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Category: Socket/liner

What to do once your arm has mindboggling amounts of DOF but your stump can only address 2-3 ? [tech scifi stuff]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - What to do once your arm has mindboggling amounts of DOF but your stump can only address 2-3 ? [tech scifi stuff]; published March 8, 2016, 19:08; URL: https://www.swisswuff.ch/tech/?p=5779.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - What to do once your arm has mindboggling amounts of DOF but your stump can only address 2-3 ? [tech scifi stuff]}}, month = {March},year = {2016}, url = {https://www.swisswuff.ch/tech/?p=5779}}


Currently, media are swamped with the display of what they call "phantom limb project" (really not the first time that someone uses "phantom" for a prosthetic arm; read about my Becker Phantom hand from 3 years ago right here). So apparently, some prosthetic technician spent major amounts of time trying to construct this computer game look-a-like arm to a degree where its user apparently considers that he is a cyborg with an additional "cyborg mother", as if prosthetic parts have parents, too. Yeah, and my website also has a "cyborg father". If you listen for him, you might hear him breathe, "...khhhhh-ccccchhhhhhhhh-khhhhhhh-czzzzzh...".

dvader

Where is Amber Case, when we need her.

Now, while that Metal Gear inspired prosthetic arm design worn by James Young certainly does not look like it is going to wreck major brick walls any time soon, they might explore entirely different aspects of such equipment.

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Body powered arms [technical design overview]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Body powered arms [technical design overview]; published November 21, 2013, 07:05; URL: https://www.swisswuff.ch/tech/?p=2371.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Body powered arms [technical design overview]}}, month = {November},year = {2013}, url = {https://www.swisswuff.ch/tech/?p=2371}}


Body powered arms are not the same. Despite everyone saying they understand what these are, these arms are not the same.

My setup explained, a generic setup explained. To show similarities and differences. For those in need to learn about this, technical differences to myoelectric arms are explained.

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WillowWood Alphaliner silicone defect [photos]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - WillowWood Alphaliner silicone defect [photos]; published September 24, 2012, 06:57; URL: https://www.swisswuff.ch/tech/?p=881.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - WillowWood Alphaliner silicone defect [photos]}}, month = {September},year = {2012}, url = {https://www.swisswuff.ch/tech/?p=881}}


WillowWood Alphaliner with unusual defect.

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Below elbow amputee socket with guitar plectrum mount [proof of concept]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Below elbow amputee socket with guitar plectrum mount [proof of concept]; published August 31, 2012, 06:19; URL: https://www.swisswuff.ch/tech/?p=810.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Below elbow amputee socket with guitar plectrum mount [proof of concept]}}, month = {August},year = {2012}, url = {https://www.swisswuff.ch/tech/?p=810}}


Carsten Werner from Köln (Germany) - also a right below elbow amputee - allowed me to web publish his design and implementation for a plectrum mount. With that, he passed the entry test for a Jazz College back in 1988. And with all due respect for other one handed guitar players, that is an achievement I find hard to match.

The design contains a round piece of metal with one part bent up straight. Against that, a metal bar is squeezed with two screws. The rest - semi circular slit for rotationally variant mounting - is self evident from the photographs. In terms of positioning on the socket, it appears to be necessary to place the plectrum close to the end of the radius bone - or wherever else you feel most comfortable.

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KISS Technologies LLC - new liner-socket interface [preview]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - KISS Technologies LLC - new liner-socket interface [preview]; published March 28, 2012, 23:18; URL: https://www.swisswuff.ch/tech/?p=542.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - KISS Technologies LLC - new liner-socket interface [preview]}}, month = {March},year = {2012}, url = {https://www.swisswuff.ch/tech/?p=542}}


Smart phone built into prosthetic arm [tech]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Smart phone built into prosthetic arm [tech]; published November 20, 2011, 16:28; URL: https://www.swisswuff.ch/tech/?p=509.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Smart phone built into prosthetic arm [tech]}}, month = {November},year = {2011}, url = {https://www.swisswuff.ch/tech/?p=509}}


Another mostly useless prosthetic arm suggestion is made available by ever so countless online news services.

