The latest prosthetics can now be controlled intuitively, by the mind, through a process called targeted muscle reinnervation (TMR). We spoke with Corporal Andrew Garthwaite who was injured by a rocket-propelled grenade while serving in the Nadi Ali area of Helmand Province, to find out how it all works.
From Able Magazine #110 (March/April 2014)
How did you come to be involved with Ottobock?
During my time at Headley Court (rehabilitation unit), Professor Asman came to do a brief on TMR and I was invited to come along. It all looked very futuristic but at the end of the presentation he wanted to see me and said he would like to work on me first. So three months later I was under the knife.
Why was the decision taken to use this particular prosthetic?
I think the main reason to use this prosthetic was that all of the parts for the arm are off-the-peg so my transition from military care to NHS would be easier and the NHS could order (new) parts if needed, with ease.
Did you have any influence over the way the prosthetic performs? Did you have any specific notions about what it must be able to do?
I was told what the arm would do and I did see videos. I used a myoelectric arm previously and it does exactly the same as that but a lot quicker – and I can now do three motions at once instead of one at a time.
Did it take practice to learn how to use it?
I was in rehabilitation after the operation for two years where an occupational therapist a prosthetist and myself, worked together. Each movement came gradually and we had to work on this to improve muscle strength etc. It was a very long process.
Are there any differences between the prosthetic and your hand (apart from the sense of touch) that are problematic? Is it too weak or too strong, etc?
In terms of a prosthetic to the real thing that is a hard question, as nothing will ever be as good as your real hand, but the prosthetic is the best on the market at the minute. I just wish that I could use the fingers individually but I’ve been told this will come in time.
Presumably you’re still an active individual, how robust is the prosthetic and are you afraid of damaging such an expensive piece of kit?
The prosthetic is very robust, I wear the arm most days and I’ve not had any problems with it at all. It such a solid piece of kit.
What was it like when you found that you really were able to operate the prosthetic with your mind?
The first time I could use the prosthetic with just thought was unbelievable and put a huge smile on my face. The teams at both Ottobock and Headley Court were great with everything and I was just overwhelmed with the finished product. I am very happy and honoured to have this prosthetic. It’s part of me now and it’s very useful.
How It Works
A surgical procedure (targeted muscle reinnervation) is used to redirect nerves that originally served the amputated limb to another (substitute) muscle group. (For Corporal Garthwaite, the muscles in the chest were perfectly placed for the job.) The nerves are reconnected, allowing the brain to send signals to the selected muscles to contract. Electrodes placed on the skin connected with a tiny computer translate them into specific movements.
TMR technology is much quicker than traditional myoelectric processes and allow users the ability to control more than one joint at a time and so open and close their hand, rotate their wrist and flex their elbow simultaneously.
