Saturday, April 29, 2006

The mechanical arm

Yesterday, I got my father a book for his birthday present.

The cashier at the bookshop was a young lady with a prosthetic left forearm and hand. It was quite a sight, the arm being coloured in olive drab (army green, one may say) and with a cable running the length of the arm and several metal supports for the cable. In place of 5 fingers, a wide aluminium clamp is used to grasp items. I reminded myself not to stare rudely at her prosthetic, thus I noticed that she had a neck length, densely curled dark blonde hair, grey irises in her eyes, a generally pretty face and a cheerful smile.

As I watched her go about processing the customer before me, I was quite fascinated with her comfort with her artificial hand.

While she was bagging my book, I ventured a question. "Excuse me, mind if I ask how you actuate that..." I trailed off, looking for a suitably concise phrase that would not be as dumb as 'fingers' (because it's a pair of pincers, not 5 fingers).

"Oh you mean how this works? Sure, I’ll show you in a minute," she replied, putting my father’s book in a brown paper bag.

She handed me the book, now wrapped in its brown paper bag. Flexing her pincers, she pointed out the cable that pulls them open. The cable runs to a metal scaffold protruding from the 'wrist', where it is then shrouded in a plastic tube very much like the coaxial brake cables found in bicycle brakes. The encased cable runs along the length of the forearm, where it is held by another metal structure near the 'elbow'. She pulled the sleeve of her blouse up a bit, revealing the more of the cable. The plastic shroud ends, and the bare cable is attached to a fabric sling of sorts that disappears up to her back.

By flexing certain muscles in her back, she can cause the contraction to pull on the cable, which in turn pulls the pincers open. Relaxing those muscles, the pincers close on their own accord by the action of springs.

"Impressive!" was all I could say. But then, show me the inner workings of a system and I’ll be impressed anyway.

"This hand is a simple one, but I quite like it," she continued, "the mechanical ones are too complicated with motors and the electrodes..."
I was lost. Isn’t this a already mechanical arm? A burst of clarity hit me- she actually meant 'motorised', which should be termed electro-mechanical, or at least electrical.
"The batteries too," I chime in, trying to act like I know the prosthetics trade from front to back. I mean, anterior to posterior.
"Yup. And sometimes they hurt, so I’ll be sticking to this one for a while. I’m happy with this," she said.

I thanked her for her time, and went on my way.

I do have a tinge of regret of not getting her to pose for a few portraits. I was actually worried she might be offended, but in hindsight, probably not. After all, she seemed very at ease with her prosthetic, and made no attempts to hide it. It was not in a long sleeve shirt. It was not skin coloured, but more like a slightly watered down shade of British Racing Green.

Damn it.

Next time, I must remember to ask myself,

What would Jesus ob!ique do?

End note:
Notice it did not even cross my mind to be curious about how and why the forearm had to be amputated?

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