A One Handed Blog

I picked up my final socket for my i-Limb hand a week back, from Rich at Diablo O&P . He had lovingly created a carbon fiber socket with a blue fleck running through it based on the test socket he had made earlier.

We decided to move the electrodes up higher to try and resolve the issue, where, previously the holes in the liner were too low and let air in and so didn’t keep the socket secure on my stump. It was a bit tricky trying to work out where the holes should be cut in the liner (the liner costs $500 a pop, so don’t want to make a mistake), but we guesstimated as best we could and it seems to be working for now!

I’m starting to wear my new arm a little at a time, I have pretty good control of opening and closing the hand, although rotation is going to require a bit more work to master. It’s amazing how easy it is to control, I just contract the muscles I would normally use to open/close my hand, just in a more exaggerated motion. Rich did a great job creating the socket and dealing with the bulky battery. If I wear a long sleeved top you really don’t notice it, the length and angle of the socket is perfect…I bet you’d probably not even notice my hand wasn’t real at first glance!

The socket is a little lighter than my test socket, but the overall prosthesis still weighs just under 3lbs, which will take a bit of getting use to. Also, the weight of the hand causes the socket to move around a little on my stump, since it isn’t secured above my elbow as would normally be the case for this type of device. This caused a blister the other day where the electrode touches the skin on one side…so still some teething issues to iron out.

Last week I picked up my test socket from Rich, at Diablo Prosthetics & Orthotics, fitted with the i-Limb hand. Since this is my first myo-electric hand we are still experimenting with the socket design and electrode placement, so it’s still early days.

The test socket Rich built is pretty cool, it’s clear plastic so you can see all of the wires and motor inside (the final socket will be carbon fiber). As well as the i-Limb hand we’re trying out an Otto Bock wrist rotator unit as well, this allows me to rotate the hand 360 degrees (that should freak people out over Halloween).

The socket has two electrodes inside that are in touch with my skin, these pick up the electrical activity when I contract my muscles. If I contract one muscle the hand opens, if I contract the other the hand closes. The speed of the hand is proportional to how hard I contract the muscle. If I contract both at the same time the wrist rotates instead, depending on which one I contract the hardest, the wrist rotates one way or the other…this will take a bit of practice as you can imagine!

The fingers/thumb on the hand are independently driven, each has it’s own motor. Sensors feedback the force exerted by each finger so, although my control is limited to opening/closing the hand, each finger moves independently allowing the hand to grasp irregular shaped objects. I can also rotate the thumb manually from the side of the hand to over the palm, thus changing the grip pattern from making a fist to grasping a bar, for example.

The whole thing is pretty heavy, at least to what I’ve been use to. It weighs 3lbs in total, about half is the hand and the other is the socket. Next week I’m going back to see Rich to change the position of the electrodes and see if we can get a better fit with the socket and liner. We’re trying to use a liner with a lock pin, as per my current arm. The challenge is we have to cut holes in the liner for the electrodes, this reduces the ability for the liner to keep the socket snug on my stump…this is an unusual approach for a myo arm, but if we can get it to work the benefit is the socket doesn’t restrict my elbow movement.

TouchBionics have now released their i-Limb hand commercially in the US. I have written about it a couple of times and it’s an amazing device…check out their site for some action videos of people using it.

There are also some videos on YouTube, check this out out…watch closely and you’ll see the world’s first bionic ‘flip off’:

Of course, now I want one!

Since the hand is myoelectrically controlled I need to get fitted for a myoelectric socket that has the sensors to pick up the muscle activity (electrical signals) in my arm. The first step was to get tested to see if I am a candidate for this type of arm.

So I went to see Rich again at Diablo Prosthetics. He used a myoelectric testing unit to see if I have sufficient muscle activity. There are two electrodes that are put in contact with the skin over different muscles. I then have to contract each muscle independently and the device measures the strength of the electrical signal.

Fortunately it looks like I have more than sufficient output and with practice I should be able to isolate each muscle so I can contract them independently.

So the next stage is to start the process of getting fitted for a myoelectric socket. I’ve been in touch with the guys at TouchBionics and I’m excited to be working with them to get fitted for an i-Limb hand. Not quite Luke Skywalker but definitely a step in the right direction.