If only one of these ever tried to read and understand what things are about.

Alright, so here is the blurb:

According to The Telegraph, Trevor Prideaux has become perhaps the first man with a built in smartphone. Prideaux was born without a left arm, and had to go to extra lengths to use his cell phone.
Thanks to help from Nokia and medical experts in Great Britain, Prideaux now has a Nokia C7 embedded in his prosthetic arm, which makes texting and calling his friends and family infinitely easier. Prideaux says this about the medical marvel:I think this is the first time this has ever been done in the world – and it is brilliant. Seeing medical technology merge with communications is extremely exciting, as we’ve seen amazing life-changing stories in the past thanks to technology achievements and creativity.

Oy vey. As ever so often there are two relevant bits missing here:

  • Point 1: He is not the first person to carry entertainment technology as part of his prosthetic arm. Maybe in Great Britain but certainly not world wide.
  • Point 2: Secondly, the thing won't be nearly as much fun as it appears if ever the journalists would have paid attention instead of providing literally blind copies of this. Just shows how little journalists know about stuff these days. In short - there is something missing that is very important in this context.

Let's have a look, shall we.

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Elektrische Prothesenheizung [Montageanleitung]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Elektrische Prothesenheizung [Montageanleitung]; published December 27, 2010, 05:21; URL: https://www.swisswuff.ch/tech/?p=379.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Elektrische Prothesenheizung [Montageanleitung]}}, month = {December},year = {2010}, url = {https://www.swisswuff.ch/tech/?p=379}}


Aufgrund meiner persönlichen Befindlichkeit habe ich mir eine elektrische Prothesenheizung gemacht.

Hier auf Deutsch nur die Montageanleitung, den vollständigen englischen Artikel mit Hintergrund, nicht verwendeten Heiz-Alternativen, usw. finden Sie hier.

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Electric heating for my prosthetic arm [tech build / instructions]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Electric heating for my prosthetic arm [tech build / instructions]; published December 27, 2010, 01:43; URL: https://www.swisswuff.ch/tech/?p=378.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Electric heating for my prosthetic arm [tech build / instructions]}}, month = {December},year = {2010}, url = {https://www.swisswuff.ch/tech/?p=378}}


2 Comments

I am suffering from the combination of cold and bad circulation in my stump. It causes a blend of stump pain, an increase in phantom sensation and ultimately phantom limb pain [6].

To specialists, this is a well known issue and not a rare problem; particularly, venous drainage problems have been documented to correlate with stump and phantom pains [1]. Vascular return is particularly a problem with longer forearm stumps [2,3], and in my instance, that issue was known and declared to me even before the amputation by the surgeon, however, having a long stump has a lot of advantages as well. Compressing the stump helps to decrease the cross section of my arm veins as all cutaneous veins are compressed and thus pressure is higher in the deeper veins - a well established observation also for legs, where a certain well balanced venous compression (but not too much of it) has been documented to increase flow [4,5 - see text cited with these references below for details about pressure]. What treats the congestion well is a relatively tight fit of a prosthetic socket, or a tight compression sock, or a tight bandage. I wouldn't just say snug, I'd really need it tight - but not too tight [6].

To make things worse, a vicious cycle seems to occur at the moment my poorly circulated stump is cooled down significantly. Then, circulation gets minimal rather quickly and pains of stump and phantom hand get severe and hard to bear. Normally, phantom sensations and pains as they occur daily are no big issue - one does get used to these. But that type of extreme pain is a warning signal. So I decided to take that signal serious and after getting what they call 'minor frostbite' on my stump from a skiing weekend, I went forward to research the issue of heating the prosthetic arm externally and to build such a heating from available parts. For my condition - bad venous drainage, bad vascular return, cold vicious cycle - a moderate but steady heating that would fit inside the prosthetic arm and that would last for a steady few hours and not peak over only minutes was what I needed.

