The question is: Why do people stop using their prosthetic arms? This question is relevant as:
- Arm amputees are a rare occurrence, relatively. Due to that, non-disabled people will feel nervous and start by supplementing real dialog with self-constructed ideas. That is the beginning of a usually somewhat bad ending. But it is very much going on.
- Prosthetic arms seem to be very expensive, probably also as a consequence of that.
- And studies show at least 30% of arm amputees not using their prosthetic arms anymore; adding to that the people that don't even participate in these studies anymore, an anecdotic observation of around 50-70% of non-users seems far more probable.
So in an under-serviced market, companies may run up to a rare form to sell cheap electronics for dream prices that further that vicious cycle or death cycle. Academic research "then comes to the rescue" by making things a lot worse. then, one escalates everything by making things just a tad bit worse - adding features, making it less useful, et cetera - just to start over again. That, in one term, is a vicious cycle.
Isn't this absolutely remarkable (after all, you read it here first)?
-> 1. Prosthetic arm:
- looks cool, but ...
- horrendously expensive
- painful, bad fit
- not very useful
-> 2. As a direct consequence, a certain percentage of amputees stop wearing their arms because of:
- not reliable
- cannot finance the repair or new arm
- very limited usefulness
- shoulder, nerve, stump problems..
-> 3. Logically, the situation deteriorates:
- an already tiny market shrinks more
- arm amputees are to about 50% (but, more realistically, over 85%) defined by living without a prosthetic arm
-> 4. Non-disabled people feel bad about this and decide the following:
- let us put more features on the arm
- (more features require more blech)
- let us make the control a lot more complex
- let us make it look like a hand
- dont worry about the socket
- let us fiddle with it in the laboratory
- let us use parts or components that work well in the laboratory but have practical problems (myoelectrics: serious problems with sweat, fatigued muscles or cold ambient temperatures; hydraulics: oil leaks, air leaks; accelerometers: difficult read-out in real-life situations; invasive things: require surgery and that is always risky and expensive; ..)
-> 5. Logical consequences:
- features, stuff, blech > weight goes up even further OR function goes down even more
- too complex > unreliable [link], fragile [link]
- no hard field testing > overall useless for everyday tasks [link]
- ignoring socket > bad fit, worse fit [suffering a current "bionic" arm: link]
- shrinking customer base > prices go up further
- parts that are unfit for real life > failure, frustration on the user end
-> back to 1.
Breaking the cycle
The vicious circle can be broken if the other party is not completely unwilling or unable to communicate or overcome existing stereotypes:
Non-disabled people could do the following but may be unable (due to listed reasons):
- listen to amputees (not possible due to stereotypes about amputees)
- reduce unnecessary overhead (but more is better, innit?)
- make the control a lot easier (how can simple ever be good)
- make it functional by all means (but a totally complex hand is what everyone wants, right)
- care about the sockets (stumps, eczema, sweat, scars, bruises is their problem not mine)
- hard real-life testing (but, i want tests where my complex heavy hand product comes out on top so let us ease up on that one)
- build it so it is long lasting, cheap and good quality (how are we gonna ream the insurances then?
Arm amputees should do the following but may be unable (due to listed reasons):
- keep insisting to make my voice heard (but: difficult due to stereotypes about non-disabled)
- coerce technicians to go lightweight and a simple arm (but: more is better, innit?)
- insist on simple robust control (how can simple ever be good)
- make it functional first (but a gadget hand is what everyone expects me to wear, right)
- keep insisting about the sockets (but when i wear no prosthesis my stump is just fine)
- practice use a lot (but then my stump gets bruised and the prosthetic breaks and then what)
- build it so it is long-lasting and of good quality (frequent visits to the technician are entertainment)
- let me find out what i want (not what the others want) (that can be hard without support or lobby)
This blog, most obviously, is an attempt to make my voice heard and to promote sensible, well-founded problem-solving for prosthetic solutions or other issues related to below elbow amputation.
If reading, listening and understanding is not your thing, then all words are wasted anyway. And if reading, listening and understanding in fact is your thing, I guess we will invariably know it anytime soon.
And exceptions to the above-listed well-established standard behavior are, well, exceptions.
Breaking this vicious cycle can also be hard or impossible as two existential or philosophical issues may be in the way:
- technical facts are not known
- how views about reality are handled
- what reality is for a given person
- downrated social status of amputees
Update 2018 - we recently wrote up the experiences with comparison and tweakings, of both body powered and myoelectric technology. That will also help shed light into the vicious cycle aspects of prosthetic arm technology. Check here: publication [link]
Update 2018 - See Quora entry [link]
Myoelectric control error rates did not improve over 40 years of research [link]
Several academic researchers have verbally confirmed this vicious cycle to be a valid observation.
 McFarland L et al. (2010) Unilateral upper-limb loss: Satisfaction and prosthetic-device use in veterans and servicemembers from Vietnam and OIF/OEF conflicts. Journal of Rehabilitation Research & Development.