As we look back on decades of what appear to be functionally not too successful academic research into the construction of prosthetic arms, we can conclude that it is now the time to read them the riot act:
- socket and suspension technology still is a myth for academic researchers; industrial developments are the only advancement that is notable in this domain [bibcite key=alley2011prosthetic];
- mechanical wrist units and cable setups are the main problems affecting heavy duty task performers with their prosthetic arms; there is virtually no research done here whatsoever;
- gripper, hand and hook shape is mostly not determined by any recent concise grip shape analysis or research that was done in that direction; if anything, most designs are probably the result of tinkering, experience and practical thinking;
- myoelectric arms - anything that is commercially available - still operate with two electrodes, just as the Russian Arm did, so absolutely no advancement in over 70 years now, and
- the same problems that affected the Carnes arm after 1908 (i.e., impressive appearance, circus style propaganda, everyday usefulness very limited, insanely overpriced) also affects modern "bionic" prosthetic hands.
So it is fair to say that...:
- academic research into construction of prosthetic arms or hands has one systematical outcome (with a very few exceptions): it does systematically fail the users inasmuch as actually available prosthetic arms or hands are concerned; if however industry based research or tinkering lead to current solutions that actually work, state funded research such as by the SNF (see projects here) or NIH (projects here) should consider pulling their funds from their notoriously well known non-developer projects (i.e., not developing true answers to true questions) and direct their funds towards more appropriate work that actually deserves the title "prosthetic arm/hand research" ;
- researchers that look at prosthetic hands or arms (or pretend that they do) must be really bad chess players; why? Because in chess, if the opponent starts to block your important chess pieces (not so much pawns but the others) then if this slows you down in further chess play, you should treat that with a very high urgency while respecting game rules; so any "myoelectric" device producer that cannot sell their dead stock would have to revise socket technology, and if just simply out of self preservation, as that is the most relevant limiting issue for these types of arms. Instead, prosthetic part producers try to belittle users of body powered arms personally, they sell really badly manufactured parts to discourage body powered arms, and overall exhibit vivid indication of absent strategies that work within acceptable rules of conduct and behavior.
That does not have to stay that way.
Problem definition 1 - to work better
In order to move now, one has to lift up one's butt and get going in terms of research, design and development. More concisely, there is this diagram:
Any job specific skill set that anyone has, or, that comprehensively exists for all jobs [https://www.occupationalinfo.org/] in conjunction (left side of diagram, black bar) is massively reduced (middle of diagram, red bar) by an arm amputation (middle of diagram, red square).
If there is any way anywhere in terms of getting us arm amputees to shlep our sorry asses to the prosthetists, it is by giving us the hope to get back to our jobs, or to any jobs, by aid of useful prosthetics.
Job specific descriptions [examples] (manual activities highlighted bold by me):
- CODE: 663.685-018 - TITLE(s): MOLDING CUTTER (woodworking) - Tends machine that cuts to length and miters ends of molding or shim strips: Slides end-stop against rule to set machine to cut molding of specified length. Slides stock under knife against stop while chopper knife (two blades mounted at right angles) descends automatically to cut molding, or depresses treadle or pulls lever to lower knife that cuts and miters molding. Stacks cut molding on rack. May change chopper blades when blades become worn.
- CODE: 332.271-018 - TITLE(s): HAIR STYLIST (personal ser.) alternate titles: hairdresser - Specializes in dressing hair according to latest style, period, or character portrayal, following instructions of patron, MAKE-UP ARTIST (amuse. & rec.; motion picture; radio-tv broad.), or script: Questions patron or reads instructions of MAKE-UP ARTIST (amuse. & rec.; motion picture; radio-tv broad.) or script to determine hairdressing requirements. Studies facial features of patron or performing artist and arranges, shapes, and trims hair to achieve desired effect, using fingers, combs, barber scissors, hair-waving solutions, hairpins, and other accessories. Dyes, tints, bleaches, or curls or waves hair as required. May create new style especially for patron. May clean and style wigs. May style hairpieces and be designated Hairpiece Stylist (fabrication, nec).
So the prosthetic devices that are build and made available (black squares, middle/right of diagram) necessarily and urgently must address the grip and manipulation requirements of the specific jobs that are affected, and of the job specific skills that are lost by arm amputation.
