84). Mostly they use cosmetic prosthesis. In the group of persons with cosmetic prosthesis majority of them assess as “good”: appearance, comfort of socket, durability, donning and doffing and the weight of their prostheses. Mark “bad” half of them gave to functionality, ability for daily activities and the feeling of temperature in the socket. Persons with body-powered prosthesis were more satisfied with appearance and donning/doffing of their prostheses while the temperature of the socket was assessed as “bad”. All other factors in this group were assessed mostly as “satisfying”.

Discussion & Conclusion -  There are no many studies about satisfaction of upper limb amputees with their prostheses. Davidson [1] reported that 55% respondents express greatest dissatisfaction with sweating what we can compare with 68% of persons in our study which asses feeling of temperature in the socket as “bad” 24)This does not seem to be a terribly specific experience in relation to prosthetic arms though. About 65% of people wearing protective shoes complain about sweating. It might be important to get a control group for stuff such as that. . Kyberd [3] asked the upper limb amputees about problems with prosthesis. 20% reported about problem with fit, cosmesis 25)Given that NO prosthetic arm ever looks acceptable in that no prosthetic arm available currently efficiently covers up the handicap, having 80% of the users not complain about cosmesis seems to be striking news, as it suggests that look-wise, we could wear a trash bag, a dead octopus or maybe an old rear mirror of a car on the arm stump, and still putter along happily - or wouldn't you think so? Why not consider what that data actually means? and maintenance and 33% reported problem with function. In our study 53% of answer also assesses the function as “bad” or as “satisfying” 26)Good to know the function was either bad or not bad. Great discussion of the results ; ) While we never know what the other 47% figured, given the rest of this analysis here, I assume they were in bed with food poisoning, had left for a field trip or felt that their prosthetic arms "were rabbits" which may not make sense but, hey, survey.  . Upper limb amputees are partially satisfied with their prosthesis 27)Upper limb amputees may be partially satisfied with their prosthesis - true; but, are you partially satisfied with this study? . The questions about topic of satisfaction with upper limb prosthesis have not been fully researched yet.

References

[1] Davidson J. J Hand Ther, 2002,15:62-70.

[2] Alsancak S. Prosthet Orthot Int, 2003, 23:139-145.

[3] Kyberd et al. J Prosthet Orthot, 1998;10(4): 85-95.

Use and satisfaction with adaptive devices in youngsters with upper limb reduction deficiencies

Ecaterina Vasluian (1) Iris Van Wijk (2) presenting Pieter Dijkstra (1) Heleen Reinders-Messelink (3) Corry Van der Sluis (1) University of Groningen, University Medical Center Groningen, Department of Rehabilitation, Groningen, The Netherlands (1) Centre of Excellence for Rehabilitation Medicine Utrecht (De Hoogstraat Rehabilitation and UMC Utrecht), Utrecht, The Netherlands (2) Rehabilitation Friesland, Beetsterzwaag, The Netherlands (3)

Background -  Youngsters with upper limb reduction deficiency (ULRD) may encounter limitations in daily life activities. Prostheses are prescribed to overcome activity limitations, but many are rejected due to discomfort or lack of functionality. Alternative solutions, such as adaptive devices (ADs), may be considered.

Aim: To evaluate the use, satisfaction and social adjustment with ADs compared to prostheses in youngsters with ULRD.

Method: A cross-sectional study using questionnaires was performed. Youngsters with ULRD between 2-20 years old responded to questions about usage of ADs versus prostheses. D-Quest and TAPES were used to evaluate satisfaction and social adjustment, respectively

Results: 360 ADs were used by 76% of 218 participants (n=166). Eighty youngsters used or had used prostheses (37%). Participants were mainly boys (58%) with transversal ULRD (87%). ADs were used in 43% for self-care (using cutlery), mobility (cycling, 28%) or leisure activities (sports, playing musical instruments, 5%). Prostheses were used for mobility (9%), recreation/leisure (6%), work (4%), self-care (4%). The most preferred solution to overcome activity limitations was using own body-parts (>60%), help from others (>50%), using ADs (48%) or prostheses (< 9%). Satisfaction with ADs was higher than with prostheses (P<0.001). Social adjustment with ADs compared to prostheses did not differ.

Discussion & Conclusion -  Youngsters with ULRD used ADs much more than prostheses and were more satisfied with ADs. ADs were mainly used for eating, cycling, sports or playing musical instruments 28)When young people prefer assist devices for what is important in life over prosthetic arms, then that prosthetic arm research should realize that their calling is in assisting people - young and older people all like to eat, cycle, do sports and play music, and in addition, older people have to work ("woyk", "uoark") - all seemingly foreign to prosthetic arm researchers that seem to take it upon themselves to wander off in the direction of single handed tasks such as replacing clothespins or grabbing a cylinder. Actually, it is like talking to a wall when one addresses the reality of prosthetic arm usage: these people. Will. Not. Listen. And this study shows nicely that the fun is where the fun is, and when prosthetic arms impede they are not preferred and that. Is. The. End. Of. It. I am confident this very important study will go unnoticed by the vast array of prosthetic arm "researchers" that will continue to add sensory feedback, more weight and motors and other stuff that has not helped sports, cycling, music playing or hard bimanual work tasks - which is, as we all know by now, what one really would have needed that prosthetic arm for. . Social adjustment with ADs or prostheses was comparable. ADs should be included in standard rehabilitation treatment of youngsters with ULRD.

References:

Adaptive devices in youngsters with upper limb reduction deficiencies : use and satisfaction. Ecaterina Vasluian, MSc, PhD, Iris van Wijk, MD, PhD, Pieter U Dijkstra, Prof, PhD, Heleen A. Reinders-Messelink, MSc, PhD, Corry K. van der Sluis, Prof, PhD. Journal of Rehabilitation Medicine 2014 ; in press.

Relationship between myoelectric hand mounting and QOL in adult upper limb amputees

Hirotaka Tanaka (1) presenting Keiichi Nakamura (1) Kyohei Kawamura (1) Mina Tomonaga (1) Kanan Yatsuya (1) Masayuki Mizote (2) Mituru Hayashi (2) Yoshiki Matsumoto (2) Chubu Rosai Hospital, Nagoya, Japan (1) Matsumoto Prosthetics & Orthotics Manufacturing CO., LTD, nagoya, Japan (2)

Background: Workers’ compensation insurance has classified myoelectric hands as formal prosthetics since 2013 in Japan. The costs associated with myoelectric hands are substantial. After a patient receives a myoelectric hand, it is economical to determine which patients use the myoelectric hand continuously. In recent years, health-related Quality Of Life (QOL) metrics have been used to evaluate numerous pathologies. SF-36 is the most famous health-related QOL survey and has been used for amputee patients in Japan.

Aim: We assessed the SF36 survey results for patients with myoelectric hands, and examined the relationship scores for each item of the survey as it related to use of the myoelectric hand.

Method:  We included 22 upper limb amputees who had been prescribed myoelectric hands in this study. The status of use (or non-use) of the hand was determined by telephone or face-to-face interview 29)Status of use / non-use of myoelectric hands to be assessed via interview? No, that is not sound science. We all know that personal accounts of heroism, dragon slaying, car racing and Mt. Everest climbing may just be a bit exaggerated and wearing a prosthetic arm also must be assessed by reading log files or entries from electronic access to such a hand, I am afraid - how many open/close moves, read-outs of accelerometers to see whether the hand was used as a hammer, and so son. That is where you will find what the hands have been through (and, more importantly, what not). I know. I also have a myoelectric hand that I am wearing every day for at least 10 hours a day ; ) . We examined health-related QOL metrics, using the SF-36v2 before, and at the end of myoelectric hand training, and again after 6 months, 2 years, and 3 years. The results were calculated based on national standard values and each subscale was converted to a Z-value. Subscales were compared at each survey instance and over the entire study period by two-way analysis of variance. Each subscale was compared by T-test in the use group and the non-use group.

Results: Analysis of variance of the eight subscales showed that before training, Role physical (RP) 40.6 < General health (GH) 54.0 (P <0.001), Social functioning (SF) 44.3 <GH 54.0 (P = 0.028), RP 40.6 < Vitality (VT) 51.5 (P = 0.04). Immediately following training, RP 43.9 <VT 53.8 (P = 0.02), RP 43.9 <GH 57.5 (P <0.001), RP43.9 < Mental health (MH) 54.4 (P = 0.007). Comparing the use group and non-use group before myoelectric hand training, VT value was 54 (use group) vs 46.6 (non-use group) (P = 0.092). Immediately following training, Bodily pain (BP) value was 51.8 (use group) vs 44.1 (non-use group) (P = 0.098), VT value (use group) was 56.0 vs 50.2 (non-use group) (P = 0.149), MH value was 56.6 (use group) vs 49.1 (non-use group) (P = 0.178), and after 6 months the BP value was 50.0 (use group) vs 40.7 (non-use group) (P = 0.057), VT value was 54.8 (use group) vs 44.1 (non-use group) (P = 0.01), MH value was 54.1 (use group) vs 46.5 (non-use group) (P = 0.086).

Discussion & Conclusion: Reviewing the survey results showed that the value of physical and social items tended to be lower before patients had completed myoelectric hand training, but improvement was seen over time. For patients who could not continue use of the myoelectric hand, the value of some of the SF36 items is low. 30)So, there are two groups of people - the happy content active ones that use their hands, and, the other ones that don't. Pity we don't know what causes what and all.

Myoelectric arm prosthesis approach in children at the Japan Hyogo Rehabilitation Center

Yaeko Shibata (1) presenting Ayaka Nakasho (1) Futoshi Mizobe (1) Makiko Okamoto (1) Yu Ando (1) Yuka Mouri (1) Nobuyuki Honda (1) Takaaki Chin (1) Yuichiro Honda (1) Jumpei Oba (2) Akio Nakagawa (2) Haruki Nakamura (1) Hyogo Rehabilitation Center, kobe,Hyogo, Japan (1) Kobe Gakuin University, Kobe,Hyogo, Japan (2)

Background -  In the West, early aggressive training with myoelectric arm prosthesis has been reported to be effective for children that lost an arm due to accident and children with birth defects. This is to enable the children to personally decide whether they want to live using a prosthetic arm in the future. Although the approach in Japan has been inadequate, trials with myoelectric arm prosthesis from infancy were started from 2002 at the Hyogo Prefecture Rehabilitation Center and that approach is still in place.