Now seeing as if that is a really medical application, why not say one word about that. My arm stump has a reduced ability to sense temperature. That means if the darned thing gets too hot, there is a really good chance I will only know once it is too late. Logically I will opt for a less aggressive heating, and exclude heat pads (see below). As I am doing this completely cross label, using parts that were not designed for this application, I am doing this the usual test pilot way - test extensively, check extensively, but take a certain risk as well. If anyone was to sell such pads for prostheses you will have to get really good insurance, as stumps and prostheses in winter are a really complicated subject you may just not want to get into. This is for people that are in the position to try it out themselves and take any consequences necessary at any given point in time.

So, here we go.

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Socket length for long forearm stumps - extreme back-to-back mount of Ossur Icelock pin-lock and wrist

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Socket length for long forearm stumps - extreme back-to-back mount of Ossur Icelock pin-lock and wrist; published June 13, 2010, 17:44; URL: https://www.swisswuff.ch/tech/?p=319.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Socket length for long forearm stumps - extreme back-to-back mount of Ossur Icelock pin-lock and wrist}}, month = {June},year = {2010}, url = {https://www.swisswuff.ch/tech/?p=319}}


This is invasive works.

To get my long stump (~6cm behind wrist) to still allow for correct socket length, and to allow usage of regular components, we did some things.

My wrist (see series description) has a central bore (image below, left). This is necessary to allow for the pin to protrude through the pin lock (hole, image below, right) into the wrist space.

My socket (image below, right) contains an Ossur Icelock. As I figured out, its distal metal plate (round shiny plate) is quite thick and so lots of that material can be milled down without problems. The lock still works perfectly well.

So if it is necessary to achieve a correct length (not an over length) for long below elbow stumps, grinding down parts and keeping at it is the way to go. This is what I did to my socket that was 2-3cm too long: as proof of concept, I reduced the length dramatically and took the resulting shortened socket to the prosthetic technician to clean up. Now I have two perfectly measured sockets.

Looking at the cross section of the end of my shop-issued socket (diagram, left), the wrist (w) sits on top of some epoxy (e) that constitutes the end of the socket and holds the pin lock (pl) in place.

I removed a lot of bulk (diagram, middle, "remove") and milled down into the metal plate of the in lock (pl) to gain another 3-5 mm. Even the plastic unlock button does not require a full casing, that can be partly removed as well.

The result (diagram, right) is an extremely tight construction that only works if the wrist has a central bore.

Disclaimer: I knew what I was doing. If you don't get it right, you risk damaging possibly expensive parts. So you are definitely on your own with this.

Socket control of pronation and supination [demo]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Socket control of pronation and supination [demo]; published June 13, 2010, 17:00; URL: https://www.swisswuff.ch/tech/?p=315.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Socket control of pronation and supination [demo]}}, month = {June},year = {2010}, url = {https://www.swisswuff.ch/tech/?p=315}}


My forearm stump allowed only very limited pronation and supination until three months ago.

As it appears, there are some 'technical promises' around that include a promise for better pronation and supination as part of their promised betterments:

  • Osseointegration
  • High-fidelity sockets

I found that just for good pronation or supination, neither seems to be necessary. In fact, all that had happened was that I shrank and as a consequence, my previous sockets had become both rather wide and loose.

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How to make a prosthetic socket [myth buster]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - How to make a prosthetic socket [myth buster]; published February 24, 2010, 15:07; URL: https://www.swisswuff.ch/tech/?p=289.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - How to make a prosthetic socket [myth buster]}}, month = {February},year = {2010}, url = {https://www.swisswuff.ch/tech/?p=289}}


It has been alleged by proponents of osseointegration that prosthetic socket making was a black art that orthopedic superconglomerates used in a conspiracy to make amputees dependent of stump sockets (commonly looked down upon as 'buckets') and ultimately suppress and exploit amputees - whereas osseointegration (getting a bolt put in the stump) would free amputees of any such dependency.

