Hand Prosthetics

Even 10,000 new upper extremity amputations are recorded every year. It constitutes a large number of people whose lives need some reorganization. Prosthetics comes with help to them, but surprisingly, only a half of the big group of the amputees decide to use prostheses.

Some of us may think that hand prostheses play only the aesthetic role. It is not true, a hand prosthesis can help an amputee regain his or her daily activity and complete many types of everyday tasks successfully. Thus, wearing a hand prosthesis is very important in the process of psychological recovery and return to the normal way of living, including work and recreation time. Since people differ from each other in their activities and needs, hand prostheses need to be personalized and treated individually.

As we have been observing recently, lower limbs prostheses has undergone a lot of technological development. When it comes to the upper limb prostheses, they are bringing more and more innovations and facilitation for the amputees as well. Developments in the area of prosthetics are going to go continuously further thanks to the constant advances in computer technology which works brilliantly in service of people in need.

The available types of hand prostheses

Cosmetic; Passive Functional

This type of a hand prosthesis constitutes a visual replacement of a hand. Although it is treated as a typical aesthetic type of a prosthetic device, it can provide help in some simple actions like carrying or balancing things. It is lightweight and undemanding in terms of the maintenance.

Recreational; Adaptive

As it has been already mentioned, individual patients may need extremely different prostheses, which depends on the type of their activities. Playing instruments, construction work or sports demand an individual approach in terms of the specific prostheses usage. The adaptive or recreational prostheses are the most suitable in such cases. They can be customized in such a way that in effect, the personalized prosthesis functions accordingly to the patient’s unique needs.

Conventional; Body Powered

Such a prosthesis works basing on a special harness system which is operated by the specific movement of a patient’s body. Its assets are: good durability, less weight than in the case of Myoelectric, and lower price. The maintenance does not require lots of effort, which is another good aspect of using this type of a hand prosthesis.

External Power; Myoelectric

Instead of basing on the harness system, this type of a prosthesis remains under control of an electric motor powered by batteries. A patient’s skin sends EMG signals which are collected by the sensors placed in the socket. Then, the signals are directed into a processor which manages the functioning of the motor. Unfortunately, the prosthesis is not easy in usage. So as to use it successfully, patients need a proper training.

Hybrid

This is a combination of the conventional and myoelectric types. The hybrid prosthesis provides a good solution for patients after the transhumeral (above the elbow) amputations. It can help regain the cooperation of the hand and elbow. The harness system and the externally powered motor work together to control the device which plays a role of the elbow joint.

Leg prosthetics

Probably most of us have heard about Oscar Pistorius – a man who had his two legs amputated below knees, but still able to run in Olympics. It was possible thanks to the aid of the right prostheses. Production of the artificial limbs has undergone a huge revolution. Nowadays, prosthetics are much more useful and helpful than they used to be in the beginning. They help people regain their previous life and activity, like in the case of two soldiers who after having lost their legs, received prosthetics and went back to the service. This situation constitutes a very optimistic example of how efficiently technology works and is constantly developing for people in need. Losing a limb is as traumatic and depressing as it used to be, yet it is no longer the end of someone’s normal life. Prostheses enable amputees to walk, jump and even run. Not to mention the fact that it helps from the psychological point of view.

There is a general division into BK (below the knee; transtibial) and AK (above the knee; transfemoral) prosthetics. However, there are also other possible disarticulations: of a hip, knee and ankle (with heel preserved).

Improvements of the Socket

Socket is a very important part of a prosthesis – it fixes the artificial limb to the remains of the natural one. It used to be made universal for everyone and then,since 1990s, thanks to Sabolich Prosthetics, it has been made for an individual. They developed the socket so that the weight could be distributed evenly across the existing limb. Their next improvements – bio elastic sockets or sense of feel technology- were aimed at making it possible to AK amputees to run and walk down the stairs. This has created the new necessity – surgeons must have started to carry out the amputation in such a way that it would prepare the limb for the prosthesis.

Microchips

“Intelligent prosthetics” entered the game at more or less the same time. The innovation provided by Chas. A. Blatchford & Sons, Ltd. used the microchips controlling prosthetic knees. This was the first step to make the prostheses’ movement more natural. Then, in 1998 the first usage of hydraulic and pneumatic control together with the microprocessor enabled to make walking adaptive to different speeds. These Adaptive Prostheses are quite expensive, though.

The C-leg

Not too much costly, adaptable type of a prosthesis. It imitates the movement of a natural knee, enables dynamic movement and calculates angles to adapt to the situation – all these thanks to the usage of a microprocessor and a lithium ion battery.

Flex – Foot

The type enabling patients to run and jump , the one used by Oscar Pistorius. It is made of carbon graphite blades. Their work resembles a spring – the blades bend and store the kinetic energy.

Future possibilities

Artificial limbs under control of a brain are not entirely a science – fiction creation now. There is a chance that it will be finally possible. Kevin Warwick proved that it is a matter of the future developments. He inserted electrodes into his median nerve which turned out to be successful in sensing the signals and make Warwick able to control a robotic arm. It copied his movement and gave a touch feedback through the implant.