Aim: To clarify the trend in 50 children who underwent training using myoelectric arm prosthesis at this institution in 2002-2014.To introduce the approach and progress of myoelectric arm prosthesis for children and report the usage features and effectiveness of using myoelectric arm prosthesis in real-life setting by age.

Method:  Fifty children who had lost (amputation) an arm that were examined at the Hyogo Prefecture Central Rehabilitation Hospital and had started training with a myoelectric arm prosthesis in 2002-2014 were the subjects. There were 26 males and 24 females. Eighteen had lost the right arm and 32 the left arm. Cause of the loss was congenital loss of an arm in 49 children and amputation due to trauma in one child. All training was out-patient based and one session was approximately 60 min.

Results: Forty five children continued using myolectric arm prosthesis and 5 discontinued the use. Infants were started from the use of decorative prosthetic arms, then introduced to one-electrode controlled and 3-electrode controlled myoelectric arm prosthesis from 1 year of age and 3 years of age onwards, respectively. Methods of play according to age were introduced focusing on grip training such as opening and closing of the hand, and playing with the use of both hands. Moreover, not only use of the prosthesis at home, but motions of using it in social life such as in the nursery and kindergarten were actively conducted.

Discussion & Conclusion -  By wearing a prosthetic arm and using it in daily life from early stages, children will want to use both hands to accomplish tasks, and will have many opportunities where they can experience enjoyment in playing. Increased desire to opt for a prosthetic arm leads to improvement in the quality of life of the person affected. As the role and methods of use of a prosthetic arm changes as a child grows, continued periodical follow up and approaches are indispensible with myoelectric arm prosthesis for children31)It does take small children to really love a myoelectric arm, just like one then still truly loves Barbie and Ken. Once interpersonal intimacy and water polo become factors in adolescents, the myoelectric arm becomes obsolescent. Once then, overuse and asymmetry take a toll, the prosthetic industry does not care any more. Nor do researchers. Then, a well built body powered arm would be great, but, alas. .

Study of the support system for children using myoelectric arm prosthesis for daily activities-exchange between children and parents

Ayaka Nakasho (1) presenting Yaeko Shibata (1) Jumpei OBA (2) Futoshi Mizobe (1) Takaaki Chin (1) Makiko Okamoto (1) Nobuyuki Honda (1) Yu Ando (1) Yuka Mouri (1) Hyogo Rehabilitation Center, Kobe,Hyogo, Japan (1) Kobe Gakuin University, Kobe,Hyogo, Japan (2)

Background- We have been engaged in the myoelectric arm prosthesis approach for children at the Hyogo Prefecture Rehabilitation Center in Japan since 2002. We have provided support centered on individual training according to the stage of development and life task. Thus, we felt the importance of a platform to interchange findings on how others are engaged with this approach, what methods of use will become possible in the future and so on, for children and their guardians to more actively consider the option of “daily living using a myoelectric arm prosthesis”.

Aim - For children that are undergoing training to operate a myoelectric arm prosthesis experience using the prosthesis to play while interacting with other friends. This is to expand the range of use of the prosthesis, improve operating skill and so on. Moreover, as their friends also know that they use a prosthesis, they can proactively seize the opportunity to use the prosthesis. When the guardians know the correct information, they can exchange opinions amongst each other which is linked to resolution of distress and anxiety. This provides an opportunity to examine their reactions towards their children.

Method: A parent exchange event on a holiday for families of children undergoing training of the myoelectric arm prosthesis at this center was announced. Families that desired to participate in the event where the subjects and the site was this center where the event was held for about 6 hours from morning until the afternoon. The program, which consisted of a short training course, was provided for the children to play using a prosthetic arm and for the guardians to exchange opinions and enrich their knowledge. This event was held in 2013 and 2014.

Results: Participants comprised 24 families in 2013, 20 families in 2014. Children were seen to play actively using a prosthetic arm, wore the prosthetic arm longer than usual (without disliking it), and made friends. Though the guardians could exchange information based on experiences, they gave affirmative opinions regarding daily distress and use of prosthesis in the future.

Discussion & Conclusion -  Exchange events are platforms where children can enjoy using prosthetic arms and guardians can deepen their understanding regarding the use of myoelectric arm prosthesis. In addition to individual training, providing such opportunities will either promote the use of myoelectric arm prosthesis or create opportunities to select such usage. Thus, it is preferable for these participants to form a self-help group where they can be exchanging information while investigating ways of making life easier.

Necessity of parents of children that use myoelectric hand to experience using myoelectric hand

Jumpei OBA (1) presenting Yaeko Shibata (2) Futoshi Mizobe (2) Ayaka Nakasho (2) Takaaki Chin (2) Akio Nakagawa (1) Akito Masuda (3) Yuka Mouri (2) Yu Ando (2) Makiko Okamoto (2) Nobuyuki Honda (2)  Kobe Gakuin university, Kobe,Hyogo, Japan (1) Hyogo Rehabilitaion Center, Kobe,Hyogo, Japan (2) Kinki-Gishi, Kobe,Hyogo, Japan (3)

Background - We are engaged in the myoelectric hand approach for children. To date, approximately 50 children.The approach towards children requires the cooperation and understanding of the parents. We are involved not only in children’s use of a myoelectric hand but also actively engaging parents also. Though parents are involved cooperatively in children’s training with myoelectric hand, to date, parents have hardly experienced using myoelectric hand personally.

Aim: The aim was to investigate the need for parents whose children are being trained with myoelectric hand to experience operating a myoelectric hand.

Method: The subjects were parents of children undergoing training with myoelectric hand. Subjects completed in advance a questionnaire on status of experiencing operating a myoelectric hand by gender and age, feeling towards experience the operation of a myoelectric hand, and attitude towards their child using a myoelectric hand. Next, subjects wore and operated a simulated myoelectric hand. Then, they completed a questionnaire on the ease of operating a myoelectric hand and changes in their attitude from then on towards their child who is using a myoelectric hand.

Results: Twenty seven subjects gave their consent and cooperated in this investigation. Subjects comprised 20 females and 7 males. Mean age was 36±6.97 years. No subject had experienced operating a myoelectric hand and 80% expressed interest in having such experience. After experiencing operating a myoelectric hand, 81% felt it difficult to operate the prosthesis. Feelings of the subjects were ‘I now respect my child’, ‘I will support my child more from now’ and so on. Moreover, 81% responded that attitudes towards children when using a myoelectric hand will change. Details of the attitudes were ‘praise’, ‘I will wait until you can operate it, ‘happily connect the prosthesis to the child’ and so on.32)To have parents (or relatives) of amputees get a true first-hand (broom ting) experience of wearing a prosthetic arm is truly a great research idea. It promotes empathy like nothing else. Thank you for this study!

Discussion & Conclusion-  The parents were interested in experiencing operating a myoelectric hand and from such experience, they could obtain an understanding of the use of a myoelectric hand by their children. In addition, obtaining such understanding towards the use of myoelectric hand will produce good changes in the attitude and feelings of parents towards their children. We think that important is parents have to personally experience operating a myoelectric hand.

Upper limb myoelectric prosthetics: outcomes, reimbursement, and beyond

Bertrand Frossard (1) Lewis Mackay (1) presenting Touch Bionics, Livingston, UK (1)

Background: The lack of evidence showing the efficacy of upper limb prostheses has been highlighted (Biddiss & Chau, 2007; Kyberd & Hill, 2011), as a result, the authors of these studies called for the use of standardised measures to meet this need. The need to provide evidence of efficacy using validated measurement tools is also important due to increasing pressure to justify provision of advanced prostheses (Hill et al, 2009).

Aim: This study aimed to determine the efficacy of the i-limb ultra myoelectric multiarticulating hand, as a prosthetic intervention for upper limb absence, to support the French health authority reimbursement application

Method: The Patient Care Pathway (PCP) is an online questionnaire which gathers responses to standardised measures. Data from the Disability of the Arm Shoulder and Hand (DASH) questionnaire were compared via mean comparison and rank tests for 69 i-limb ultra users at pre and post fitting, to demonstrate change in function and symptoms. All patients using an i-limb who had completed a pre and post assessment were included. The population was found to be representative, and consisted of responses from multiple centres. The population size allowed subgroup analyses. As the data collection is ongoing, the current state of the evidence will be shown in addition to the data presented for the reimbursement request.

Results: Table1 shows pre and post fitting mean scores for subgroups and the full cohort:

–15.44 (Statistic Z= -3.727; p<0.05) for 23 patients that previously used a myoelectric hand (all types) prior to the i-limb ultra.

–18.71 (Statistic Z= -3.203; p<0.05) for 14 patients who previously used a myoelectric hand not developed by Touch Bionics.

–8.83 (Statistic Z= -4.523; p<0.05) for full cohort.

Table 1:

T20.medium

Pre and post DASH previous prosthesis users subgroup descriptive statistics

Discussion & Conclusion -  These results show change in excess of the MDC of the DASH for the whole cohort. The change in mean scores for the subgroups were clinically significant as they were approaching the MCID (Kennedy et al, 2011). The post fitting mean (14.94) for the subgroup of 14 was approaching the normative value for the US population (Kennedy et al, 2011). These results were a statistically significant indication that the i-limb ultra improved the functional outcomes of this cohort. 33)To really assess prosthetic function, have them cut hedges at 37 degrees outside. Do not conduct online assessments which are, in essence, self delusional appraisals.