We have seen the words 'bucket sob' to refer to sweat accumulated in sockets - all nice and sweet but that opens up a whole new domain of dialog. If such words are used then I'd call the comprehensive lifestyle restrictions of osseointegrated people 'bolt fright'. Not wearing a normal weight prosthetic arm out of 'bolt fright'? Not coming to the public swimming pool out of 'bolt fright'? I mean, I do understand a little bit - with little children, old people and all of their bladder incontinence, the water may not always be super pristine...

Obviously, osseointegration - putting metal bolts into the bone stump(s) and have these stick out through the skin to attach a prosthesis to - makes you not at all 'less dependent'. At best osseointegration may help shift your dependency to a zone where you (but not necessarily others) may hopefully feel more comfortable - but whether that will be the case depends on your individual comfort zones, your ability to comply with the upkeep and cleanliness, and other factors including luck. Osseointegration also has specific risks and costs - for example, one bolt to be put into an arm costs around ~ 80'000 US$. Furthermore, osseointegration will make certain things outright impossible (as a formerly soft stump end now will permanently have an edgy protruding metal and you can never softly touch anyone any longer) and it will make other things difficult (as infection and mechanical breakage may quickly cause complications of a more serious nature).

So this moment, the original assumption - that the orthopedic establishment is using sockets as black art to make amputees dependent - requires some in depth myth busting.

Actually, anyone can build prosthetic sockets.

How to make a good prosthetic socket is something anyone who builds model airplanes, anyone who can buy do-it-yourself goods and anyone who has some time can easily tinker with and do. Besides, any normal prosthetic technician will interestedly accept self-built constructions that you show them, and learn from them. In my experience they never looked down on or laughed at a self-built or modified solution but instead tried to understand distinct advantages and later maybe implement them. Also they will happily use better components if they know where to get them and what to do with them, any time.

No conspiracy from where I'm standing.

Sockets come at relatively expensive prices maybe, but no conspiracy. And comparing a 3'500 US$ socket against an 80'000$ bolt that associates with a myriad of risks and complications, my bet is that sockets feel great and have good stability if they are built from modern materials by people that know what they are doing.

How to make sockets? Here's how.

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Dan Horkey takes prosthetic socket artwork to *CHROME*

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Dan Horkey takes prosthetic socket artwork to *CHROME*; published October 14, 2009, 22:52; URL: https://www.swisswuff.ch/tech/?p=227.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Dan Horkey takes prosthetic socket artwork to *CHROME*}}, month = {October},year = {2009}, url = {https://www.swisswuff.ch/tech/?p=227}}


Dan Horkey of Global Tattoo Orthotic Prosthetic Innovations (GTOPI) has taken prosthetic socket coolness to the ultimate - chrome! He is testing the new chrome finish and hopes to make it available soon so you can now get yours fully chromed.

This is way cooler than anything there was before. It goes way beyond my beloved chromed cuckoo clock art project. It is so real you could probably use it as shaving mirror.

This one is the real deal:

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Schweiss und Hautprobleme am Stumpf - Stumpfpflege

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Schweiss und Hautprobleme am Stumpf - Stumpfpflege; published August 10, 2008, 17:47; URL: https://www.swisswuff.ch/tech/?p=230.

BibTeX: @MISC{schweitzer_wolf_1573561281, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Schweiss und Hautprobleme am Stumpf - Stumpfpflege}}, month = {August},year = {2008}, url = {https://www.swisswuff.ch/tech/?p=230}}


Schweiss und warm-feuchtes Milieu unter dem Silikon-Liner fuehren dazu, dass die Haut an meinem Stumpf gelegentlich gereizt wird, zunaechst leicht zu jucken beginnt und dann ein roter typischer Ausschlag entsteht, der einem Windelausschlag bei Babys aehnlich ist. Stumpf- und Materialpflege ist hier Schluessel zur Reduktion dieser Probleme. Ausserdem sollte man sich mit der Frage der Warmwasserqualitaet beschaeftigen. Read More

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