When asking 'how are prosthetic arms controlled?' there are two elements to look at. The first is the physical components that can be used to physically move or adjust a prosthesis per the wearer's wishes, so it carries out whatever action they want it to at any given time; for example, gripping an object or waving hello. The second element is how inputs or instructions can be sent to a prosthesis so that it can carry out these movements. The ExpHand team will look at both of these elements in today's blog, and we can tell you that given some fairly recent developments in technology it's quite an interesting ride, so let’s get started and answer today’s key question - ‘How are prosthetic arms controlled’?

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How are prosthetic arms controlled?
The components that can be used to have move / adjust a prosthesis

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The components and technology that can be used to physically move or adjust a prosthesis at the moment essentially boil down to two options. So, when we ask the question 'how are prosthetic arms controlled?' the answer in most cases is through the use of either cables, or motors.

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How are prosthetic arms controlled?
How inputs / instructions can be sent to a prosthesis

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With the body

The simplest way to control your prosthetic arm is by sending instructions with the body. For example, you could use a strap around your opposite shoulder to pull on one of the cables that controls your prosthetic wrist. This approach can work well if you have enough functional movement in that arm, but it may not be ideal if there's only limited ability or strength available in that limb.
There are more sophisticated options as well--for example, using a pressure pad on one's chest or stomach (or even directly on top of their skin) could allow them to send signals using muscle tissue that isn't even part of a limb.

 

With the mind

 

Myoelectric control
In myoelectric control, the prosthesis is controlled by the electrical signals sent from your muscles. These signals are detected by electrodes that are attached to the skin and then sent to a computer. The computer sends instructions to the prosthesis through a cable that runs down your back or through a wireless connection.
 

This type of control system is typically used for upper-limb prostheses that require more fine motor skills than other types of prosthetic arms (such as those used in industrial applications). It's also commonly used in sports because it allows users to move freely without having to think about controlling their limbs all the time--the user can focus on what they're doing instead of worrying about moving around their arm at all times!

 

Neuromusculoskeletal prostheses

Neuromusculoskeletal prostheses are simply the closest thing we have to fully bionic arms right now. They use the nerves and muscles to control a prosthetic limb using the same principles as myoelectrical control that we spoke about above. These prostheses are attached directly to the bone so there's no need for an external socket that fits over your stump, which may be more convenient for some, but it also means they're a more permanent solution and may not be a suitable option for children or young adults as these patients are still growing.

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Neuromusculoskeletal (NMS) systems require more surgery. This is because they are also attached directly to the wearer's muscles and nerves too, and use these connections to both receive instructions from the brain as to what to do or the movements to make, and relay information back to the brain. This is the crucial difference that elevates neuromusculoskeletal prosthetics further towards full-on bionics, since the ability for the brain to receive a signal from the prosthetic means that it is possible for the wearer to actually feel whatever their hand is touching. To find out more, why not check out this page from sciencedaily.com?

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How are prosthetic arms controlled?

In Conclusion

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These neuromusculoskeletal prosthetics are the current cutting edge of amputation, limb difference and prosthesis tech. As such they are likely to be pretty expensive and it's likely to be a while before we see them available on the NHS here in the UK (if ever). However, they do show what technology is currently capable of, and what might become 'the new normal' for how prosthetic arms are controlled in the future and the features wearers can expect.

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In the here and now however, once you've asked how are prosthetic arms controlled and you understand the options, the question then becomes about finding the right medical prosthetic and control method for the wearer. In most cases this is the one that quite simply lets the wearer get on with their everyday life - but whether that's myoelectric control, a set of input buttons or switches, or cable will be different for each person and their unique circumstances. If you're interested in learning more about how prosthetics work, life with a limb difference or the latest news and developments from within the limb different community we encourage you to head over to the ExpHand blog and check out more of our posts - such as these posts on inclusive children's toys and books, or this post full of advice for new parents of a limb different child.