ArmWear: Cool Prosthetics - Graduation Report, September 2010, by Marijn Geurts [art / research review]

I was kindly offered to reference, PDF and option to (re-)publish the oeuvre 'ArmWear: Cool Prosthetics - Graduation Report, September 14th 2010' by Marijn Geurts who graduated at the TU Delft with this subject, by way of Dick Plettenburg.

As I pursue a range of art interests in the domain of my own prosthetic arms, I was intrigued to see this piece of work and to see what was made of some of my approaches as the research included some of my 'Red Hand' project (without previously or, ever, consulting me).

I was also surprised to see some of my own photographs and text re-published (rather clearly not taking into account the very non-ambiguous guidelines on my website on how to go about my material).

This, obviously, deserves a closer look and some comments.

Basic research premises

Much research in prosthetic hand or arms appears to base on fundamentally flawed or even non existent premises.

That is why justification for any project is relevant to be checked, and why it must be critically discussed.

Premise: Prosthetic arms and hands are most conspicuous

The report opens with the premise that prosthetic arms and hands are most conspicuous.

Figure 2 (page 6) shows two hands, one is an apparently well camouflaged cosmetic 'aesthetic' hand with red nail polish, there are long black sleeves being worn and yet, the prosthetic hand does stick out like a sore thumb.

I would see this as a correct premise. The point is well made by choosing that particular picture. And I would confirm from my experience that there is no way one can hide a missing hand - with or without prosthetic - using conventional techniques of prosthetic hands and arms. That as such is a simple impossibility.

Premise: Prosthetic arms are too ugly, too heavy, too clumsy or a combination of those blunt descriptors (page 9)

The report points out that conventional prosthetic arms are too ugly (page 9).

"Too" ugly?

Personally, I also find conventional prosthetic arms can be seen to exhibit various degrees of ugliness, ranging from least to most ugly.

And yet there is the cheap plastic charm that cosmetic prostheses seem to exude, this cheap replacement feel of a 70's B-movie prop. Heart warming, ugly, but not not too ugly, I would say.

But if one despises these attempts at cuddliness, I can understand that all is ugly to begin with.

From that angle it is hard to come about a non-ugly design inasmuch as conventional prosthetic arms are concerned.

And now - bear with me here - the report does not say that most of today's prosthetic arms are 'ugly' (which would be bad enough). 

But, 'too ugly'. 

So, this report indirectly suggests that all prosthetic arms are necessarily ugly which is a required viewpoint for stating that some arms, then, exceed the expected ugliness to reach the "too ugly" level.

Let's work on making a hand that is sufficiently but not too ugly?

A prosthetic hand that is termed "too ugly" might, after modification, turn out to be "not ugly enough". That is intriguing, given the reference to the Uncanny Valley.

Furthermore, prosthetic arms are described as 'too clumsy' (page 9).

It would have been one thing to say 'clumsy'. I will agree that most definitely, all prosthetic arms are clumsy to begin with and their innate or built-in mechanical abilities do range from the least to the most clumsy while they are all super clumsy. There are really no non-clumsy prosthetic hands currently and for the foreseeable future, which is, given the actual tangible development in that area over the last 100 years, probably the next ~200 to 500 years.

In analogy to the above, though, one might see a prosthetic designer that redoes a prosthetic arm to not be "too clumsy", overshoot the target and arrive at another undesired result, one that is "not clumsy enough". Eventually, prosthetic designers the will create prosthetic hands that exhibit "just the right amount of clumsiness"? If one carefully monitors and also practically uses these devices one cannot but agree with the assumption that the designers target some "right amount of clumsiness" that is significantly greater than "not clumsy at all".

It may well be that the prosthetic industry does have a role in keeping amputees recognizable as what they are, as keeping them exposed and slowed down and there are indeed concise and hard indicators to exactly that type of mindset - and they would achieve that by providing easily identifiable, sufficiently ugly and sufficiently clumsy prostheses that are neither overly or insufficiently clumsy, heavy or ugly.

Disability, after all, is a spectacle and if it is, then there are people that organize it that way and that act as circus directors.

Indeed, prosthetic industries as well as academic research across all domains do provide indicators to that just behavior.

The user angle is different.

At first you will want and adapt to a prosthetic arm. Then you find they are neither great in terms of looks, nor great in terms of price, definitely not great in terms of function and most definitely not great in terms of comfort; they suck at concealing the handicap and they really suck in terms of maintenance.

From where I am standing, the average arm amputee is well off without too much prosthetics or gadgetry. The social handicap is what makes prostheses so central to the well being and that is where they suck most. There, aesthetics, and function inasmuch as aesthetics are concerned, can be paramount features.

Assume now, that there are two extreme types of non-disabled people, the ones that take offense when seeing a visible disability and the ones that don't. It is exclusively for the first group that attractive and non-conspicuous prostheses must be made. These are the people that might need to approve.

Inasmuch as amputees are concerned, it is what people do with the prostheses that should be evaluated. Not prostheses per se.

Humans built pyramids, humans flew to the moon using relatively arcane technology - and as long as we still have these human brains of ours, there sure as hell there is someone creating art, music, crafts work and doing other stuff such as flying airplanes using simple prosthetic hooks or getting by without prosthetic arms at all.

That, alone, will put all of these futile efforts to make prostheses more or less ugly, more or less clumsy and more or less heavy into some perspective.

The premise of this study implies that arm amputation without cosmesis is visually disturbing and dirty (page 9)

Geurts' graduation report states that cosmesis (that is, covering up the stump with a prosthesis of some sort) has to be (aesthetically) 'clean' (page 9).

