Author Topic: Ideal upper limb prosthesis  (Read 1898 times)

Offline cogwollop

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Ideal upper limb prosthesis
« on: January 18, 2010, 11:42:46 AM »
Hi Everyone.

My names Jerome and i'm a final year design student in a small college in Ireland.

I'm trying to design an upper limb prostheses so i'm aiming towards problem solving. I'm wondering if anyone whould mind telling me what they would desire most in a prosthetic and what day to day problems people encounter in existing models etc.

The question is not just about function, but also wondering what people would like their prosthetics to look like.

I want to challenge the idea of 'disability' which i detest, but rater create something which is actually desirable..

Cheers! 
 

 

Offline Steve C

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Re: Ideal upper limb prosthesis
« Reply #1 on: January 19, 2010, 10:51:33 PM »
Jerome,

I'm a below knee amputee so of virtually no use to you as you're trying to design a upper limb prosthesis. That said, from a leg amputees point of view the things I need/want from a prosthesis are:
comfort
fit (it needs to fit perfectly. If it isn't perfect it causes discomfort)
having it secure (no moving about)
function (obvious)
low maintenance (usually from less parts or more durable parts)
light weight
low cost

As far as looks, I can go one of two ways. Very life like or no cosmetic cover at all. It seems that most prosthetics when exposed are very obvious especially where they are attached. Yet a very life like cover/skin will add weight which is bad. Get around this and you'll get peoples attention.

The reason people here may not post on this is because as amputees we run the risk of devotees or fetish freaks coming and posting on this forum. We want nothing to do with them at all. Or at least I don't. The reason I did post is because I put 'cogwollop' into google to see if I could see if you were 'legit'. I believe I found your website which seems to substantiate what you have said.

http://cogwollop.blogspot.com/

I hope I don't seem paranoid but we do want to steer clear of certain types. Anyway, I hope my post helps some. Good luck
Where ever I go, I'll always have one foot in Ireland   /   I'm not a complete fool. Some parts are missing.

Offline cogwollop

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Re: Ideal upper limb prosthesis
« Reply #2 on: January 20, 2010, 09:52:08 AM »

Offline Steve C

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Re: Ideal upper limb prosthesis
« Reply #3 on: January 20, 2010, 02:15:20 PM »
I tend to lump devotees and the fetish people into one. As per wikipedia:
"Acrotomophilia refers to sexual interest in amputees "

Some may come on the site to skulk around and some even pretend to be amputees. They get some sort of pervy gratification from it. Some go as far as to make themselves into amputees. Its mad but true. I'm sure there are many different kinds of devotees and fetish people from the somewhat interested to the obsessed to the dangerous.

I know Bantry but haven't been there for ages. West Cork is lovely. I'm from the states originally but have lived in Ireland 12 years now. I'm out in the wilds of Connemara.
Where ever I go, I'll always have one foot in Ireland   /   I'm not a complete fool. Some parts are missing.

Offline chrysochloridae

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Re: Ideal upper limb prosthesis
« Reply #4 on: January 20, 2010, 07:55:12 PM »
Hi Jerome

I'm a prosthetist in the UK and designing an ideal upper limb prosthetic limb is a real challenge.

With lower limb amputation, there is a limited number of activities that need to be carried out such as standing, walking and sports. With an upper limb prosthesis, it is a whole other ball game.

Firstly, it is important to understand what you use your arms for. As well as the obvious things such as lifting, carrying and writing; things such as Gesturing during a conversation, filling out clothes and cosmetic factors have to be considered.

With an upper limb amputation, alot of problems can be solved without a prosthetic limb. An excellent example of this is "How do you hammer a nail into a wall so you can hang a picture?"; you could use a high tech prosthetic device with a hammer attachment - or you could think outside the box and put a piece of blu-tack on the wall, push the nail into it and use your remaining arm to operate the hammer - this soloution is much easier and cost effective than the use of a prosthetic limb.

There are 3 main types of upper limb prosthetic
 1) Cosmetic
 2) Functional
 3) myoelectric

Cosmetic prostheses tend to look good but don't move very much so don't have alot of function http://www.ottobock.co.uk/cps/rde/xchg/ob_uk_en/hs.xsl/5058.html . Functional prosthesis tend to use devices to carry out specific tasks e.g. http://www.troppman.ca/ ; the most commonly used is a split hook (http://www.hosmer.com/products/hooks/index.html); split hooks arfe very useful as they facilitate most of the 6 differnt grips; but they don't look very cosmetic. MMyoelectric devices are a compromise between function  and cosmesis - you get a bit of both with a myoelectric device (but they are very expensive and have a tendancy to break down alot) - http://www.touchbionics.com/i-LIMB

All in all; there is no universal upper limb prosthetic that you can use for every patient - each prosthesis is prescribed to the needs of the individual. Some prefer a limb that is solely cosmetic and have no interest in devices such as a split hook; others aren't bothered what it looks like so long as it works!

The question you asked covers such a large area Jerome; i'd stuggle to answer comrehensively in 1 post!  I'd be happy to answer more specific questions as best as possible. i could also post some info to you if you need it (journals, text book articles and so on)


Offline cogwollop

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Re: Ideal upper limb prosthesis
« Reply #5 on: January 22, 2010, 07:52:31 AM »
Hi Chrysochloridae

Thanks for the links and info.

I've seen the I-limb before. It seems to be the top of the range myoelectric design, but it looks wickedly expensive. Also I've noticed that pronation and supination occours at the wrist rather than the elbow. I think this looks a bit odd. Expecially since it can rotate 360 degrees. I believe the thumb has to be rotated manually also.

I've noticed that most upperlimb prosthesis do not contain anything which replicates the movements of the metacarpals. Most contain rigid box structures acting as the palm with fingers closing directly downwards rather than in opposition with the thumb.

The body powered hosmer hook seems to be the old reliable. It is certainly simpler and cheaper and the few moving parts.

Do you know anything about neurologically controled prosthesis? I've seen Darpa's bionic hand project. It looks fairly unaffordable but the idea of linking the controls to a persons nerval system would certainly hasten their adaption to it.   

Check out the hydraulic shadow hand

www.shadowrobot.com

Unlike rigid mechanics, it moves compliantly with compressed air rather than breaking when placed in a position that it's environment rather than it's motor has decided. A great idea and has a huge range of movement but would require the user to carry a supply of compressed air!

I'm interested in designing a socket which extends from the body via a metal bar to create a greater sense of permanence with the prosthetic. I've seen something similar to this happen in external fixation. The difficulties I foresee are that a bar that crosses between internal and external provides no point for the skin to heal and the point of entry would likely require a constant application of saline to prevent infection. Do you know of any effective solutions? If so do you believe this type of structure could bear much weight or cause discomfort?

If you have any articles I'd love to read them. It quite difficult finding information on the subject.

Cheers

Jerome


Offline cogwollop

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Re: Ideal upper limb prosthesis
« Reply #6 on: January 30, 2010, 11:43:04 AM »
Osteo-integration was the word i was looking for!

Thanks anyway

Good luck