F65.large

 

References:

[1]Biddiss ; 2007 ; P&O Int. [2]Kyberd ; 2011 ; P&O Int.[3]Hill ; 2009 ; JPO [4]Kennedy ; 2011 ; Institute for Work&Health, Toronto.

Regarding myoelectric arms - errors, malfunction

Wireless EMG detector to minimize a Malfunction of the Myoelectric hand prosthesis

SEHOON PARK (1) presenting BUMKI HONG (1) JINHO SON (1) MUSUNG MUN (1) KOREC, INCHEON, Republic of Korea (1)

Background - The upper-limb amputee has mainly used three types of the prosthesis, such as cosmetic, body-powered, myoelectric hand prosthesis. Myoelectric hand prosthesis is particularly useful because of grasping an object easily and with high torque just as controlling the residual muscles. But, many upper-limb amputees firstly using myoelectric hand prosthesis have trouble in unexpected malfunction, which embarrasses them frequently in daily living. Then, it will hardly be used and the upper-limb amputee will be still uncomfortable in daily living with no-functional cosmetic hand or big-sized body-powered type.

Aim - To improve the quality of life of the upper-limb amputee as using myoelectric hand prosthesis, malfunction minimization of the myoelectric hand prosthesis in grasping is absolutely necessary. Therefore, we will solve this problem as finding main cause of the improper EMG (electromyogram) signal states on the activation of daily living.

Method -  Many malfunctions mainly arise from the improper EMG signal which is caused by inner socket loosely coupled with the residual part of the amputee. It also arise from the interference of the muscle activation. To prevent these malfunction as finding ahead these situation, we developed the wireless EMG detecting system that monitering the EMG states(2 channels) while the amputee activating the muscle on the inner socket. We also suggest 4 meaningful main acivities of daily living, walking, folding hand, stretching upward and downward that are likely to be generating the malfunction. In addition, we classified the main cause of the malfunction and suggest the solution according to the EMG status.

Results - Using the developed wireless EMG detecting system, we monitored the EMG signal of the 8 subjects who are trouble in malfunction on activities of daily living as follows.

F32.large

The improper EMG signal from loosely coupled socket has found on 4 amputees while stretching downward, walking, stretch upward. We take a step as fitting the socket with the residual part. 2 amputees are caused from interference while folding arm. In this case, we found more optimized sensor position which has little interference on activation of the other musle. The rest are solved with proper EMG sensor gain variation while monitoring EMG signal on the 4 main activities. All of them haven’t generated any malfunction in fixed position using the current EMG detecting system that are based wired type because of restricting the boundry of the activity.

Discussion & Conclusion -  On the states of activating of daily living, we can easily found the imporper EMG signal using developed wireless EMG detecting system from the loosely coupled socket and interference of the residual muscle activation. About 75% of malfunction is cause of the suggested 4 activities, walking or jogging, stretching downward and upward, folding. If we consider these facts on the processing the manufacture of the myoelectric hand prosthesis, we absolutely reduce malfunction cases and it will improve the quality of life of the upper-limb amputee34)Even warning the user of such a problem, through display or audio signal, would be very helpful. Indeed, walking or having the arm hang down as well as stretching the elbow or flexing it, is the major cause of real deep shit one encounters with myoelectric arms in terms of loss of control. In my instance, I had days I could not even get the controls off the ground and after 15 minutes of trying, absolutely no function. I usually gave up. .

Assessing the cost of small vs. large errors in myoelectric movement control

Jon Sensinger (1) presenting Adrian Aleman (1,2) Kevin Englehart (1) University of New Brunswick, Fredericton, New Brunswick, Canada (1) University of Guadalajara, Guadalajara, Jalisco, Mexico (2)

Background -  The cost of a mistake influences control. For example, holding a rigid cup slightly too tightly with a terminal device has little cost, whereas holding a rigid cup slightly too loosely results in it falling and breaking [1]. Similarly, most people don’t mind small errors in movement, but as the error gets larger, they quickly care more. Knowing this behavior of how much they care as a function of the size of the error is important knowledge that can help us design better prosthesis controllers that minimize the total cost of a given motion.

Aim: The purpose of this study was to quantify the cost-function of myoelectric movement accuracy.

Method:  Twenty-four able-bodied subjects controlled a 1-D cursor on a computer display using two myoelectric sensors placed on their forearm flexors and extensors. They were instructed to follow a random path presented on the screen. The position of their cursor was presented in 50 ms bursts, and unbeknownst to the subjects, we altered the distribution of the cursor position relative to their actual myoelectric-controlled position. But measuring their compensation to changes in the distribution, we were able to assess the cost-function (e.g., how much they cared about little errors vs. big errors) using a previously published technique [2].

Results: We found that subjects had the same cost function for myoelectric control that has previously been reported for joystick control [2], even though myoelectric control has substantially more noise in it. We also found that the cost function is best represented by an upside down bell-curve. This means that subjects care proportionally more about medium errors than small errors, but that for large errors cost begins to level out and they behave the same no matter how large the error is.

Discussion & Conclusion -  We have been able to accurately quantify the cost-function of myoelectric control for movement-tracking. Knowledge of this cost-function will improve our intuitive understanding of designing controllers. It will also be combined with other recently acquired parameters [3] to form a model of human control of prostheses, which can be used to generate an optimal controller.35)It is good to know that somehow, error and compensation somehow correlate. I do wonder whether you would consider any mid term or long term outcome based on error compensation.

References

[1] K. Körding, “Decision theory: what ‘should’ the nervous system do?,” Science, vol. 318, no. 5850, pp. 606–10, Oct. 2007.

[2] K. P. Körding and D. M. Wolpert, “The loss function of sensorimotor learning.,” Proc. Natl. Acad. Sci. U. S. A., vol. 101, no. 26, pp. 9839–42, Jun. 2004.

[3] R. E. Johnson, K. P. Kording, L. J. Hargrove, and J. W. Sensinger, “Does EMG control lead to distinct motor adaptation?,” Front. Neurosci., vol. 8, no. September, p. 302, Jan. 2014.

Making EMG control more predictable improves performance

Sophie Daigle (1) Reva Johnson (2,3) Jon Sensinger (1,2) presenting - University of New Brunswick, Fredericton, New Brunswick, Canada (1) Northwestern University, Evanston, Illinois, USA (2) Rehabilitation Institute of Chicago, Chicago, Illinois, USA (3)

Background: Many amputees want to rely less on visual feedback [1]. However, attempts to provide alternative feedback sources have not been largely successful [2]. There is another way to think of this problem, however – if control was more predictable, amputees would not have to rely on any feedback 36)It is relevant to know that I do not need feedback once my prosthetic arm is truly reliable. Now: my prosthetic arm is very reliable, and, I have limited sensory feedback. I wear a true extreme usage built body powered arm. I wear, in other words, something you have never hard of, nor, seen. As I use to say: prosthetic researchers and me live on two totally different planets. . Indeed, studies have shown that feedback is not useful in itself for real-time control due to sensory delays, but that it is useful in forming internal models that make control more predictable[3]. We have recently demonstrated that although EMG is a relatively noisy control signal, both able-bodied subjects and amputees do indeed develop internal models that make their control more predictable [4], [5]. It remains unclear, however, if these models actually improve performance.

Aim: The aim of this study was to assess whether the formation of internal models improves the accuracy of EMG-controlled movement. The secondary aim was to see whether the formation of internal models reduces the amount of effort required to accurately control prostheses.

Method: 20 able-bodied subjects controlled a 1 degree-of-freedom computer display using EMG sensors placed on the forearm extensor and flexors. They were asked to track a moving target, and were provided with one of three different visual displays that have been shown to provide varying levels of internal model formation [6].

Results: We found a statistically significant reduction in tracking error when subjects were provided with a visual interface that allowed for the formation of internal models (p<0.01). We also found a significant reduction in muscle effort to achieve this level of accuracy (p<0.01).

Discussion & Conclusion: Our work in this area has shown that 1) people using EMG control do develop internal models, and that 2) these models improve performance. This work provides a framework from which we can move forward in our quest to reduce reliance on visual feedback. Rather than looking at feedback for the sake of feedback, we will now begin to ask the question – which feedback sources most strengthen internal models? Importantly, any feedback source that provides lower-quality redundant information will not strengthen these models [7], so we need to look for feedback that provides additional information that vision is unable to adequately capture. 37)Why not just build a reliable arm?

References:

[1] D. J. Atkins, D. C. Y. Heard, and W. H. Donovan, “Upper- Epidemiologic Overview of lndividuals with Upper - Limb Loss and Their Reported Research Priorities.”

[2] C. Antfolk, M. D’Alonzo, B. Rosén, G. Lundborg, F. Sebelius, and C. Cipriani, “Sensory feedback in upper limb prosthetics.,” Expert Rev. Med. Devices, vol. 10, no. 1, pp. 45–54, Jan. 2013.

[3] P. Cisek, “Internal Models,” Encyclopedia of Neuroscience. 2009.

[4] R. E. Johnson, K. P. Kording, L. J. Hargrove, and J. W. Sensinger, “Does EMG control lead to distinct motor adaptation?,” Front. Neurosci., vol. 8, no. September, p. 302, Jan. 2014.

[5] R. E. Johnson, K. P. Kording, L. J. Hargrove, and J. W. Sensinger, “Similar trial-by-trial error correction behavior across transhumeral amputees and able-bodied subjects,” in IEEE/EMBS Conference on Neural Engineering, 2015, p. submitted.

[6] J. Lobo-Prat, A. Q. L. Keemink, A. H. a Stienen, A. C. Schouten, P. H. Veltink, and B. F. J. M. Koopman, “Evaluation of EMG, force and joystick as control interfaces for active arm supports.,” J. Neuroeng. Rehabil., vol. 11, p. 68, Jan. 2014.

[7] M. O. Ernst and M. S. Banks, “Humans integrate visual and haptic information in a statistically optimal fashion.,” Nature, vol. 415, no. 6870, pp. 429–33, Jan. 2002.

Regarding myoelectric arms: training issues

Does EMG control transfer from a serious game to prosthesis use?