That implies that arm amputation indeed comes across as (aesthetically) "dirty".

Admitted, my interpretation is somewhat construed. But not far fetched.

And in fact the author is spot on - visible disability can come across as disconcerting, visually disturbing if not dirty and distressing.

Thus, we take Geurts' hint that visible disability should be aesthetically arbitrated, facilitated, translated, mitigated and mellowed to convey a negotiable rather than absolute impact on everyone's life.

And people do think of visible disabilities as visual clutter - there is significant dehumanization and objectification involved.

I just never read a prosthetic report that outright stated that unprostheticized stumps presented visual dirt and clutter. So far.

But now, there we have it.

Well functioning feedback of a prosthetic hand to the user is stated to be all that important (page 9)

Woweewa. Who would have thought this design oriented report would become that controversial that fast.

The report suggests that pain, temperature, proprioceptive and tactile feedback are "one of the most important issues" for the user.

Marijn Geurts cites three works [25, 36, 38] to support that.

None of these sources corroborate that hypothesis.

From other academic works in upper extremity prosthetics, I know that at time, their premises are completely flawed - quite necessarily so, because how could I live for four years without missing such a major feature?

So let us check these sources.

  • Source [25] is Dan Horkey's website that advertises custom made artwork for prostheses, Dan is not the guy to ask about proprioception or tactile issues. In fact, what he mainly does, is this: he paints sockets, and he wears a prosthetic leg.
  • Source [36] is not research that corroborates the claim that pain, temperature or other such feedback are "one of the most important" issues for the user. In fact that is a book that tries to document some of the current state of the art prostheses and presents a list of available parts. There is no primary research that proves that claim to be true.
  • Source [38] is a lecture or lecture series, definitely not primary research that supports or proves the claim made.

My right hand (when it was still there and healthy) had a very high density of neural receptors, and it mapped to around half of my sensory cortex. Now, my right hand, wrist and part forearm are gone.

That means that to replace its sheer numbers, covering the right side of my whole body with neural interface connectors would be somehow approximating it - but such a setup would be really in the way. Really really.

The two point discrimination of my stump is relatively low. In fact, it is outright lousy. I usually may not even be able to find the way through the sleeve of a crumpled t-shirt.

It is great to have some sensibility at the stump's end but quite frankly, I cannot hit a light switch in the dark a lot better without prosthesis than with prosthesis. 

So in other words, I have reduced sensibility and proprioception due to lack of training and lack of the hand. To overcome that, I will need to switch the light on differently. I need to see before grabbing some item with the prosthetic. So for a few bucks, I will put a motion sensor activated light in my corridor to help me find my way to the bathroom at night. That is what is needed. In fact that is all that is needed.

The prosthetic arm that I wear does not massively cut down on proprioception as such. Much more, I need to protect my stump from cold, heat and mechanical trauma. So wearing a socket and reducing thermal and skin damaging feedback really is the way to go. As I said - the stump does not have all that much going for it in terms of two-point discrimination anyway. 

Given that limited remaining sensory tactile and proprioceptive feedback can be useful, hard coupling to a prosthesis will suffice for most rough and crude sensory feedback situations.

Wearing pinlock/liner or other hard mount, steel wrist and a body powered hook, I can find a light switch in the dark just about as well as with the stump, I can do blind 5+1 style typing just as well with or without prosthetic arm while the prosthesis does correct asymmetrical limb length.

It doesn't have to be a lot more complicated than that. Geurts' report claims, that an amputee such as I would want pain as warning signal for possible damage - and now that really takes the self-defined importance of prosthetic technicians a bit too far. I suffer enough when the prosthetic breaks, I lose function, I lose that arm, it takes me effort, cost and time or organize for repairs - and to additionally inflict pain on my stump there really goes too far. My prosthetic arm must be able to die silently.

No, Sir, I do not wish to cringe in pain when crappy prosthetic parts - as that is what they most often are - fail all the time. If there is any achievement here to be mentioned that would be "one of the most important issues" it would be parts that do not permanently fall apart all the time. Actually, I don't want to feel the prosthetic arm parts falling apart at all.

I see it as technical achievement of our civilization to allow amputees to wear pain- and feeling-free replacement arms and hands. If anything, failure of my prosthetic parts should be transmitted to a pain inflictor on the body of the prosthetic part manufacturer. That is where that feedback belongs. Not on me!

And sensing extra heat really is not at all wished for. Ever turned the meat on the grill using the prosthetic hook and enjoyed this aspect as useful moment of an otherwise inconvenienced anatomy? If anything, could we get the socket with climate control.

Geurts also claims that dangerous situations result from absence of feedback (page 9).

What does he think I am? An ignorant person that predominantly squeezes vital organs with the prosthetic where anyone can see that it just contains simple grip mechanisms?

Amputees, as barbarians, that slaughter and bash, kill and injure, maim and plough through eyes and noses without looking?

Very controversial.

I see nothing dangerous about lack of added sensory feedback of a prosthesis. I get plenty of visual and positional, cable tension related and tactile feedback. I can even feel my phone vibrate when I carry it with the prosthetic. That must be enough. Any extra features will add weight - and I was not planning on carrying all that.

The report establishes an incidence of 0.023% of prosthetic arm wearers in the Netherlands (page 11)

Indeed prosthetic arms and arm amputation are relatively rare.

We are only 0.023% (Netherlands), 0.007% (USA) or 0.01% (global estimate) of the population. This, as I had established earlier, confirms upper limb amputation as a rare disease / orphan disease.

I submitted this issue to a few orphan disease center websites. None replied. To no surprise though: amputees lack a lobby and look disenfranchised - so others feel they can do whatever they like with us.