There was one study [bibcite key=northmore1980] that actually acknowledged there to be relevant job-specific differences in what worked and what did not work, even though their approach was not to construct a specific solution but rather, to compare what presented itself as available options to them:
If you want to define your existence by building prosthetic arms, and by selling any, then you better go quick and analyze the job task lists, filter them for grip patterns that are necessary or even required for certain jobs. The more of these manual skills you can cover with only a few prosthetic devices, the better you are - but it is not the Southampton test (SHAP Southampton hand assessment procedure) that will help you as that specifically avoids and does not contain any job specific manipulations (see description: "with the omission of specific occupational or recreational requirements"). That makes the SHAP a particularly bad choice unless you are really hell bent on showing everybody just how large the extent is of you not knowing what prosthetic arms are usually made and built for. The SHAP is for slow and precise qualitative evaluation of hand diseases or trauma consequences. Not to see whether an amputee would make for a good violin player.
Much rather, the confident prosthetic arm researcher will have to address exactly these job specific manipulations that are relevant and difficult for an amputee at the same time. And if the prosthetic arm constructeur want to sell prosthetic components to users directly and privately, as insurances usually do not cover hobbies and recreational activities, then they may have to cover specific manipulations of these.
Do not be amazed why useless "bionic" gadget toy hands don't sell that well: they were not built for those that are buying, or for those that are paying - and those are employers, insurances and amputees wanting to have a useful prosthesis for work. And just as a remark: tying shoes fast is absolutely not a requirement for anyone. It is only a real requirement for shoe sales people or kindergarten teachers. The fact that no prosthetic terminal device is able to reliably operate scissors tells us that NO prosthetic research - academic, or, industrial - has gone over the task list of jobs in any systematical manner, as hair dressers or seamstresses were left out. However, that would be the mindset you need to start research into prosthetic arms that actually deserves funding. The rest should probably be termed differently.
I just discussed this type of thinking with a prosthetist. He said that this was the absolute and real way to go, ever. I always knew it. But now I wrote it down, so we can all look at it. Hush hush, there is a lot of work to do.
Problem definition 2 - to feel better
The other line of research - trying to make arm amputees feel better about themselves - is on one hand* best addressed by making hard and dedicated efforts to getting them back to very specific and durable solutions for job specific skills (see above) - the importance here cannot be overstressed. And sure, specific activities - playing guitar, certain sports, fishing, bike riding, .. - can make people really happy. And if Bob Radocy, who also is an arm amputee, is the only one running a successful company (TRS) with recreational prosthetic arm add-ons, then all of academia that tag their stuff with "prosthetic arm" or "prosthetic hand" might want to think long and hard what they were doing when that happened.
One has to say that most current prosthetic arms are neither particularly specific and extremely well aimed at making job skill deficits disappear, nor do they offer a specifically well founded approach to an overall improvement of the mind or soul.
With that, current prostheses at best have come about somehow through less targeted approaches. And while some of the prosthetic hooks, devices or hands do have specific advantages over others, they also overlap to a large degree, and furthermore, it is not that much of an increased disability to not wear any as of now, as far as many activities are concerned, current prostheses can actually do not so much more. In fact, a functional point score of my own activities shows that for me, wearing a passive arm or a myoelectric arm (with exception of a very few and very specific activities) make me less functional than not wearing any prosthesis.
But that notwithstanding, or maybe given the poor prospects looking at current prosthetic hands and arms, there is more to life than obsessing over one particular prosthetic aspect. Because on the other hand*, caring for the injured or suffering soul containing functional deficits and disfigurement is not restricted to caring about prosthetic replacement. Even more so: prosthetic devices for arms and hands are so bad, one gets depressed just by considering these. This really is a factor. Too much emphasis on prostheses might end up being rather unhealthy. Better to learn skills on how to cope with no or minimal prosthetic support, keep the expectations low to minimal there, and go for other ways to be happy or at least not too unhappy.
Now, for intimate relationships and what one might do there, NO prosthetic arm or hand that is currently available is anywhere near useful. And that really nails the question, so to speak, what the industry and what academic research have been doing in the department of private life and well being of the arm amputee. That consideration just nails it, full stop. And I do not believe you will have anything succinct to add to this.
And: you read this here first.