Ludger van Dijk (1,2) presenting Hylke van Dijk (3) Corry van der Sluis (1,2) Raoul Bongers (1,2) University of Groningen, Groningen, The Netherlands (1) University Medical Center Groningen, Groningen, The Netherlands (2) NHL University of Applied Sciences, Leeuwarden, The Netherlands (3)

Background -  State-of-the-art myo-electric prosthetic hands require generating complex EMG signals for appropriate control. However, current prosthetic rehabilitation training does not train prosthesis users to reach such an advanced level of skill. Employing serious games in rehabilitation may offer a way of doing that - allowing for feedback about EMG signal quality tailored to an individual user while also creating an enjoyable and stimulating learning context. However, serious games often also change the task the generated EMG signals are involved in. As research suggests skill learning may be fundamentally based on the task the actions aim to accomplish, the question that needs to be addressed is whether learning to control the EMG signal in a serious game will transfer to prosthesis use in daily life.

Aim: To establish (1) whether the control of EMG signals can be trained through serious gaming, and (2) whether this control transfers to a prosthesis-simulator task.

Method: In an experimental pre-test post-test design we trained 15 able-bodied participants to control a video game (Breakout). The goal of the game was to hit bricks by bouncing a ball using a paddle. Participants controlled the movements of the paddle through the EMG signals of the flexors and extensors of the wrist. Another 15 participants, making up the control group, played a regular Mario computer game. Two tests were conducted: (1) one level of the Breakout game was performed and the accuracy of intercepting the ball and EMG signals were measured, (2) participants grasped objects that varied in size with a prosthesis-simulator. Movement time and hand aperture profile were measured.

Results: Analyses showed strong learning effects within the gaming task – on accuracy as well as on the effectiveness of the generated EMG signals. There was no transfer to the task with the prosthesis-simulator.

Discussion & Conclusion - To employ serious gaming in prosthetic rehabilitation it is required that actions used in prosthetic tasks improve by playing the game. The current research suggests that this is not always the case. The results will be used to provide guidelines for a serious game to train prosthesis use. Training sophistication of EMG signals through serious gaming leads to improvement of in-game performance but transfer to prosthetic control is limited.38)Better to cut your partner's hair, repair and modify, setup and ride your own bikes, or otherwise keep real busy (link).

Intermanual Transfer Effects in Upper-Limb Prosthesis Training: the Influence of Inter-Training Intervals

Sietske Romkema (1) presenting Raoul Bongers (2) Corry van der Sluis (1) University of Groningen, Unitversity Medical Centre Groningen, Department of Rehabilitation, Groningen, The Netherlands (1) University of Groningen, University Medical Center Groningen, Center of Human Movement Sciences, Groningen, The Netherlands (2)

Background: Myo-electric prosthetic training should start within the first month after amputation for the best results. To start training directly after an upper-limb amputation intermanual transfer can be used.1,2 Intermanual transfer implies that motor skills learned at one side of the body, transfer to the other side. This suggests that by practising the unaffected arm, in the period between amputation and prosthetic fitting, the affected arm will also improve. Practising the unaffected arm is possible using a prosthetic simulator, a myo-electric prosthesis that can be attached to a sound arm.

Aim: The aim of this study was to determine the influence of inter-training intervals on the magnitude of the intermanual transfer effects.

Method: A mechanistic, randomized, single blinded pretest-posttest design was used. Sixty-four able-bodied, right-handed participants were randomly assigned to two training groups and two control groups. The training groups performed a training program with a prosthesis simulator. The control groups performed a sham training. One of the training groups and one of the control groups trained on five consecutive days, while the other two groups trained twice a week. To determine the improvement in skills, a test was administered before, immediately after, and at two moments after the training. Training was performed with the ‘unaffected’ arm; tests were performed with the ‘affected’ arm. The outcome measures were the movement time (the time from the beginning of the movement until completion of the task), the duration of hand opening, (the opening of the prosthetic hand during grasping an object), and the force control (the error from the required force during a tracking task).

Results: Intermanual transfer was found in movement times, (F3,180=2.847, P=.039), but not in hand opening or force control. The length of the inter-training interval did not affect the magnitude of intermanual transfer effects.

Discussion & Conclusion - Intermanual transfer effects were present in the movement times after prosthesis training. Different inter-training intervals did not influence these effects. Persons with an upper-limb amputation are advised to use intermanual transfer techniques during the period they are waiting for their prosthesis to be manufactured. Patients can then use a daily training program or a training program with larger inter-training intervals.39)It is simply impossible to train the deep and lasting effect that amputation has on perception and learning of the remaining hand / arm as a non-amputee. We have our brains kick into a mode that y'all brains just do not have. All your research shows is results that apply to non-amputees.

References:

1. ROMKEMA, S., BONGERS, R.M. and VAN DER SLUIS, C.K., 2013. Intermanual transfer in training with an upper-limb myoelectric prosthesis simulator: a mechanistic, randomized, pretest-posttest study. Physical Therapy, 93(1), pp. 22-31.

2.  ROMKEMA, S., BONGERS, R.M. and VAN DER SLUIS, C.K., In pres. Intermanual transfer effects in young children after training a complex skill: A Mechanistic, Pseudo-Randomized, Pretest-Posttest Study. Physical Therapyized, Pretest-Posttest Study. Physical Therapy

Regarding myoelectric arms: adding even more "stuff"

Effects of adding vibrotactile sensory feedback on performance and visual attention during a dual-task assignment using a pseudo-prosthetic hand

Eitan Raveh (1) presenting Sigal Portnoy (1) Tel Aviv University, Tel Aviv, Israel (1)

Background: Despite advancements in prosthetic technology, the level of daily use among upper limb prosthetic users is still low, due to several reasons, among them the lack of sensory feedback [1]. Compensation for missing feedback may result in intensified visual attention during performance of simple daily activities [2]. Adding sensory feedback to upper limb prosthetics may reduce the required visual attention, thereby enabling the user to engage in dual-tasking activities.

Aim: (approx. 30 words) Vibrotactile feedback will improve performance and reduce visual attention during dual-task assignments, in healthy individuals using a pseudo-prosthetic hand for performance of functional tasks.

Methods: 27 subjects (mean age: 24.8) participated in the study. A pseudo-prosthetic hand was mounted on the subjects’ right hand, with EMG electrodes placed on their forearm. Pressure sensors were attached to the artificial fingers, and vibrotactile sensors were put on subjects’ arm. In order to measure visual attention and distraction, an eye-tracking system was set. The dual task was to keep a virtual car on a marked path with their left hand, while a series of functional tasks appeared on the screen, e.g. ”Put the spoon of sugar in the glass”. The operation of the vibrotactile feedback system (ON/OFF) was done in an AB/BA design within the group of subjects.

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Results: We aimed to compare the performance and visual attention with versus without feedback. The outcome measures were both the needed time to complete each of the 5 functional tasks, the percentage of time the car in the virtual game was off track, and the number of times the subjects looked at the hand during the dual task. Using the Wilcoxon signed-rank test for comparison, a significant difference (p>0.05) was found only in 4 cases out of 17 outcome measures, as presented on table 1. While using the Mann-Whitney U test, there was no difference between the groups regarding the AB/BA design.

Discussion & Conclusion: This study was designed for healthy subjects, using a pseudo-prosthesis hand, thus simulating the actual use of a prosthesis in amputees’ population. However, there is of course a profound difference between those populations, both in performance and in the lack of sensory feedback. Further research should focus of using a similar setup for prosthetic users, trying to evaluate possible effects on adding vibrotactile feedback during functional tasks.40)This study was designed for "healthy" subjects? With that, they mean to say, "not arm amputees"? So, in Isreal, an amputee cannot be healthy. Good to know. Great that I live somewhere else! Other than that, wear a hard carbon socket body powered arm for a few months, mow the lawn a few times, ride your bike a bit, and then tell me all about vibro-tactile sensory feedback.

References: 1.Dudkiewicz I, Gabrielov R, Siev-Ner I, Zelig G, Heim M. Evaluation of prosthetic usage in upper limb amputees, Disabil Rehabil, 261:60-63, 2004. 2.Blank A, Okamura AM, Kuchenbecker KJ. Identifying the role of proprioception in upper-limb prosthesis control- Studies on targeted motion. ACM Trans Appl Percept 73, 2010

 

Force Limiting Auto Grasp (FLAG): A User–Initiated Method for Grip Security of Electric Hands and TDs

Harold Sears (1) presenting Edwin Iversen (1) Michael Myers (1) Klaus Biggers (1) Motion Control, Inc., Salt Lake City, Utah, USA (1)

Background: High pinch force electric hands and terminal devices (TDs) are difficult to control by the novice wearer, and with 20-25 lb (88-110 N.) pinch force, can exceed even natural hand pinch forces. New myoelectric TD wearers usually do not have well-developed proportional control, and are very cautious gripping fragile objects using their TD around others, especially children. The goal of this project was to develop a simple, easily enabled force limit technique, so the prosthesis wearer can feel comfortable using their high-force TD, resulting in using their prosthesis more.

Aim: Specifications were:

  • The wearer must be able to turn the feature on/off at will.
  • Pinch force must be easily limited, and maintained.
  •  Auto Grasp, i.e., automatic response to electrode slip or loss of contact with skin, should occur when needed, but not occur accidentally.

The combination of these features is termed Force Limiting Auto Grasp (FLAG).

Method: FLAG is implemented by integrating additional controls within existing electronic circuits (the ProPlus Controller), supplemented with sensors within the driven fingers in the Hand prosthesis, and the Electric Terminal Device (ETD).