I got my new arm this week, a thing of beauty! Rich Sire from Diablo Prosthetics did a great job on my new arm, I wanted to go for the high-tech look since I didn’t really like the look of my first prosthetic, which is pink (looks like a dolls arm). Since I’m not trying to pretend I have a real arm I might as well go with something that looks sleak and stylish!

My new carbon fiber socket is lighter weight and more streamlined than my old one, since my stump has shrunk about an inch in diameter and taken on a much less bulbous shape.

We’ve also used a different suspension system this time, a more traditional locking pin. The new liner I have is thinner, which also helps reduce the size of the socket and with the pin at the end of the liner locked in, it ain’t going nowhere (unlike my old socket which kept coming off).

Rich took some photos as he was making the socket, as before it starts of with the plaster cast made from the initial test socket. He attaches the locking mechanism to the end and a clear plastic inner liner. He then uses bees wax to mold the wrist section of the prosthesis, this is later melted away to leave it hollow.
Next comes the carbon fiber that is attached to the wrist and rolled down over the socket ready to be impregnated with resin.

It’s been about 10 months since I was fitted for my prosthetic and my stump has shrunk about an inch in diameter, as you can see from the photos (I took the first back in August last year). This means my prosthetic is now a little lose, to say the least…it’s a bit embarrassing having your arm keep dropping off as you walk along…I have to keep pushing it back on since otherwise the suction slowly gives way and off it pops!

So it’s back to the shop for a new arm. I used to be with Hanger, but, Rich Sire, who I worked with has since left and started his own company, Diablo Prosthetics and Orthotics. I really liked the way Rich worked with me and was willing to try things to meet my needs so I stayed with him and of course wanted to help support a new business. So now it’s take two as I get fitted for a new socket.

Based on my experiences with the suction based suspension system with my current socket and liner Rich has been looking for a different solution that might work better for me. The the suction system makes it easy to take my socket on or off, but, it doesn’t hold when I’m in the gym and slowly releases over time. This type of solution probably works better for lower limb prosthetics where there is constant body weight pushing into the socket, the problem with upper limbs is the socket is always weighing down and over time the suction just seems to give way…so I can’t say I’d recommend this for anyone.

This time we’re going to try an Otto Block Silicon ArmLiner, this uses a lock pin in the end of the liner to lock into the socket…so no problems with it dropping off. It also has the added benefit that it’s much thinner than my current liner, so shouldn’t restrict my elbow movement as much and hopefully will result in a more streamlined socket.

Also this time around I’m going for a carbon fiber, high-tech look. I didn’t really know what to expect last time and so opted for a ‘pink’ coloring to be added to my socket, quite frankly the color looks like a dolls arm. Since I’m really not worried about the cosmetic look of my prosthetic (I’m not looking for something that looks like a real arm) I plan to go for something that looks more sporty this time! This has the added benefit that the socket can be thinner and more streamlined and of cause lighter weight.

I’ll share some pictures with you once I get it, it’ll probably take a couple of weeks to get it made and fitted.

I still haven’t got my prosthetic hand yet, it’s been a challenge for Richard at Hanger to get a test socket to fit. My stump is a bit bulbous, which, as you can imagine, makes it a challenge to get a socket to go over the bulge in the middle yet still fit snuggly to the stump.

It was third time lucky last week though, Richard successfully created a socket that fitted well. Now he will turn this test socket into a real one made from carbon fiber and then I can start experimenting with the hand attachments to see how they work for me, I’m quite excited to finally get to try something out and see what difference it makes.

Richard kindly took some photos of the process of making the test socket. The first one on the left is the initial mould taken from the cast he made of my arm, it’s pretty rough and has to be sanded down and smoothed out before they can make the socket from it. As you can see they just use a normal file to get rid of the imperfections and to reduce the size of the mould by 3-5%…this is where the skill comes in to reduce the size but not to make it too small that the resulting socket won’t fit. In my case, for the third test, Richard didn’t reduce the size of the mould at all, instead, when he took the cast of my arm he shaped the tissue in my arm while it set.

In this next shot you see them heating the plastic sheet ready to make the socket, notice how it’s bowing down. Then they shape the sheet around the mould and finally apply the vacuum to suck all the air out and create the final result.