Given that these attitudes prevail, and given that they are impossible to bear as hairy fat belly bearing grown up adult, one might forgive me here for standing up against these with some vigor and directness.

We are at the mercy of a very few global players in terms of prosthetic components (page 11)

Geurts' report contends that companies building prosthetic components focus on mechanical and technical aspects, not on design or aesthetic values.

That is not entirely correct.

Companies first and foremost focus on their own revenue, on their own cash flow.

Not on technical issues.

For that they usually have a big sales distribution and marketing system - not a big technical development section. They may hire doctors to conduct studies and make it look scientific.

Given the wreckage history of my own collection of commercial prosthetic parts, mechanical and technical proficiency were not keywords that came to mind first.

If ever you doubt this, read this website or send me an E-mail. I will fill you in.

Otto Bock (~4000 employees) and Ossur (~1600 employees) both lead global prosthetic component production according to this report.

I am not even sure how Fillauer (~140 employees) compares as it contains subsidized companies (such as Centri or Hosmer) as also, Centri and Hosmer have rather good products.

However, there are some remarks to add here.

There are single individuals that make a massive difference.

They are Randall Alley (Biodesigns), Bob Radocy (TRS), Bradley Veatch (Toughware TRX) and Mert Lawwill (Mert's Hands) as well as Roman Meili (PUPP+CH+EN).

Their products go far and beyond what are available elsewhere and they exclusively focus on mechanical and technical aspects.

Also, Hosmer's hook collection contains some of the most useful parts you can wear if you also have a hosed arm like I do.

There are truly aesthetic component manufacturers.

Centri fabricates cosmetic gloves that one can also custom order. There are a number of silicone gloves that look really great - among others, Regal Prosthesis, Kingsley, and a few more.

Then there are people offering customized looks.

Geurts makes no mention of this obviously - but every technician can and will add color, textiles, artwork and paint to a prosthetic part if asked and inclined to do so.

There is Dan Horkey with his GTOPI firm.

And then everyone else customizes every other aspect of their consumer product covered life anyway. So there is the option of getting artists, seamstresses, of adding consumer parts to one's prosthesis and many amputees do that already since a while.

Even Pillet or other silicone lab specialists will be more than happy to try out new looks and appearances if asked or involved with such demands. There are also dedicated art projects that cover prosthetic arm art.

Last but no the least, the Uber-Geek in terms of aesthetic prosthetic hand construction is Jacques Monestier.

His achievement appears to be largely ignored by most people in the field, be it as user, technician or academic.

A thing no one seems to realize that not only prosthetic hooks are very functional - there is one prosthetic hand that offers both precision pinch grip and adaptive grip at once - that is the Becker hand.

Why is everyone acting as if prosthetic hooks are ugly and Monestier and Becker hands do not exist? 

Why are new re-inventions of adaptive grip hands lacking the sophisticated state that the Becker hands attained over their ~60 to 70 years of manufacturing?

Becker hands also fit into average sized and average shaped gloves. That said, all cosmetic options that are open to anyone are open for people that wear a Becker hand. Get a work glove, get a carnival glove, get a fashionable glove - and it will fit on the Becker hand.

As a matter of fact, when Geurts typed up his report, I had already been sewing up custom gloves and re-fitting acrylic color design for my prosthetic arms for a while.

So we are indeed living with a lot of small cale improvements and marginalized industrial approaches, inasmuch as appearances are concerned.

We are at the mercy of the global players but in a way, the global players depend on us, the clients, and our needs and moreover, on the state of our emancipation. I still wait for Otto Bock to apologize for reaming me for their el-cheapo bolts - but I realize just as it took the Catholic Church a while to apologize for Galileo Galilei, that Otto Bock perceive themselves as similarly to such a church. So patience is in order.

Also, looks are looks that I can implement with the partners that I choose. Even if I swim in money, I am not sure I will spend 50'000 to 80'000 bucks on corporate junk.

Historical perspective (page 13)

It is stated that "since the beginning of time, prostheses are made to resemble the body parts they are replacing".

In a way Geurts is right if he narrows his view to contain only prosthetic limbs.

As we know however through reflection ourselves, through discussions and also by following Amber Case, prostheses, prosthetic devices, generally, can have any shape, function or appearance generally.

So my first really important prosthetic adaptations as arm amputee were getting an ultrasonic tooth brush, getting my bike and car adapted, and getting fast zip thingies for my shoe laces. Not getting a prosthetic limb.

It is absolutely correct to say that the body powered arm (still) is the most functional prosthesis.

Conversely, myoelectric arms never achieved the same degree of low weight, extreme intuitive control, affordable setup and speed.

The future however might not follow what Geurts projects - neurologic actuation and feedback. Much rather, the future will see amputees following a range of tracks concerning their prosthetic arms.

Only a very few will cease any pre-amputation activities, adopt Otto Bock's Michelangelo hand or Touch Bionics iLimb, act and work as advertising individual and poster boy or poster girl, and thus avoid all hard manual labor. Those, I will predict, will be the very few, far and out. Even here, might I suggest to keep a sharp eye on overuse problems.

A second group of individuals will be like me.

Obsessed with manual activities and hobbies since decades, obsessed with physical activities since decades, they define themselves over frequency and strain, over kilometers biked and over hills climbed. They will keep raging through life in full knowledge of that, and they are - as me - well networked. I knew from early on, that experienced physiotherapists all and without exception told me to use body powered technology and to push that for at least five years. I knew from early on, what inside stories were told about microprocessor controlled prosthetic legs. And I knew from early on that body powered concepts and the crap sold by technicians that try to make me want a myo arm as that's where they ream their percentage dollars off are two different things altogether. Also I am fast to learn and it was not hard to find out what games were being played there. So I knew from early on who sells, tells, and fakes what fairy tale. I knew and still know that I am following a track of people that demand healthy and safe motion in many aspects - and so in all likelihood, there won't be a prosthetic arm that keeps me from pursuing that.