No matter how much advanced the prosthetic technology is, it is going to go even further. There is some work to be done – achieving full mobility is finally proved to be possible.

3D printers helping the disabled?

The number of amputated limbs reaches as many as 15 million worldwide. It is a huge amount which, though, cannot picture how much of human emotional and physical pain is present in this situation. Losing a limb brings a drastic change of life, causing lots of stress and feeling of helplessness. Getting used to the situation is not the whole success. Yet another challenge is to find a solution which will regain the previous life activity as much as possible. Here prostheses come with help, but getting them (they are not cheap, unfortunately), learning to live with them and using them right become a difficult process with many obstacles to overcome. Luckily, there are more and more solutions which may help disabled people come back to normal life easier.

The lack of money no longer means an end of dreams about a prosthesis. The example of Selvan Mohan shows that crowdfunding may come with help also in such terrible life circumstances. He used YouCaring.com – a crowdfunding platform – to find help in funding his leg prosthesis.

What about people who cannot use such a platform? There are many people among inventors and businessmen who are willing to help those with problems in financing their prostheses or who cannot gather funds by the means of crowdfunding. With the use of 3D printers and some help from the outside you can achieve a simple prosthesis. We hear about such generosity from time to time in the news. It is a great hope for many people.

Yet another source of the precious hope is an organization – e-NABLE. Their work by gathering medicine and industry leaders and public policy to create an event which aims at not only educating professionals, but also at donating upper limb prostheses to children. A prosthetic hand created by their group of volunteers cost $50. All this thanks to 3D printed parts got together by the use of widely accessible screws and connectors. The organization has already helped many people in need of a hand prosthesis with the help of their global network of volunteers. Moreover, they aim at providing an open hand design files for printers.

As we can observe, innovative 3D printing has brought a new fertile and promising ground for prostheses industry. By making it much cheaper and more available for even the poorer group of people in need, it creates a great amount of hope for better life, even after so tragic event as is losing a limb. A leading trauma surgeon – Dr. Albert Chi admits that the $50-costing 3D hand appears to be of a great potential and is a chance for people who are in need of help, yet, paying from $30,000 to even $50,000 for a new limb is impossible for them.

For now, 3D prostheses production is still not sufficient and cannot solve the whole problem. However, observing the process of growing interest and a gradual improvement in the area, the appearance of new, cheaper and much easier available possibilities creates hope. This new “art” of making prostheses brings new opportunities and this is crucial. Let’s work on the better future.

Prostheses – artificial limbs


You may not even know that you have met a person with a prosthesis. The modern models are designed in such a way that they look very realistic, and they not only look good, they work like the real limbs. Thanks to the advance in technology, it has finally become possible to walk, run, swim or even climb with an artificial limb. Nowadays, the most innovative models give an arm/a hand prosthesis owner a power to control his or her fingers separately.

This invention has brought so much improvement to plenty of disabled people’s lives that it can surely be included in the group of the biggest inventions of all time. Prostheses help regain our priceless independence and feeling of normality.

Prosthesis – what is it?

In other words it is an artificial/prosthetic limb. Although our limbs are irreplaceable, prostheses are some kind of artificial replacements for them. Such a substitute is needed in many cases of either a lost limb – in many different circumstances – or an innate lack of a limb. A cosmesis is a type of prosthesis which plays an esthetic role only, usually it has no other functions. In the case of prostheses which are more functional than cosmeses, the artificial limbs consist of wires and metal rods and are supposed to be hidden by clothes.

What are the types of prostheses?

There are four main types:

  1. Below the knee – BK, transtibial – a prosthesis of a lower leg.
  2. Above the knee – AK, transfemoral – a replacement for an upper and lower leg with an
    artificial knee.
  3. Below the elbow – BE, transradial – a prosthesis of a forearm.
  4. Above the elbow – AE, transhumeral – a prosthesis of an upper and lower arm with an elbow.

How do the artificial limbs work?

A prosthesis is build of a few elements –the limb, the socket, the attachment mechanism and the control system.

The limb is usually made from carbon fiber (strong and light material) and covered with foam or plastic in the colour of body. The weight of a prosthesis plays a crucial role for a user. Actually, our natural limbs weight quite a lot and it would be too hard to move with the artificial ones in the same weight.

When it comes to the socket, it is a very important part deciding about the comfort of using the prosthesis and the effectiveness of its work. It is a connecting part for the artificial and the remaining natural part of a limb – residual limb. It must be made by a professional prosthetist, well fitted and then, adjusted regularly.

The appropriate attachment mechanism is necessary to support the connection between the prosthesis and the residual limb. It can be in a form of an elastic sleeve, a suction socket, straps or harness.

The control system is a substitute for the natural brain-muscles cooperation. In the simplest prostheses the role of muscles is played by a system of cables, the artificial legs usually use just the gravity to work. More sophisticated prostheses are controlled by electric mechanisms. For example, in myoelectric the complicated system of electrodes and electric motors help control the artificial limbs similarly to the natural ones.

The good cooperation between a patient and a prosthetist is fundamental to successful work of a prosthesis. And generally, the process of getting accustomed to the new part of your body must take some time and trouble, yet it is well worth the effort.