The wearer completes the following sequence to utilize the FLAG feature:

  • FLAG is enabled with a Hold-Open command for three continuous seconds. An audible and palpable buzz signals the wearer that the FLAG feature is enabled.
  • The wearer intentionally grips an object – the TD will stop gripping at ~2 lb grip force (9 N). A buzz signals the wearer that the grip force has limited, and the motor turned off.
  • The wearer may pulse the grip force (by a contraction of the “close” muscle) to increase the pinch force by ~2 lb (9 N). Each pulse provides a buzz, for feedback to the wearer.
  • To disable FLAG, the wearer performs a Hold-Open command again, for three sec. A double buzz indicates the feature is turned off.
  • While FLAG is enabled, Auto Grasp will trigger a single additional closing pulse, whenever a very sudden opening signal is created, either by a panic or an electrode slip.

Results -A small scale field trial is providing feedback from actual wearers. A sampling of the total data is shown in Table 1. The data is verifying the kinds of tasks for which the feature is useful to the wearers, how frequently the FLAG is utilized, the ease with which the wearers learn its function, and the problems which may require revision to the design or implementation.

View this table:

T12.large

Discussion & Conclusion -  High pinch force can have its downside. Damage to fragile objects, and potential harm to children discourages prosthesis use especially by new wearers. Force Limiting Auto Grasp (FLAG) is shown to increase confidence and usage

 

Environment aware hand prosthesis: A new paradigm for dexterous control

Marko Markovic (1) presenting Strahinja Dosen (2) Dario Farina (2) Otto Bock HealthCare GmbH, Duderstadt, Germany (1) University Medical Center Göttingen, Dep. of NeuroRehabilitation Engineering, Göttingen, Germany (2)

Background: Controlling multifunctional upper limb prostheses with the conventional myoelectric man-machine interface requires switching between the degrees of freedom in a sequential order, and thus it is cumbersome and slow. We have previously developed a system for semi-autonomous control of upper limb prostheses based on computer vision [1]. Here we advance the concept further by fusing additional sensory information in order to extend the overall system applicability.

Aim: The ultimate goal of this research is to simplify the control of a multiple degree-of-freedom prosthesis by endowing the artificial controller with the ability to sense the external environment and make autonomous decisions such as appropriate wrist rotation or grip selection.

Method: The system comprises: 1) Creative Senz3D camera (Creative Technology Ltd.) mounted on the user’s head, implementing the image acquisition, 2) Michelangelo hand prosthesis with a wrist rotator and two 13E200 dry EMG electrodes (Otto Bock Healthcare), and 3) a single MTx inertial sensor (Xsens Technologies B.V.), placed on the prosthesis wrist, for tracking of the 3D prosthesis orientation. When triggered by the user, the system fuses the data acquired from the head-mounted-camera and inertial sensor in order to automatically identify the optimal prosthesis posture (i.e., preshape and orientation) for the given task. It should be noted that, at any moment in time, the user is still able to employ full myoelectric control (semi-autonomous control).

F73.large

Results: We have evaluated the system in one amputee subject, which was experienced (35 years) and active prosthetic user. After a short introductory session the subject was able to fully understand and employ the presented semi-autonomous control scheme (as depicted in the picture). Additionally, we have designed a custom test to compare the performance of our semi-autonomous to the conventional myoelectric control scheme. The test consisted of 15 grasping trials in which the subject had to employ different hand postures in order to successfully grasp the object. In this test the subject was 40% faster when using the semi-automatic control (on average 6.1±1.7s and 10.5±2s needed to grasp the object in semi-automatic and conventional control scenarios, respectively).

Discussion & Conclusion: We have demonstrated how an artificial controller can be enriched with an additional, non-conventional information source (vision and inertial sensors) and a high level processing (cognitive-like reasoning) to achieve fully automatic control of both prosthesis preshaping and rotation. Therefore, high-level tasks can be accomplished automatically, which decreases the cognitive burden from the user, with the final goal of making grasping a routine, effortless activity 41)Environment-aware prosthetic function sounds like real fun. If I can use it to reliably squirt ketchup on fries one day, hey, why not. Maybe reliably finger through the options of a TV remote control why we are at it. Or do you want to say that your system does not even allow for true couch-potato-ism? .

References:

[1] Markovic, M., et al. (2014). Stereovision and augmented reality for closed-loop control of grasping in hand prostheses. Journal of Neural Engineering, 11(4), 046001.

Regarding myoelectric arms: different control paradigms

Improved dexterity of transradial prostheses by movement context dependent control

Sebastian Amsuess (2) presenting Peter Göbel (2) Michael Russold (2) Oskar Aszmann (3) Dario Farina (4) Bernhard Graimann (1) Otto Bock HealthCare GmbH, Duderstadt, Germany (1) Otto Bock Healthcare Products GmbH, Vienna, Austria (2) Medical University Vienna, Christian Doppler Lab for Restoration of Extremity Function, Vienna, Austria (3) University Medical Center Göttingen, Dep. of NeuroRehabilitation Engineering, Göttingen, Germany (4)

Background: Transradial upper limb amputations constitute severe impairments. In order to alleviate the effects of such trauma, sophisticated multifunctional hand prostheses have been developed. A variety of advanced control strategies, most of them based on surface EMG, have been proposed for suitable control of these devices. These approaches can be categorized into classification and regression techniques. While each of these categories exhibits particular strengths, they also have their drawbacks in certain movement control aspects.

Aim: To develop and evaluate a new algorithm for intuitive, simultaneous and proportional control of multifunctional hand prostheses. This algorithm should combine classification and regression techniques in a context dependent way and thus providing either coarse hand positioning or fine object manipulation.

Method: Surface EMG signals from 8 electrode derivations were recorded in 6 healthy and 2 transradial amputee subjects42)So you refer to amputees as "amputees" but to non-amputees as "healthy"? You are from Duderstadt, Germany, and from Vienna, Austria? They teach that there, hm? That amputees cannot be healthy? Dear Otterbock peoples in Austria and Germany, I must tell you that I am very happy not to live in your countries. Your mindset befuddles me. You sure you are healthy? You sure decades ago is decades ago, or are we discussing left overs? while performing the following (phantom) limb movements: wrist pro/supination, wrist flexion/extension, hand open, tripod pinch, lateral grip, and rest - individual movements only. A linear regression (LR) model was trained on the four wrist movements, allowing for simultaneous and proportional combination of these. Additionally, a proportional classification (PC) method was trained with all 8 classes, allowing for precise single movement actuations. Either LR or PC was selected for each movement based on the distance to the training data.

Results: The subjects were able to complete the box and blocks, clothes-pin relocation, block turn and Southampton hand assessment procedure (SHAP) tests with customized experimental prostheses, controlled by the proposed algorithm. Compared to the control with only PC, able-bodied subjects performed significantly faster in complex tests with the movement context dependent control. In both the clothespin and block turn test, completion times were 30% lower with the proposed control method, but were not significantly different in the (easy) box and block test. Additionally, subjects qualitatively reported greater ease and intuitiveness. Only the amputees performed the SHAP test, scoring 58 and 71 points. For the coarse positioning of the prosthetic hand, subjects exploited the simultaneous and proportional control of the wrist joints. Approximately 25 to 35% of all wrist movements were combined movements, depending on the subject’s experience.

Discussion & Conclusion: We propose to intelligently combine regression and classification approaches for surface EMG signals. This combination facilitated simultaneous, proportional control and fine grained precise movement estimations. The quantitative results obtained from tests with able-bodied and amputee subjects, performing online physical tasks with real prostheses, demonstrated that the proposed system outperformed previous state of the art control in transradial prostheses. The seamless fusion of algorithms enabled prosthetic users to intuitively control a complex hand prosthesis.43)Sound great. Now can we build some wrist and hand parts that are not too long? What about error rates and noise ; )

Comparison of Direct Control and Pattern Recognition Control in Transhumeral TMR Subjects

Todd Kuiken (1,2) presenting Laura Miller (1,2) Kristi Turner (1)  Rehabilitation Institute of Chicago, Chicago, IL, USA (1) Northwestern University, Chicago, IL, USA (2)

Background: Individuals who have had Targeted Muscle Reinnervation (TMR) surgery are able to control a prosthetic elbow and hand simultaneously, without mode-switching. However, for direct control, it can be difficult to isolate four different control signals using thresholds and gains. In pattern recognition control, a controller is trained to recognize the different movements, precluding the need to set gains and thresholds and allowing the possibility of controlling additional degrees of freedom, such as the wrist.

Aim: The goal of this study is to compare function in individuals with transhumeral TMR amputations using a commercially available arm system with either direct control or pattern recognition control.

Method: To date, five subjects with transhumeral amputations and who have had TMR surgery were fit with a commercial elbow system (Boston digital arm), a powered wrist rotator, and a powered terminal device (hook or hand). Subjects controlled this device during separate home trials using direct control or pattern recognition control. Subjects were randomized as to which control method was implemented first and used the device for a minimum of six weeks at home with each control paradigm. Pre- and post-home trial outcome measures included the Box and Blocks, the clothespin relocation task, Jebsen, SHAP, and ACMC (post-trial only). Subjects also completed a survey to provide subjective evaluations of control in each configuration.

Results: Using pattern recognition control, subjects had improved scores on the SHAP with an index of function score average of 30.80 (+19.03) compared to 15.20 (+17.06) when using direct control. They were also able to move three clothespins in a shorter period of time (55.89sec + 37.81) compared to using direct control (106.39sec + 95.72). Subjects moved fewer blocks within one minute when using pattern recognition control (7.10 blocks + 3.76) than when using direct control (8.40 blocks + 5.48). No difference was observed between control systems in the Jebsen total time (max of 120s per task; pattern recognition control 425.68sec + 126.29 vs. direct control 436.54 sec +121.46). All 5 subjects preferred pattern recognition control over the direct control configuration.

Discussion & Conclusion: During activities where there was an advantage to accessing all degrees of freedom quickly (e.g., SHAP and clothespin relocation test) scores improved when subjects used pattern recognition control. Subjects also preferred this configuration over direct control, when they were required to switch between the wrist and hand (or wrist and elbow). However, when only hand and elbow movement was desired (e.g., Box and Blocks), subjects had better scores when using direct control, since inadvertent movements did not elicit unwanted prosthesis movements that compromised function. Five additional subjects will complete this study.