The third group will be the largest group of customers. Those are mostly people that get what their technician tells them to get. Until hell breaks lose. Then they get the next best thing. - Many will start wearing a body powered hook or arm that breaks frequently (due to crappy parts and poor build) and that has a harness that compresses and damages their other arm's nerves. That slows them down enough to be good candidates for the industry's money horses - myo arms. After wearing myo arms for a while they will further overuse their remaining limb and also run up shoulder problems on the amputated side which them will in all likelihood ground them completely but sell some surgery and medical treatments on the way down. So, that's that.

Parallel to that and without the slightest regard for real concerns there is academic research called "prosthetic arms", "prosthetic limbs", "prosthetic hands", you name it. Practically nothing they do will ever appear in the real life theater as outlined above. There are notable exceptions - such as this report - but they are extremely rare. Research money into prosthetic arms typically is wasted.

So in fact Geurts is (in my view right by) stating that our best chance is to maximize body powered technology. That, really, is the current vision of actual upper extremity prosthetics.

Children reject prostheses (page 17)

Children - with a very high capacity to learn - will reject prostheses with rejection rate peaks both after getting them and in puberty. So many kids cannot be wrong so let us look at possible reasons.

While children missing an arm may not lag behind in developing skills for what are considered bi-manual tasks, it is completely unclear why they reject prostheses.

Here, Geurts' report suggests that rejection is because of the inferior looks of prosthetic arms. These, it is then brought about by further sentence juxtapositioning, is somehow linked to anxiety and depression.

Of all aspects of prostheses, appearance and looks are easiest to modify. They are the first aspects to get changed if the amputee insists, purchases colors, or whatever else. My high school buddies and I painted anything, from motor bikes to walls, if their original designs were not cool enough. Where are these people different? And they are different, obviously, as claiming an appearance issue as reason for rejection makes no sense. It is nothing but a silly excuse.

I agree however, that expectations of prostheses are not at all well presented, neither to adults nor to children.

Geurts correctly states that Star Wars, Iron Man and similar movies do not necessarily help to build a clear understanding of what prostheses are there for.

In particular, there are a few real myths:

  • looks will not be improved, and if one listens to current myoelectric hands, noise is a factor too; always, prosthetic arms will be standing out and never will they blend in too well
  • intricate and anatomical hand function can only be approximated at a cost; that cost is massively reduced stability and robustness and increased weight
  • prostheses can only serve hard or even extreme work if they are light weight - suitable for many repeated lift / elevation actions - and very robust, thus, simple in terms of design
  • over 5-10 years, many arm amputees either stop being active manually to preserve their remaining arm and hand, or, they might suffer overuse problems that can be rather serious
  • to avoid these, prosthetic arms will necessarily be technically robust, light, simple, very comfortable and healthy to wear long term; with these, any propagated myths are dumb, dangerous, stupid, and very expensive as health damage can produce costs beyond that which can be fixed with more money
  • given that an iLimb costs are rumored 80'000 CHF, and given that the Otto Bock Michelangelo hand is rumored to cost around 90'000 CHF with another 10'000$ for warranty extension, and given they additionally burden rather than alleviating work for the remaining arm / hand, one may most seriously doubt rational thought for such purchases even more so as these are awkard looking, stiff looking, noisy products
  • telling that to another person requires attention and time and interest

Insecurity is a further factor. Body image and self appreciation are hard to come by anyway, and even more so in a society that allows for public ridicule, that supports extremely narrow limits for what is considered beautiful, and that by and large puts appearance over function, shape over action, beauty over performance.

From the inner workings of my own response to societal pressure, also in response to what people told me, I could add to that the following points:

  • I see that society demands that I conform to certain expectations regarding looks, appearance, body image
  • I realize that there is simply no way for me to actually conform
  • I will always be a non-conformant person with this disability, and my conformance will only be measured on a negative scale - i.e., there will be "not quite conformant" or "not at all conformant", but no positive values
  • I see this as an instrument of power that I do not approve of
  • I will present any appearance that may be construed as "conforming" more or less on my own terms, not on terms that society dictates - it's a pride thing if one already is stamped off as non conforming
  • Quite necessarily, prosthetic hands and arms will largely be valued other than through their appearance alone
  • In other words, given that society does not offer me a positive ranking with a prosthetic arm (only shades of negative), I might as well heavily value originality, individual expression and, first and foremost, function

As Geurts suggests, disabled people manifest different personality factors than able-bodied people. These include increased anxiety, increased depression and impaired self-concept.

That in essence surely may be true in part, and yet, there are other factors I see playing a big role. People with an amputation also find themselves...

  • required to conform to a lesser degree due to an overall status as outcasts
  • far better trained to speak up, to intervene, to cut off dumb ideas, to dish back, and to stand up for themselves as that is also what years of exposure to a discriminating, belittling public, careless insurance handling and other such societal implementations will do to a person with a disability
  • really asymmetric to a point where thorough physiotherapy and gymnastics are required (not a re-coloring of the prosthetic)
  • confined to adjusting their body image not just to societal self made illusions, but to real serious problems such as overuse injury, asymmetry and subsequent dysbalance, actual pain, unsightly skin problems on their stump, so offering insurance and professional support for such problems - rather than designing a neat looking outer shell - is really a relevant solution to a better body image
  • confronted with money making schemes of prosthetic technicians - given these earn up to 30% on any sales made, they are far more likely to build and recommend ill fitted weight anchors with little functional benefit such as myoelectric arms, rather than building really comfortable liners and sockets, body powered cable systems and anchor points that only sell for a fraction of the price
  • confronted with the fact that NO prosthetic arm or hand is really so extremely functional

Since all that can be overwhelming and since it can be difficult to get one's own way in terms of prosthetics, a number of amputees will give up just because.

