As I take an interest in what function of a prosthetic terminal device such as a hand is useful, I also take an interest in things I do not need it for. For various reasons. My skin needs to recover and I cannot wear the arm all the time. Also I am interested in what grips do and what grips do not represent a “benchmark” grip that is useful to compare prosthetic devices such as hands against each other.

So when I read the statement “I can do [X] with the prosthesis” I immediately tend to go “wow!” – but on second thought I ask myself, well, was that really necessary? Was it necessary to even put the arm on in the first place? Can I do [X] also without the prosthesis? Or get it done differently?

Obviously some advertising of the Smart Hand project says that the Smart Hand would cover at least 80% of the grips contained in ADL (activities of daily living) – but I already solve a lot of grip situations for ADL without any prosthesis, not elegantly maybe, but I’ll be getting there. So what does “I can do [X] with the prosthesis” tell us really? What does it tell us about the understanding the creators of advanced prosthetics have: where is that detailed analysis that they base their work on?

So I started to pay closer attention. And I figured out that a number of things that I do require not much of a prosthesis. Some prostheses are presented as particularly useful because you can put a tie on, open a bottle, et cetera. But in reality these are Activities of No Particular Prosthetic Need (ANPPN). So these activities are not very useful to show the use of a prosthesis.

A typical example that can be encountered at times is that of putting on a tie. Yes, given the correct setup it is possible to knot a tie with a prosthetic arm. But I can put that tie on just as well without the prosthesis.

Dependence: Obviously, not all ADL (activities of daily living) are dependent on wearing a prosthesis. So, if someone wearing a prosthesis tells you, look, I can put on a tie – you are being shown something that prosthesis may not even be necessary for. Then you are being had.

Support: Even though I may not depend on a prosthesis for a particular act, I may still benefit from its support. So, what is the support, what exactly does support mean? What does support spell out as? It can mean to be able to type in a more balanced way and avoid shoulder, elbow and wrist problems – but then we need to evaluate shoulders, elbow and wrist to evaluate that claim.

Compare
A high-tech iLimb with finger extended does not at all appear to be relaxing for shoulder and elbow as for each type, shoulder abduction and elbow elevation are required to move prosthetic index finger into position:

In comparison, a body powered hook or using a pen in conjunction with a prosthetic hand can be far more natural for body posture when typing:

The term ‘support’ can also mean to put non-disabled people at ease by its appearance – but then, the focus of our consideration must be on these people (and not on some product macro photograph). It can be that a prosthetic hand allows me to drive far more comfortably – but then, why is driving otherwise a problem, and in what way does the prosthesis help? Only by providing a close-up under the hood optic will we approach the subject of how ADL, ABNPPN and prosthetic evaluation really relate.

Switching: As we know, different terminal devices necessitate a quick release wrist. And ANPPN or even ABDWP (Actions Best Done Without Prosthesis) constitute a requirement to allow for a convenient removal of the prosthetic arm. Currently, my main ABDWP is swimming, and as I undress anyway, taking a body powered arm off is not an issue.

So, this is just a list of illustrative tasks, not meant to be comprehensive.

There is getting dressed, brushing teeth, shaving, taking a shower, handling bottles and drink cartons, shopping, vacuuming, and many other things to be listed here. I *can* do them with a prosthesis, but also without one.

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Open milk carton

That works the same way for other stuff. Yes I can open it with the prosthesis. But I can just as well do it without.

Put on tie

Put on and take off wrist watch

Putting on and taking off wrist watch is not too hard even without a sophisticated prosthesis. In fact it is a lot easier without artificial arm. I mean, I tried. I know.

Same procedure with prosthetic hand:

Tying shoe laces

Typing