Regarding clinical proficiency testing for prosthetic arms

Preliminary study of the Southampton Hand Assessment Procedure for Children and its reliability

Ecaterina Vasluian (1) presenting Raoul M. Bongers (2) Heleen A. Reinders-Messelink (1,3) Pieter U. Dijkstra (1,4) Corry K. van der Sluis (1)  Department of Rehabilitation Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands (1) University of Groningen, University Medical Center Groningen, Center of Human Movement Sciences, Groningen, The Netherlands (2) Rehabilitation Center ‘Revalidatie Friesland’, Beetsterzwaag, The Netherlands (3) Department of Oral and Maxillofacial Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands (4)

Background - The Southampton Hand Assessment Procedure (SHAP) is currently used in the adult population for evaluating the functionality of injured or prosthetic hands (1). The SHAP provides functional scores for six hand grips (spherical, tripod, power, lateral, extension, and tip) and an overall score. The scores are calculated from the performance times of 26 tasks. The SHAP cannot be used for children because of the relatively large size of the objects used to perform SHAP tasks and unknown clinimetric properties.

Aim: The aims of this study were to adapt the SHAP for use in children (SHAP-C) and to analyze the reliability of the SHAP-C in unimpaired children.

Method: The SHAP-C was adapted based on the SHAP protocol. Some objects were downsized to allow grasping with a pediatric hand or pediatric prosthesis. The timing of tasks was performed by the rater instead of the participant; in case of original SHAP the participant times his/her own performance. Intra- and inter-rater reliability were assessed in 4-6 years old children between with unimpaired hands. The repeatability coefficients (RCs) were calculated. An RC ≤ 75% of the mean SHAP-C task values was considered adequate reliability.

Results:  In total 24 children (13 boys), 5 y/o (sd 0.54) participated. Children were all able to perform SHAP-C tasks. The means of the SHAP-C tasks ranged from 0.8 to 1.2 seconds for abstract objects and from 0.6-19.1 seconds for activities of daily living. The RCs of a single assessor did not exceed 75% in 17/26 SHAP-C tasks, displaying a relatively good intra-rater reliability, whereas the RCs for the inter-rater reliability exceeded 75% in 22/26 SHAP-C tasks, thus displaying poor inter-rater reliability.

Discussion & Conclusion -  In this first study that adjusted the SHAP for pediatric use, we found that all SHAP-C objects and tasks could be performed by children. The intra-rater reliability was better than the inter-rater reliability. Possible factors that may have influenced results are data collection method, variation in children’s motivation and assessors’ reaction time. Although the SHAP-C appears to be a promising instrument, the protocol requires further modifications to provide reliable measurements in children. 44)The SHAP was a weird test for prosthetic arms to begin with. We never know whether it really conforms to testing norms either (link).

References:

Light CM; 2002 Arch Phys Med Rehabil. Establishing a standardized clinical assessment tool of pathologic and prosthetic hand function: Normative data, reliability, and validity.

The Clothespin relocation task as a validated outcome measures for upper limb prostheses

Peter Kyberd (1) presenting Ali Hussani (1) Ghislain Maillet (1) Turkey, Institute of Biomedical Engineering, Fredericton, New Brunswick (1)

Background There are numerous tests of arm function, but few have been adequately validated for upper limb prosthesis users, [1]. This is a step in creating an additional test. The clothespin test [2] allows for good visualisation of compensatory motions and is a simple test that employs the hand, wrist and elbow.45)The clothespin test is supposed to add "validated" testing to prosthetic arms. For people interested in validated testing, that might, one day, perhaps, be interesting as soon as the very specifics of the test are made a minute bit less obscure (they are as obscure as the SHAP specifics at this point) - i.e., are the pins located and to be pinned to a slightly swinging cord at or above shoulder level, hence representing a real clothes hanging scenario; and, are the clothespins first with grip parts down and then to be mounted the reverse, hence necessitating exactly that miraculous within-palm-flip that is so crucial to the real world clothes hanging experience, and if not, why is the real world clothes hanging experience deemed unnecessary for people wearing prosthetic arms by "test inventors" again, again, again and yet again? Why do you not want us to succeed in clothes hanging again? It is not something I ate, that's for sure. It appears that for the purpose of this test, clothes pins mounted in willful arbitrary artificial ways to rails, frames or hard edges where no one ever would hang clothes. That, folks, is totally weird. Why do you conduct tests for stuff no one needs, does, uses and performs? Leave alone, routinely in large repetition counts (as those are the only interesting ones to trouble shoot trunk compensatory movements if at all). Size, make, elasticity, coating, and spring force of  clothespins all would need to be carefully specified as I can tell you for free that the handling of a clothespin, using a substandard grip either with a human but definitely with a non-human hand or gripper, is totally dependent on whether it is a crappy or a real crappy one. So, yeah, figuring all that our may take another "10 years" or maybe 50. Considering the last 50 years, however, is not forbidden - and from that, doesn't it appear that we are more looking for an anomaly?

Aim: To provide data of the unimpaired population for comparison with upper limb prosthesis users, to validate the test for prosthesis users.

Method: The test was administered to unimpaired subjects (including retest sessions). Data from prosthesis users was also taken.

Results: The data is from 50 users (ten test-retest). Times are for three pegs brought down from the vertical rail to the horizontal rail. The data for the able bodied subjects showed narrow range, which was not normally distributed. Prosthesis users were markedly slower, (43 - 80s TH, 14 - 65s TR).

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Discussion & Conclusion The nature of the task ensured there is a maximum speed (hence minimum time), and then the values tail off with decreasing speed, hence the non symmetric from. Prosthesis users are slower, with a far broader distribution of times. Design and validation of a new test can take up to a decade.[3, 4]. This test is part of a program to provide a range of different validated tests for use with prosthetic arms 46)You need to consider the uses for a prosthetic arm if you want to understand them. It does not totally become clear what y'all are trying to fix, too. The academic establishment, for the most part, has given up "fixing" amputees since a rather long time. They still pull research grants under the amputee excuse. Why not declare this type of science "science different to real uses of a prosthetic arm". As an arm amputee, I really would hate to see my tax dollars wasted for cross label usage of "prosthetic arm" and "testing" when really it should better be called "academic laboratory attempts far from any reality (ALAFFAR)", formerly called "Academic research under The Amputee Excuse (ARUTAE)". And that, I conclude, is a very valid and extremely relevant point. .

References

[1] L. A. Miller et al., “Summary and Recommendations of the Academy’s State of the Science Conference on Upper Limb Prosthetic Outcome Measures,” JPO, vol. 21(9), pp. P83-P89, 2009.

[2] A. Simon, B. Lock, and K. Stubblefield, “Patient training for functional use of pattern recognition–controlled prostheses,” J. Prosthet. Orthot., vol. 24, no. 2, pp. 56–64, 2012.

[3] V. Wright, “Prosthetic Outcome Measures for Use With Upper Limb Amputees: A Systematic Review of the Peer-Reviewed Literature, 1970 to 2009,” JPO, 21(9), pp. P3-P63, 2009.

[4] V. Wright, “Measurement of Functional Outcome With Individuals Who Use Upper Extremity Prosthetic Devices: Current and Future Directions,” JPO 18, pp. 46-56, 2006

Regarding general health

Self-report of cognitive concerns in people with lower limb loss

Sara Morgan (1) presenting Valerie Kelly (1) Rana Salem (1) Brian Hafner (1) - University of Washington, Seattle, WA, USA (1)

Background: Loss of a limb has traditionally been viewed as a musculoskeletal condition. However, lower limb loss (LLL) has also been associated with presence of cognitive impairment.1 One limitation to prior studies is that studied participants were primarily persons with comorbid dysvascular conditions (e.g., diabetes) and rarely included persons with amputation from traumatic etiology. As such, differences in CI among people with different etiologies of amputation are unknown. Further, prior research most often assessed cognitive difficulties from the perspective of health care providers, rather than people with LLL themselves.1

Aim: To estimate the prevalence and severity of cognitive concerns in persons with LLL by comparing self-reported cognitive difficulties to normative scores. Presence of cognitive concerns by etiology was also examined to assess the relationship between etiology and cognition.

Method: Adult prosthetic limb users with unilateral LLL from dysvascular or traumatic causes were recruited to participate in a cross-sectional study. Each participant completed a one-time paper or electronic survey that included the NeuroQoL Applied Cognition General Concerns (NeuroQoL AC-GC) instrument.2 NeuroQoL AC-GC is an 8-item survey that measures perceived difficulties with cognitive processes (e.g., memory). NeuroQoL scores were compared to normative sample scores (i.e., a T-Score of 50) using one-sample t-tests. Data were then compared by etiology using t-tests to assess differences between groups. The threshold for significance was set at 0.05.

F40.large

Results: Participants (n=1086) were an average of 55 (SD=13) years old. The majority were male (71%) and had at least a high school education (70%). Over half of the sample had amputation from traumatic causes (55%) and most had an amputation at the transtibial level (65%). On average, participants’ most recent amputation occurred 12 (SD=14) years prior. People with LLL reported significantly more difficulties with cognition than the normative sample (p<0.001). Subgroups defined by age and etiology had significantly different NeuroQoL AC-GC scores from the normative sample (both p<0.001), but not significantly different from each other (p>0.05).

Discussion & Conclusion: Overall, people with LLL report concerns with cognitive function. NeuroQoL AC-GC scores are approximately 0.4 SD lower in people with LLL compared to a normative sample based on the U.S. general population. One-half SD has been demonstrated as an acceptable estimate for meaningful difference across outcome measures.3 Additionally, people with LLL from dysvascular causes report similar difficulties with cognition than do those with amputation from traumatic etiology. This result may indicate that concerns with cognitive function are not solely associated with dysvascular comorbidities, but are common to many people with LLL.47)Well, well, well!