Prosthetic technicians can have a strange air about them with a fair number probably being so-called devotees, and dealing with that as such - sucking up the strange vibes, dealing with their inability to really focus on factual matter since they can be visibly distracted when facing a stump - may require strong nerves.

At an age - puberty - when rejection is a great way to become less dependent, rejecting prostheses will entail the rejection of a whole batch of dependencies - prosthetists, doctors, insurances, and so on - so from point of view of the amputee, it is not hard to understand why the overall situation generally is rather inviting to reject prosthetic arms and hands.

Geurts cites studies that show only full time workers (I work full time and like my prosthetic arm) have a rejection rate as low as 20% - other categories of users, including students, reject their prosthetic arms in up to > 40% (Biddiss, Canada).

According to another study, rejection reasons were function (> 50%) and comfort (almost 50%). Appearance, teasing and others rated far lower.

It is the overuse symptoms and chronic asymmetry that are the reasons why upper extremity amputees come back to wanting prostheses. And the option to give a complete appearance. We already agreed that prosthetic arms are most conspicuous so all you can treat is how one feels about it and how, in detail, the things ends up looking.

Artificialness (page 23)

The study then cites the theory of the Uncanny Valley. That theory holds that anthropomorphic objects may look repulsive if mimicking a human too closely but may be more accepted with a more artificial or alienated appearance.

The theory is not proven and there are situations where I would argue it is not true. But then, the subject is complex. It is generally agreed on that the Uncanny Valley theory is useful for upper extremity prosthetics as well as it useful for facial appearances in movies.

Secondly, not just the static appearance itself appears to cause an immediate emotional effect of rejection. It is the way it oozes moods, the way it blends with the wearer, and the way it moves.

On a more rational level, human likeness attracts factual comparison to human reality, human function.

Quite correctly in my view, Geurts concludes that Mori's Uncanny Valley may well be influenced by other factors that could mitigate or blow up this Valley effect.

Bionic hands (page 31)

With so-called "bionic" hands costing as much as 90'000$ just for the hand piece itself (Otto Bock Michelangelo hand, rumored price), it is a question what such a product achieves.

It is my view that a myoelectric arm of that type can well cause a perceptive distortion field for the user.

A user affected by it will perceive the product as absolutely perfect in every aspect. That effect is known already from the times when the Germans bought the Carnes arm patents: the product is extremely expensive, it costs a fortune, it actually and orthopedically improves little to nothing and after a few months or years, it will be a nuisance the owner will want too shed, to put away. Then, retrospectively from that moment on, the product price must be calculated.

And yet, such a distortion field may just be great to get. If the price is right.

Function, and prevention of overuse problems, are not a factor that is evaluated when insurances or users buy these hands. I am aware of a number of myo arm aficionados that all suffer from extensive overuse problems, so that being at least anecdotical evidence, will make my point - if you are inside a reality distortion field of a bionic hand you will readily sacrifice your remaining hand to overuse - simply because "bionic" hands may not deliver all that there is to deliver.

Art and aesthetics (page 33)

This section lists a number of private projects that address the appearance of prostheses.

In addition, it should be mentioned that anyone can change the appearance of their prosthetic limb themselves. The amputee also is an active person that can work out stuff themselves.

These are options for art and aesthetics that I can apply myself:

  • I can spray paint my socket.
  • I can carve my socket.
  • I can use brushes and pens on my socket.
  • I can get anyone to do the above to my socket. In fact I once got a professional car body shop guy to redo my paint job.
  • I can sew a cover or sleeve for my socket myself.
  • I can get anyone to sew such a cover or sleeve for my socket.
  • I can talk to my prosthetist to include color and structure when making the socket.
  • I can make a socket myself.

I believe that amputees are active as much as they can, and most are looking for means to solve their own problems in a practical and affordable way.

Getting a prosthesis (page 41)

Here, Geurts describes a process of getting a prosthesis.

A cast of the stump is made.

The socket is built.

That's it.

The expert interview (page 47) is interesting in that the specialist, Prof. Hans Arendzen, rehabilitation specialist, opines that there be two groups of prosthesis wearers that he sees as opposing. One group according to Arendzen wants to camouflage their defect. The other wants a functional prosthesis or no prosthesis at all.

I never saw that as opposites though. Depending on the situation, the one or the other type of prosthetic arm is more adequate, or, none at all is the adequate way to go.

Arendzen suggests that wearers of functional prosthetic arms convey the statement "you have to accept me for who I am". Which implies that cosmetic prostheses achieve a different goal.

That statement ignores a massively relevant fact - even the most cosmetic looking arm and hand sticks out like a sore thumb. In other words, there is no way of hiding.

Not once you interact with people directly, once you eat at a table with others, and not once you get to work. The problem is not whether a prosthetic arm is functional "or" cosmetic. That is not a question that arises. The question is different.

Last but not the least, appearance does define who I am. Think about it, if necessary long and hard. You may not believe it? Paint your face dark blue and try getting on an airplane. Then report back here.

Product emotions in arm prosthetics (page 53)

A research tool called Product Emotion Measurement Instrument (abbreviated PrEmo) is then used to investigate reactions of people towards different appearances of prosthetic arms.

