I previously went into detail of the requirements for prosthetic arms to reduce overuse and strain [link].

Now, again.

From that, I would say it is quite clear that the following does constitute a problem:

• chronic overuse is a term that refers to damage inflicted by wrong or too intense activities
• it typically affects the non-disabled arm, not the disabled arm, of unilateral below elbow amputees
• so in other words, the disabled arm is NOT the arm that typically gets overused and
• that is, mostly if not always, the consequence of prosthetic arms that are built wrong, more precisely
• they are too heavy and their center of gravity is too far at the end of the arm, while the socket does not work well and the hand does not hold up

In a normal response to these requirements,

• non-disabled engineers show a great capacity and ingenuity to not understand that but instead
• follow the pre-defined path of the death cycle [link] of prosthetic arms in order to further achieve these two goals:
• 1) increase revenue for feature over-loaded prosthetic arms and
• 2) increase weight, and, decrease function, of prosthetic arms in face of actual activities that actually risk to overuse the non-disabled (!) (did you now read that closely? I said: non-disabled arm!!) arm.

Again, now, researchers are cited with such sentences:

There is limited documented data on prosthetic use, Miguelez says. “We want to study the amount of compensatory body movement required by multiarticulating hands compared to traditional prosthetic hands. A hand that decreases compensatory movement in the wrist, elbow, and shoulder should decrease the possibility of injury and increase a patient’s function and time spent using the prosthesis, which should provide a better functional outcome.” From: Hand Across the Ocean, by Kate Hawthorne, The O&P Edge, January 2013 edition [link]

This is quoted to come from John Miguelez of Advanced Arm Dynamics.

Here are the facts about this:

• It is not relevant what compensatory movement I make for anything. What matters is whether I end up with overuse. If I reliably wreck the multi-articulating hand while vacuum cleaning, or, if I put too much weight on my shoulders and elbows while I hang laundry, then the problem cannot be captured by compensatory motion capture.
• My trunk muscles – back, belly, legs, chest – rarely if ever end up overused. What gets overused is the non-disabled arm’s small joints such as elbow, wrist, shoulder and so on – not the disabled arm’s joints as suggested by Miguelez.

I suspect that their newly installed think-tank group “SCULPT” (Strategic Consortium for Upper-Limb Prosthetic Technologies) may not be after actually evaluating technologies to reduce upper extremity amputee’s overuse problems at all. My suspicion is that they will target the problem that they do not sell nearly as much massively expensive multi-articulated prosthetic hands as they would like, seeing as if these have prices 5-10 times as high as the less easy to build and maintain body powered arms. That is what I suspect is their actual goal simply because in any real world, and assuming overuse of remaining non disabled arms actually was an issue, Miguelez’ statement above would make no sense whatsoever.

So, to help investors and insurances that REALLY are interested in overuse issues along here (you are still aware of the name of this blog, right? it is you that navigated here, right?):

• IT HAS ALL BEEN SAID BEFORE [link]
• prosthetic arms need to be very light (forget myo arms)
• prosthetic arms need to be very robust (forget myo arms)
• sockets must not restrict elbow movement (forget myo arm sockets)
• cable control must be ultra tight and ultra precise (forget conventional body powered arms)
• cable harness must not damage the other shoulder’s nerves including the brachial plexus (no one said building a good body powered arms was easy)
• components must be very sturdy and built and designed for wreckage (not myo arms)

Other than that I am really interested in seeing what type of recommendation SCULPT comes up next.