References:

  1. Coffey, L. Disabil & Rehab. 34(23), 1950-64, 2012.
  1. Cella, D. Neurology. 78, 1860-67, 2012.
  1. Norman, G.R. Medical Care. 41(5), 582-92, 2003.
[1] [doi] "Abstract Book," Prosthetics and Orthotics International, vol. 39, iss. 1 suppl, pp. 2-608, 2015.
[Bibtex]
@article{ispo2015abstracts,
title = {Abstract Book},
volume = {39}, 
number = {1 suppl}, 
pages = {2-608}, 
year = {2015}, 
doi = {10.1177/0309364615591101}, 
URL = {http://poi.sagepub.com/content/39/1_suppl/2.short}, 
eprint = {http://poi.sagepub.com/content/39/1_suppl/2.full.pdf+html}, 
journal = {Prosthetics and Orthotics International} 
}

 

Footnotes   [ + ]

1. The Becker hand manages an adaptive grip, which it had decades before myoelectric hands had that; it is only natural that the Becker hand has seen far more revision or development cycles and as that, it has to be regarded as a milestone in body powered prosthetic hand construction. It is laudable to develop a body powered hand to combat "cosmesis inefficiency". But really, no prosthetic arm contains "efficient" cosmesis. This has been sufficiently established by myself (link) seeing as if both academia and industry conveniently overlook this since centuries. Arm amputees are not stupid though, and so given that one fails anyway, look wise, to appear non-disabled, by wearing a currently available prosthetic arm, the hook is not all that bad after all, because at least it provides unprecedented function in the higher range of physical load (which is where overuse is the operative keyword) as well as providing orthopedic means to approximate better balance and symmetry (not a given either, looking at the current "bionic" attempts to ruin our stumps)(#voightkampff). A prosthetic hand rather than a hook may be great for communicating that one "tries" / "attempts" cosmesis, but I do not think anyone that wears these actually believes that we are truly camouflaged, or, ever will be. Which is a pity really, because you then end up dealing with totally disillusioned amputees like myself, when really, you'd kind wanted us to be all excited, "hey, new research"!
2. Developing a prosthetic hand that actually exceeds the performance characteristics of a split hook? That may be impossible, looking at the current players and the last decades of "research". Usually, researchers (as prosthetists) may not know much, I am afraid to say: the performance of hooks generally (as in: measurable robustness in performing highly repeating physically demanding tasks of, say, a Hosmer work hook) is usually totally underestimated (and, to add to it, the Retro hook may actually be totally unknown). I wear a prosthetic arm for stuff I cannot do with one hand; for true grip performance, check grabbing strong copper cables or hedge cutting as examples.  Usually, researchers (as, even sometimes, prosthetists) totally underestimate the need for really good suspension (#voightkampff). Other than that, a body powered hand appears to be a great piece to wear. Just don't run after hook performance! That is because there are people that come up with seriously hard applications and performance tests you would not even dream of.
3. When building a body powered hand with an adaptive grip and extra features, locking fingers in a fully extended state may be the better choice than making a fist. Try typing with a prosthetic hand on a stiff socket, that has flexed fingers and try not hitting the SHIFT and CONTROL keys all the time. Just as an example. When using a "fingers out of the way" precision grip it can be a lot better to have extended fingers III, IV and V. After all you wanted to run your newly developed hand against a hook's performance: I can type (i.e., hard bangs against keyboard, thousands of them daily) with a hook rather well; that type of physical exposure usually risks to damage the prosthetic arm really fast unless it is built for what I myself personally call "actual use" (which again is different from what most researchers and prosthetists think is actual use).
4. Cool : ) It is certainly great to have a variety of grasp patterns. However, limiting aspect often then is the glove, and the effect the glove has on reducing rip force. Any word on that?
5. One silicone liner for 4 British Pounds is quite affordable and that constitutes a great result of investigative research : ) Actually, silicone liners are used in agriculture to milks cows, and there, they are also not outrageously priced. Besides, standard prefabricated stock liners such as the ones made by Ossur can have serious side effects as the quality of their fit may be bad.
6. Prosthetists in general may not command a good knowledge about prosthetic components generally. But as to why, this is probably not an obscure riddle: usually, prosthetists have commercial contacts if not affiliations with specific manufacturers and through that, they may never care to examine the wider range that is available, or see a reason to do so. Some may tend to push the customer to select from their very narrow range of products, using conviction, a bit of encouragement, compassion (when the liner causes eczema and the eczema hurts), possibly intimidation. When I had a bad case of congestion eczema, due to Ossur liners, my prosthetist  tried to make custom liners using a really hard type of silicone mixtures with the effect that their liners were either too narrow (ouch) or too wide (arm then fell off) and he did that, open end, for at least 3 months, which was when I started to research the field myself. It was me (and not my prosthetist) that had to come up with a viable alternative for a liner that the prosthetist subsequently ordered for me. They did not know that the product that I then suggested and that subsequently worked for me even existed. You all maybe believe I write all of this out of malice - but that really is not true. Was the industry better, technically, and just about halfway reasonable, I would be a really happy camper.
7. "Shielding" some human mounted plastic by wrapping it with "shielding" seems funny though, but then, Otto Bock already surprised me years ago. This seems to extend to the infamous "tin foil hat" discussion: without proper grounding, any "shield" may not act as shielding but more like an antenna. That is also why Farabloc may actually not work as advertised; it may work, but through different means. Thus, we all may not understand phantom pains all that well but Aliens, the Bilderberger and the NSA may record all these signals and actually make sense of them, so use the Farabloc or Otto Bock antenna, speak a prayer, and see what happens next. Who knows. Maybe they can do the impossible, switch your phantom pain off, or, force your prosthetic hand into submission.
8. Who knows what the effect of "shielding" is, really. Maybe one could test the actual effect of the shielding separately and just on its own. Any characteristics to be measured regarding to that, with regard to "external artifacts"? Doesn't Otto Bock actually employ Axon bus encoding to achieve just that, or was Axon bus signal encoding more to discourage competitors from making hands to be attached to Otto Bock wrists? Can Otto Bock not use ergotherapy to make their signals work better? (They once recommended that I use ergotherapy to come to terms with their faulty hardware, so recommending that utter nonsense back to them is Ganz Grosses Kino really).
9. Amputee research using able bodied subjects ; ) Ups ; ) That should not be standard practice, particularly not for a "leader" in prosthetic manufacturing such as Otto Bock. My stump muscles are all fatty, and degenerated; getting great signals there can be a bit of a bitch to be honest. But, sure, if in fact you are really building arms for able bodied people, if you get kicks out of that, testing  these makes a lot of sense ; ) But then, what next.
10. Do I read "cost effective" in the context of "myoelectric" and "Otto Bock" in one single article? Is that the company that sealed el-absolutely-cheapo-batteries into hard plastic to sell them for a fortune (link)? Is that the company that sold me un-tested calibre-mismatched bolt adapters for an absolute premium (link)? 
11. Myoelectric arms always leave us with more to be desired, don't they. There are cabling, shielding and data analysis problems, definitely. Just saying: once you are after a definite 100% reliability, cable controlled arms are a lot better. Just because you may not know how to build one that actually shreds and wrecks and works well, does not mean the concept as such is bad! Just because somewhere in this abstract I read "more effective", and felt like the true meaning of that term may not have seen a full appreciation or consideration by anyone there.But just because manufacturers use that term in a seemingly playful way does not mean each and every client does.
12. Sure, one may wonder whether a flexible or static wrist is better. Now, I wear a Puppchen wrist. That wrist does what a wrist has to do. Why did we build that thing the way we built it? We don't have research money to smoke off into the blue, like some others here! So, all features required to understand prosthetic wrist units for right below elbow amputees are contained in the Puppchen wrist. That is why it was built that way, and that is exactly why it works so well. It allows for fast release-turn-lock action, fast swap-device action, and it is extremely sturdy for push, pull, torque and withstands also extensive vibration.
13. True, the shoulder motion may be a minute bit better if you use a flexible wrist, but if that is relevant in your view: how exactly.
14. Let us connect the dots first here, shall we. Wrist units are not the culprit for overuse or strain. Overuse arises, first of all, on the non-disabled side, and the reason is that the disabled arm under performs. Strain relevant activities are not pouring water from a jar, or, opening a marmalade glass once a day or so. Overuse relevant or strain relevant activities are vacuuming, lifting very heavy items, doing seriously repetitive tasks - which is why performance testing using the SHAP is an oxymoron. Relevant activities are heavy and/or repetitive and forcedly bimanual. That cancels most if not all of the tests offered to this very day, to his very conference, in Lyon 2015. So for a prosthetic arm that "performs", you need "fast" and "sturdy" as grip and suspension descriptors first, then you need "light weight" and "comfort" second. So, why are you building myo arms at all. You need an arm just as the one I optimized for 3 years or so ; ) I know what I am doing, and that was the solution I came up with. I have no research money to waste just as others have, so I had to cut to the chase and provide the correct solution right away. There were driving forces behind what I did, which cannot be said about everyone else here. Only then you have a prosthetic arm that you can actually use to prevent overuse, or as in my instance, relieve the injured "non disabled" arm so it can heal over weeks and months. Overuse from repetition affects shoulder, elbow and wrist of the "non disabled" side. That is what one is after first. Postural issues affect both sides, the disabled side a bit more maybe, and may require the weight distribution to be correct. Again, why were you building myo arms? The overall postural approach needs to be consciously guided (after all, I am not the victim of the prosthetic arm) so I will sit straight, stretch and so on.  Then, overuse is mostly a real problem in extremity muscles; postural issues are more contractions but trunk muscles can be trained endlessly, and endless training of trunk muscles is very important. Furthermore, wrist and terminal device together define the degree of postural fit for any given concise situation, so why not considering a hook? Last but not the least, wrist rotation is relevant to attain a grip generally, so driving and holding on to a steering wheel is not just an overuse problem - it is really a "correct angle" problem before anything else. Look, just try to understand a really well built body powered hook before going any further. There are just some truly relevant things that these arms get right. 