People that were asked to give their opinions are basically three groups:

  • Children aged 12-14 that are "prosthesis wearers",
  • Children aged 12-14 that are "peers", and
  • Professionals that are "prosthetic therapists".

I find it relevant to note the absence of the following groups among the raters:

  • Children aged 12-14 that are arm amputees but prefer not to wear a prosthetic arm; I assume they have a substantially higher degree of self confidence.
  • Older arm amputees that do or do not wear a prosthetic arm; I assume their opinion towards prostheses are better defined and more.
  • Fashion designers. How can their taste not matter.
  • Dieter Bohlen, Simon Coward. How can their taste not matter.
  • Prolific prosthetic arm designers. Dan Horkey, Peter Kuschnigg, Becky Pilditch, Wolf Schweitzer (myself). How can our taste not matter.

Thus I contend that relevant opinions were withheld.

They were presented with:

  • Hand shaped prostheses
  • Hook shaped prostheses
  • Leg prostheses

Here are the results of that study (point scale 0 to 4, black). Each prosthetic arm or leg was rated in terms of both positive and negative emotions.

As it appears, any of these prosthetic appearances can elicit both positive and negative emotions.

  • Where positive and negative appearances balance each other out, one might assume a social wearing experience with less aggravated tension.
  • Tension might result from one or the other dominating.
  • When positive emotions prevail, people might feel urged to elevate the prosthetic to be the focus of their remarks such as compliments or questions, praise or undue happiness. They raise the already unusually shaped prosthetic into the focus of their positive attention. That however is not where it belongs.
  • When negative emotions prevail, derogatory comments, satirical remarks or social exclusion might ensue.

As I tend to be interested in people behaving as themselves, low tension would be what I want my prosthetic arm to elicit in others, regardless of my own opinion. So, lowest tension with teenage peers (and professionals)

Thus, I used Geurts' resulting scores (figures in black) and determined the difference between positive and negative scores to approximate whether tension (colored values) would be low or high.

The results were ranked with best ranks for lowest tension, and worst ranking for highest tension.

Discussion of results below the table.

Model of prosthetic Teenage prosthetic wearers Teenage peers Professionals Tension rank according to absolute value
Tension up to 0,2 Tension 0,3-1,0 Tension over 1,0
Conventional skin colored prosthetic hand positive 1,8
negative 0,1
Tension +1,7
positive 1,5
negative 0,8
Tension +0,7
positive 1,1
negative 0,4
Tension +0,7
Teenage wearers: 7
Teenage peers: 4
Professionals: 7
Becker Red Hand positive 0,2
negative 2,2
Tension -2,0
positive 1,0
negative 1,2
Tension -0,2
positive 0,8
negative 0,7
Tension -0,1
Teenage wearers: 9

Teenage peers: 2
Professionals: 1,2

Design model Immaculate prosthesis by Huseklepp positive 0,8
negative 1,7
Tension -0,9
positive 1,5
negative 0,9
Tension +0,6
positive 0,5
negative 1,1
Tension +0,6
Teenage wearers: 3,4
Teenage peers: 3
Professionals: 6
Split Hook WILMER positive 1,0
negative 0,8
Tension +0,2
positive 0,5
negative 1,6
Tension -0,9
positive 0,4
negative 0,9
Tension -0,5
Teenage wearers: 1,2
Teenage peers: 6,7

Professionals: 4,5
LESA gripper with carbon arm positive 0,6
negative 1,6
Tension -1,0
positive 0,7
negative 1,6
Tension -0,9
positive 0,7
negative 1,2
Tension -0,5
Teenage wearers: 5
Teenage peers: 6,7
Professionals: 4,5
Split Hook WILMER (colored) positive 0,7
negative 1,6
Tension -0,9
positive 0,5
negative 1,8
Tension -1,3
positive 1,2
negative 0,4
Tension +0,8
Teenage wearers 3,4
Teenage peers: 8
Professionals: 8
Ossur Cheetah Legs positive 0,9
negative 1,1
Tension +0,2
positive 1,3
negative 1,2
Tension +0,1
positive 0,5
negative 0,8
Tension -0,3
Teenage wearers: 1,2
Teenage peers:1
Professionals: 3
Eames style leg positive 0,5
negative 1,8
Tension -1,3
positive 0,8
negative 1,6
Tension -0,8
positive 0,5
negative 0,6
Tension -0,1
Teenage wearers: 6
Teenage peers: 5
Professionals: 1,2
Nike Sports leg positive 2,2
negative 0,3
Tension +1,9
positive 2,8
negative 0,3
Tension +1,5
positive 2,3
negative 0,1
Tension +2,2
Teenage wearers: 8
Teenage peers: 9
Professionals: 9

Adults (professionals) rate the Red Becker hand with a surprisingly low tension value. So do teenage peers. That means that other people can be rather relaxed around it. The only people to rate the Becker Red Hand with high tension are teenagers wearing it. This is very interesting as it shows a total bifurcation in perception.

Users and adults rate hooks as "low tension" whereas teenage boys that are not disabled seem to rate very high on the tension scale. This perfectly coincides with a text analysis of legends about hooks and severed hands: there, also, fear and anxiety seems to affect pubescent boys, first and foremost. Accepting a hook as prosthetic device thus seems to require maturity.  In itself, an adult mature audience seems to have absolutely no problems with hooks.

And despite the branding, overall feelings are tense over the "Nike sports leg". In a way this could be because with such a "good looking prosthetic" due to the brand fame claim, the prosthetic (and with it the disability) becomes a center stage piece, it illuminates the "freak show" aspect just a bit too much.

