Current new developments in hand prosthetics are the iLimb (TouchBionics) and the Michelangelo hand (Otto Bock). Both are termed bionic hands. As these could be seen as very attractive, emotionally appealing and extremely expensive, they are a fascinating subject to examine.
This post also precedes some of my more refined attempts at defining, describing, specifying, evaluating and actually comparing prosthetic performance, such as a variation on the Carroll test.
One thing that amazes me is the obvious discrepancy between the feelings of the wearer (inside) and the feelings of the person watching the wearer (outside): when watching someone else wearing it from the outside, the iLimb - as I felt - looked artificial, stiff, slow, performed extremely loudly and to me appeared to be rather annoying, just as a car with a defective exhaust when seeing someone else wear it. Yet, operating it myself sucked me into a dream world of simulated hand function that I viewed entirely differently and it put a wide smile on my face. Seeing someone else smile at their own iLimb and witnessing the obvious discrepancy between its artificial appearance, slow and very restricted functionality and noisiness on one hand, and the smile it put on the wearer on the other hand, then completed a rather distressing experience to me.
It is ultimately the question why am I wearing a prosthesis? Is it merely a highly priced conversation piece, an item to wrap oral history around, a think to talk about such as the iLimb that is a the centerpiece of a large series of mostly social parading of the prosthetic object? Would I spend a staggering 78'000 CHF of my own money just to get someone tap my shoulder in a grocery store saying, "congratulations to your fine prosthesis, one can hardly see at all that it is an artificial limb"? See how much is that in dollars! I wear a prosthesis to show to others that I am willing to fake having a hand, I wear a prosthesis for sheer functionality. I'd wear one as fashion statement but for that, a self-funded 78'000 CHF hand necessarily must combine computing and programming options of a top-of-the-line workstation (huge one available for 15'000 CHF), the mechanical properties of a luxury class car (50'000 CHF), the stability and ease of handling of a Bosch drill hammer (1'000 CHF) *and* the battery or energy functionality as well as versatile electronics of a top-of-the-line laptop (available for 8'000 CHF). And we start off with a head start for good old mechanics here - the hook relaxes people as they see within a mile against the wind that I am missing a part, that there's a standard item to replace some of it, and it is also one reliable piece of hardware (even though we had to work on that both for the wrist and the hook).
The fluency and immediacy of available motion is an extremely important feature for my hook or mechanical hand. An experienced physiotherapist told me to go for a body powered prosthesis if only for that reasons - and stick with it for a couple of years. He said that only then will I grow into using it so much that I will really be able to rely on its advantages. The argument of fluency and immediacy becomes apparent when comparing the iLimb in its respective appearances on YouTube, and my hook in the following videos. And recently I realized that one cannot thoroughly get accustomed to such a prosthetic setup without letting it grow on oneself, without allowing oneself to naturally incorporate its function into one's life.
In response to TouchBionics "get a grip on functionality" demo videos http://www.touchbionics.com/professionals.php?pageid=44§ion=5 I recorded similar activities using the Otto Bock MovoHook 2Grip for 1:1 comparison. My evaluation bases on my current personal requirements as a right below elbow amputee.
Recently, detailed accounts of iLimb usage by Darin Sargent (see: theadventuresoftheilimb.wordpress.com) highlight activities such as reading a newspaper or working having it on in the kitchen. As I see it, Darin Sargent really and ultimately tells us throughout his extensive online video collection that basically he was real lucky to get insurance to pay for the iLimb (he did not pay 78'000 CHF) but it appears as if the product was never formally evaluated by his insurance for function or performance.
As his website articles imply, he uses it more as a social prop than as a functional replacement. And we learn that his insurance paid for it. That is like learning that they just finished a gold toilet for the king. Maybe that is nice for the king - but I really see no further conclusion to be made. His website implies that Darin has no idea how to conduct a technical evaluation and he even uses words that indicate that he looks down on people that go down into the pits and actually have to rely on their prostheses for work. If he despises manual labor and the big problems that come with evaluating prostheses for that purpose he has every right to say so. If he looks down on people that wear hooks for performance and hands for appearance I don't care - maybe that's what he has to do.
So the overall impression I get is that yet another high ranking army officer / priest / motivational speaker / retired person walking around with a hugely expensive dummy hand prop is not a very good ambassador for prosthetic manual dexterity. Just to bring that question to the point.
Price definitely plays a role in prosthetics. So it is relevant to note that my current setup (Otto Bock parts, two MovoHook 2Grip 10A80 hooks, one System hand voluntary opening, cable controlled socket with rapid swap mechanism, all parts pimped for optimal performance) costs a mere fraction of a prosthesis featuring the iLimb by TouchBionics.
Comparison of the prices for terminal devices (iLimb hand wiothout prosthetics: around 50'000 CHF (not covered by insurance); Otto Bock system hand: about 800 CHF; Otto Bock hook: about 1'200 CHF - prosthetic arm with iLimb hand: around 78'000 CHF, prosthetic arm using body powered technology: around 6'000 CHF) shows that we are dealing with extreme differences in prosthetic cost.
Now, I like to be able to smoothly and without much technological overhead work through technical situations by wearing a contextually intelligent solution on my arm stump.That does not mean that I only and exclusively wear a hook? No!
- I like the constant and reliable availability of function (without recharging or additional weight) of the hook. Using it for cutting, grinding, working with aggressive solvents, the hook as many times proven technical advantage over any other replacement as all it takes is a scrub, disinfectant, ultrasound cleaning and we are back on track. At intervals, I get the silicon covers replaced but these are really cheap parts.
- I like to wear the Otto Bock system hand for certain situations and have that reliable too. And very good looking.
- Currently I am working on an art project as well.
As TouchBionics advertise the possibility to actually conduct a number of manipulations using their iLimb I found it relevant to offer a 1:1 comparison to this type of functionality. It may help to identify areas of improvement, it may help to adjust unrealistic expectations, and it may help to illustrate functionality. Images or pictures, videos or short films just provide a better illustration than mere words saying 'been there, done that'. - And then, most of these are situations that are just a bit harder to do with the amputation stump alone, they may take more time without prosthesis, or risk getting the stump injured.
Taking off wrist watch
I can remove my wrist watch using the stump or the hook but also using the Otto Bock Voluntary Opening System Hand. I am now wearing a Regal Prosthetics silicon glove that features great appearance and sturdy finger tips. Key to getting a wrist watch off fast is finding out how to best twiddle the lock. Here, I slide the plastic band through the lock and then pull a bit to get the lock pin out of the hole. Then I use an oblique pull trick for the wrist band to flip the pin over to the other side so it does not lock again (video: 0:10 to 0:15 seconds). All in all I get the wrist watch off in just under 20 seconds and that is in slow demo mode and with a mechanical prosthetic hand. Always remember: if you are after realistic looks, go for a good silicone glove (regardless of what you wear underneath); if you are after smooth, silent and immediate action, get cable control (regardless of the terminal device); if you need precise and full force grip or push/pull action, get a hook and if you want to look anthropomorphic get a mechanical hand.
"Bionic" prostheses Activities of Daily Living and Sports Brands Cooking Otto Bock Prosthetic hand Prosthetic hook Prosthetics Specifications and comparisons Touch Bionics iLimb Tricks and techniques Tricks with prosthesis