15. "Prosthetic wrist units exist but their utility is limited by the lack of independent control from the user"? Nah, my prosthetic wrist has absolutely no restriction in amount or speed that I can rotate it. I just turn my wrist, I rotate it. No more independence is needed.
16. Using a forearm rotator against "overuse"? I suggest to have your test participant conduct activities that actually generate loads of torque, pull or push, many hard repetitions and transmission of true force. Not "relocate 3 clothespins". I am not even sure a person that gets shoulder and back pain after relocating 3 clothespins should be allowed to any clinical research test, let alone physical work.
17. You had 1 person play with a wrist and some clothespins until it hurt after relocating 3 of them, and then, "the study identified "the" limitations "of current prosthetic interventions""? There are no other limitations of current prosthetic interventions because "the" limitations have now been identified?
18. Bowden cables as used in prosthetic arms are usually poor installations that do not amount to the actual concept of a Bowden cable mount. Just having a cable wrap and deflecting the cable does not make that a "Bowden" cable. So friction is an issue, but to reduce it and to extend sheath life, one does not need to resort to hydraulics. One needs to understand and implement the "Bowden" concept.
19. So a Bowden cable was used? Specifics of the cable mount may play a role here.
20. Absolutely great to have concise testing specs listed, but the real bends occur more around different values than that. I am not sure 180, 270 and 360 degree are needed.  It is a start though.
21. You surveyed overuse in prosthetic arms and got a return rate of 23%, or of 50% of the few adults, that your clinic had listed. That is what these numbers mean. The others did not get the questions or did not care to answer.
22. So you say that 25% of "the amputee population". Aren't you taking your mouth just a tad bit full here. "The" amputee population (at least, almost 80%) is a group of people you know nothing about. To list percentages instead of counts for collective sizes of below 100 is a bit questionable also.
23. Texting regularly on a cell phone is the proposed reason that 25.4 out of 33 (how on earth did you arrive at 25.4) arm amputees have overuse problems, which you regard as "a lot" compared to 40/40 non-amputees - which is a "conclusion" you reached without any deeper activity analysis, prosthetic fit analyis or any other type of raw thinking? That the group of folks you advise to wear myo "bionic" arms, too? That how things getting better, hm? Isn't it that the relative risk of arm amputees may be actually lower compared to two handed people to suffer overuse in context of texting, given your data as evidence? 
24. This does not seem to be a terribly specific experience in relation to prosthetic arms though. About 65% of people wearing protective shoes complain about sweating. It might be important to get a control group for stuff such as that.
25. Given that NO prosthetic arm ever looks acceptable in that no prosthetic arm available currently efficiently covers up the handicap, having 80% of the users not complain about cosmesis seems to be striking news, as it suggests that look-wise, we could wear a trash bag, a dead octopus or maybe an old rear mirror of a car on the arm stump, and still putter along happily - or wouldn't you think so? Why not consider what that data actually means?
26. Good to know the function was either bad or not bad. Great discussion of the results ; ) While we never know what the other 47% figured, given the rest of this analysis here, I assume they were in bed with food poisoning, had left for a field trip or felt that their prosthetic arms "were rabbits" which may not make sense but, hey, survey. 
27. Upper limb amputees may be partially satisfied with their prosthesis - true; but, are you partially satisfied with this study?
28. When young people prefer assist devices for what is important in life over prosthetic arms, then that prosthetic arm research should realize that their calling is in assisting people - young and older people all like to eat, cycle, do sports and play music, and in addition, older people have to work ("woyk", "uoark") - all seemingly foreign to prosthetic arm researchers that seem to take it upon themselves to wander off in the direction of single handed tasks such as replacing clothespins or grabbing a cylinder. Actually, it is like talking to a wall when one addresses the reality of prosthetic arm usage: these people. Will. Not. Listen. And this study shows nicely that the fun is where the fun is, and when prosthetic arms impede they are not preferred and that. Is. The. End. Of. It. I am confident this very important study will go unnoticed by the vast array of prosthetic arm "researchers" that will continue to add sensory feedback, more weight and motors and other stuff that has not helped sports, cycling, music playing or hard bimanual work tasks - which is, as we all know by now, what one really would have needed that prosthetic arm for.
29. Status of use / non-use of myoelectric hands to be assessed via interview? No, that is not sound science. We all know that personal accounts of heroism, dragon slaying, car racing and Mt. Everest climbing may just be a bit exaggerated and wearing a prosthetic arm also must be assessed by reading log files or entries from electronic access to such a hand, I am afraid - how many open/close moves, read-outs of accelerometers to see whether the hand was used as a hammer, and so son. That is where you will find what the hands have been through (and, more importantly, what not). I know. I also have a myoelectric hand that I am wearing every day for at least 10 hours a day ; )
30. So, there are two groups of people - the happy content active ones that use their hands, and, the other ones that don't. Pity we don't know what causes what and all.
31. It does take small children to really love a myoelectric arm, just like one then still truly loves Barbie and Ken. Once interpersonal intimacy and water polo become factors in adolescents, the myoelectric arm becomes obsolescent. Once then, overuse and asymmetry take a toll, the prosthetic industry does not care any more. Nor do researchers. Then, a well built body powered arm would be great, but, alas.
32. To have parents (or relatives) of amputees get a true first-hand (broom ting) experience of wearing a prosthetic arm is truly a great research idea. It promotes empathy like nothing else. Thank you for this study!
33. To really assess prosthetic function, have them cut hedges at 37 degrees outside. Do not conduct online assessments which are, in essence, self delusional appraisals.
34. Even warning the user of such a problem, through display or audio signal, would be very helpful. Indeed, walking or having the arm hang down as well as stretching the elbow or flexing it, is the major cause of real deep shit one encounters with myoelectric arms in terms of loss of control. In my instance, I had days I could not even get the controls off the ground and after 15 minutes of trying, absolutely no function. I usually gave up.
35. It is good to know that somehow, error and compensation somehow correlate. I do wonder whether you would consider any mid term or long term outcome based on error compensation.
36. It is relevant to know that I do not need feedback once my prosthetic arm is truly reliable. Now: my prosthetic arm is very reliable, and, I have limited sensory feedback. I wear a true extreme usage built body powered arm. I wear, in other words, something you have never hard of, nor, seen. As I use to say: prosthetic researchers and me live on two totally different planets.
37. Why not just build a reliable arm?
38. Better to cut your partner's hair, repair and modify, setup and ride your own bikes, or otherwise keep real busy (link).
39. It is simply impossible to train the deep and lasting effect that amputation has on perception and learning of the remaining hand / arm as a non-amputee. We have our brains kick into a mode that y'all brains just do not have. All your research shows is results that apply to non-amputees.
40. This study was designed for "healthy" subjects? With that, they mean to say, "not arm amputees"? So, in Isreal, an amputee cannot be healthy. Good to know. Great that I live somewhere else! Other than that, wear a hard carbon socket body powered arm for a few months, mow the lawn a few times, ride your bike a bit, and then tell me all about vibro-tactile sensory feedback.
41. Environment-aware prosthetic function sounds like real fun. If I can use it to reliably squirt ketchup on fries one day, hey, why not. Maybe reliably finger through the options of a TV remote control why we are at it. Or do you want to say that your system does not even allow for true couch-potato-ism?
42. So you refer to amputees as "amputees" but to non-amputees as "healthy"? You are from Duderstadt, Germany, and from Vienna, Austria? They teach that there, hm? That amputees cannot be healthy? Dear Otterbock peoples in Austria and Germany, I must tell you that I am very happy not to live in your countries. Your mindset befuddles me. You sure you are healthy? You sure decades ago is decades ago, or are we discussing left overs?
43. Sound great. Now can we build some wrist and hand parts that are not too long? What about error rates and noise ; )
44. The SHAP was a weird test for prosthetic arms to begin with. We never know whether it really conforms to testing norms either (link).
45. The clothespin test is supposed to add "validated" testing to prosthetic arms. For people interested in validated testing, that might, one day, perhaps, be interesting as soon as the very specifics of the test are made a minute bit less obscure (they are as obscure as the SHAP specifics at this point) - i.e., are the pins located and to be pinned to a slightly swinging cord at or above shoulder level, hence representing a real clothes hanging scenario; and, are the clothespins first with grip parts down and then to be mounted the reverse, hence necessitating exactly that miraculous within-palm-flip that is so crucial to the real world clothes hanging experience, and if not, why is the real world clothes hanging experience deemed unnecessary for people wearing prosthetic arms by "test inventors" again, again, again and yet again? Why do you not want us to succeed in clothes hanging again? It is not something I ate, that's for sure. It appears that for the purpose of this test, clothes pins mounted in willful arbitrary artificial ways to rails, frames or hard edges where no one ever would hang clothes. That, folks, is totally weird. Why do you conduct tests for stuff no one needs, does, uses and performs? Leave alone, routinely in large repetition counts (as those are the only interesting ones to trouble shoot trunk compensatory movements if at all). Size, make, elasticity, coating, and spring force of  clothespins all would need to be carefully specified as I can tell you for free that the handling of a clothespin, using a substandard grip either with a human but definitely with a non-human hand or gripper, is totally dependent on whether it is a crappy or a real crappy one. So, yeah, figuring all that our may take another "10 years" or maybe 50. Considering the last 50 years, however, is not forbidden - and from that, doesn't it appear that we are more looking for an anomaly?
46. You need to consider the uses for a prosthetic arm if you want to understand them. It does not totally become clear what y'all are trying to fix, too. The academic establishment, for the most part, has given up "fixing" amputees since a rather long time. They still pull research grants under the amputee excuse. Why not declare this type of science "science different to real uses of a prosthetic arm". As an arm amputee, I really would hate to see my tax dollars wasted for cross label usage of "prosthetic arm" and "testing" when really it should better be called "academic laboratory attempts far from any reality (ALAFFAR)", formerly called "Academic research under The Amputee Excuse (ARUTAE)". And that, I conclude, is a very valid and extremely relevant point.
47. Well, well, well!
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