Product emotions in arm prosthetics: statistically significant differences

  • Becker red hands elicit "boredom" to a significantly lower degree in professionals than in wearers.
  • The skin colored split hook elicits significantly less joy in professionals and peers than in wearers. The skin colored split hooks elicits significantly more fear in peers compared to wearers.

Product emotions in arm prosthetics: conclusions

Emotions regarding prosthetic options were interpreted.

Geurts assumes that it is good to elicit positive reactions. Such as the Nike leg design would provoke. Also, it is assumed that it is good to have a prosthesis skin colored. It is furthermore proposed that a mismatch between the prosthetic arm's color and the real skin color would be perceived as less positive and that, as such, would be a bad thing. Hooks appear to be perceived as frightful and disgusting by all groups. In particular, teenage peers do not like hooks.

I see positive reactions not as desirable as a balance between positive and negative reactions. An inert piece of ground, a uninteresting newspaper article, any of these will elicit everyday experience type of non emotional reactions, particularly as net result. That is what I see as goal - a neutral appearance, a prosthetic hand where people go, Oh!, a prosthetic hand! and with that, they get on with it.

The winners for net tension to be low - for other people (not necessarily the user) feeling at ease - clearly are the Becker Red Hand (arms) and the Ossur Cheetah parts (legs). Both are very functional - the Becker hand is the only mechanical hand that is both very durable and has an adaptive grip, light weight, robust and silent; the Cheetah legs win championships - and both look different from an assumed skin colored average stock model one would expect from the average prosthetist.

It is relevant to note that the Red Hand constitutes an anomaly in that wearers rate it a lot more negative than peers or professionals. It requires social awareness to wear a Red Hand as one has to actually overcome one's own fear of using that color. Conversely, the split hook is preferred by many wearers but rated quite low by professionals and peers. Who would have thought that.

Interviews (page 79)

Amputees were also interviewed in more detail to recover some information about their needs, views and concerns.

Self focus.

It appears that "the most important" requirement for a prosthesis "undoubtedly" is reported to be "looking like what you should normally have" - that is,  prosthetic arm should look like a "real arm" in shape, color, and (!) motion.

All things, aspects, parts, or portions of the prosthetic that deviate from that expectation should be covered.

At the very same time and simultaneously, "people want their prosthesis to be unique", and "personalizing it with a colorful and conspicuous print" apparently "is appreciated".

Activity focus.

Swimming "is possible with a passive prosthesis".

Powered prostheses are "more fragile" and have to be used with more caution.

Correct wording. "More fragile" (and not "less robust"). 

The average cosmetic glove has to be replaced every two months. Specific activities can also make the gloves very dirty. Apparently that "causes" the wearers to "always be careful" and cautious with everything they do - such as household chores, outdoor sports, gardening and garage work as well as touching surfaces of any kind, writing, or reading newspaper.

Product focus.

Wearing comfort, functionality and the inconvenience of recharging myoelectric arms' batteries are concerns.

Now, there seems to be a bit of a hystery breaking loose here. It appears that prosthetic arm wearers are extremely insecure and of course they do not know what they want. Also they are the only ones from all participants that did not appreciate the Becker Red hand for what it is - a humane looking, customized and impossible to oversee unique statement of prosthetic replacement. That heartfelt absence of maturity explains why at the same time, the prosthetic arm has to blend in perfectly and be personalized and colorfully unique.

I can tell you that for colorful and unique appearances, you need balls. The people asked here, they mostly have no balls - they might grow them one day, but they are still about to go through puberty. They are scared shitless. As it appears, that paralyzes everything.

No arm amputee in their sane mind that I know of would ever swim with a prosthetic on. I qualified for and participated in the 2012 FINA World Masters Championships over 100m crawl swimming - with an IPC S9 classification, and that being a non-disabled world championship that is rather hard to qualify for. Without wearing a prosthetic, mind you.

So I really do not know what these people told Geurts and what of that he believed. I can ride my bike without prosthetic on, with hook, hand, or optimally, wearing the Mert hand, a specific handle bar solution for arm amputees. And with art being art, my dark brown or red PVC gloves last relatively long, like, half a year or longer. Also, I wear hooks for tooling or scrubbing around. I might miss a part of an arm but that does not mean I cannot use my brain to sensibly go about things with relation to my terminal devices. Who ever cared about myoelectric arms? That was a gadget invention to begin with, surely not meant to be taken as a serious prosthetic arm technology.

Designing cool arm prosthetics (page 89)

Frank Jol - an interviewee and "orthopedic instrument maker" - says the market for arm prosthetics is extremely small. While there are considerably less arm amputees (than there are leg amputees), not every arm amputee owns a prosthetic arm, and not all owners use their prostheses every day. Also, Frank Jol says that prosthetic arms are considerably harder to make than prosthetic legs. He further specifies that arm prostheses for sport are even fewer and rarer. Also, after the age of 16 of the client, insurances practically never finance customized work or sports prostheses. Also, Frank Jol apparently said that people indeed want to - at the same time - appear humanly and at the same time be different than others. Then, he adds that one single prosthesis can never be suitable for every activity.

So the product profile for a prosthetic arm for transradial (below elbow) amputees should cover these aspects according to Geurts:

Humanly appearance. That as Geurts perceives it is relevant to avoid the "uncanny valley".

Activities. Geurts finds it important to have a prosthesis that can change balance between appearance and functionality since these two are implied to be mutually exclusive.

Personality. Other than being humanly and flexibly fashionable or functional, a prosthesis also must be unique, fit personal taste, fashion, culture and lifestyle.

Self-confidence. Prosthesis wearers as Geurts puts it do not have functional disadvantages. He thinks that they learn to live with one arm and adapt perfectly. All they suffer from is societal pressure. It results in feelings of insecurity.

Context. Prosthesis are worn basically in situations requiring casual, sporty and chic. Also, some hobbies can require a functional prosthesis.

Ultimately and without going into too much detail of Geurts' generalizations, he then decides that concept design of a cosmetic glove for an existing prosthetic hand will be the answer to the problems that are mentioned.

Concept design - Integro, Arm Wear, Di Guanto (page 105)

The concept being developed or presented here contains

- a glove with arm cover

- containing a glove grip surface

- to be worn over or covering the cosmetic glove

The person description to introduce the targeted personality is called "Alex". Alex is described as "born with only one arm" even though the rest of the text suggests that he has an arm but is missing a hand.

So maybe it does pay to go through correct terms for body parts also in relation to limb loss or limb deficiency? 

We never learn, however, why Alex feels better wearing Adidas, Nike or Puma branded items.

More importantly, we also do not learn what type of prosthesis - passive, body powered, myoelectric - it is that Alex usually wears, or, that he intends to use for soccer.

That however would be quite relevant given that he is about to wreck that part in soccer training and game play.

The glove then is described to be user modifiable in terms of print, pattern or grip surface color.

We do not learn about the exact grip surface specification however.

We then learn that Sara, another persona to be introduced, was born with "only one arm".

Likely she does have an arm but we are not told any of that. We are told that she was born without prosthesis, though. She now likes to wear a self designed glove cover for the concept glove that is introduced here.

We are then told that "everybody wants to be unique" (Fig. 76) but all people here seem happy, and, they all seem to have two hands.

While a "Harris" profile (Fig. 77) seems to "evaluate" these three concept gloves against each other, grip is key. For that, nitrile or gecko skin type surfaces need to be cheaply replaced every 1-2 weeks. Grip surfaces are like tyres - one needs to be able to swap them as fast as Formula 1 race cars can get their wheels swapped: every second counts.

So far, Becker hands by far win this race because commercially available high tech gripper gloves can be swapped within minutes by the user. So for 1.50 do 4.00 USD, you get a fresh totally new cool looking super grip glove.

And that beats all other criteria listed here. Atlas 370 gloves are feasible, cheap, inconspicuous, cool, have a great grip, and fit any normal hand or Becker hand alike. Trying these out in endurance tests will show you that easily. Any type of activity, from eating ice cream to fixing bicycles. Anyone can do such testing. 

The works continues showing us that "a prosthesis must be suitable to live an active life with" in Figure 79.

The woman here is wearing a TRS gripper - not a concept design glove of any kind.

Armwear assessed (page 123)

The Becker hand has been redesigned as green, and it has been ornamented with - apparently unauthorized - usage of the "PUMA" brand.

As it is, this design now gets the highest positive and low negative ratings by "teenage peers". Also, skin colored arms or hands are rated really well. The Becker hand, and a bit less so, skin colored hands, are located closest to the tag "pride" (Fig. 83).

Prosthesis wearers however - as seen above - seem to differ from the peers' perception once again.

The assessment shows, that prosthetic wearers in their teens prefer different designs from their peers. Treating this situation however points to letting them know "how the other side feels" - not to give them something they can accept without education or training. Sooner or later, they will have to face the fact that their perception is off.

Pride is best shown by wearing a red Becker hand and red socket. Trust me on that. I developed it exactly for that. It works like a charm. However, depending on their personality, the wearer may start feeling like they are sitting on a space rocket : ) not so the others, the peers.

Concluding remarks

This study is great in that it addresses a highly relevant aspect of prosthetic hands and arms: appearance.

This study is ground breaking in that actual ratings are taken for various appearances. There never has been  such a study before.

While a number of aspects seem to be a bit strange, confusing, lacking in detail or oversight, this is an overall fun work to read. It is a great food for thought.

This line of research is relevant and it should be pursued further.

Disability discrimination

On a technical note, I had not been approached by the researcher despite him using ample photographic and textual material of my website against a rather clear restriction for such usage. He even features a full size image of my face (page 36 / figure 39) snatched from my website. At a meager resolution. Wah.

My shit ain't free game though. Particularly not my face or a photo of me. Other researchers realized that - because after all, how hard can it be to read the instructions. They got in touch with me before marching happily into the sunset. Moreover, I usually supplied them with high resolution photographs or specific new image series so they were optimally documented.

As opposed to contacting me, Geurts seemed to be quite comfortable to get in touch with non-disabled artists Becky Pilditch or Ingrid Van Voorthuizen about their prosthetic projects.

Extensive thank you notes were laid out in Marijn Geurts' text to others. But he conveniently failed to mention that he used unauthorized material of me, a disabled person, or, my name, at his acknowledgements and credits.

I am painfully aware of the fact that non-disabled people constantly feel the need to overstep boundaries, to use and abuse whatever they can snatch from people with disabilities without considering simple rules of conduct, etiquette or behavior also applying to us. He could have obtained better quality shots from me and avoided this remark here by doing this a bit differently.


[1] Geurts (2010) Arm Wear: Cool Prosthetics - Graduation Report, September 14th 2010 [zip]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - ArmWear: Cool Prosthetics - Graduation Report, September 2010, by Marijn Geurts [art / research review]; published October 29, 2013, 06:04; URL:

BibTeX: @MISC{schweitzer_wolf_1582451087, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - ArmWear: Cool Prosthetics - Graduation Report, September 2010, by Marijn Geurts [art / research review]}}, month = {October},year = {2013}, url = {}}