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stemandleafdiagram · 19 days ago

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Prostheses

(stemandleafdiagram long-form post!)

~2300 words

Recently, my friends and I have been having vigorous debates with everyone we talk to about whether they would rather lose an arm or a leg. We are all lucky enough for this to be a hypothetical, and as the debate went on we decided that prosthetics would be available for whichever limb we chose to lose. This made me realise that I did not know much about artificial limbs and how far they have developed at all, as in my head it was just a blur of vague science-y magic, so I started doing a bit of reading!

First off, a prothesis or prosthetic implant is an artificial device that replaces a missing body part. They are either created by hand or with a CAD. There is a wide range of prostheses types nowadays, but the story of the development of the first artificial limbs starts in Ancient Egypt, with two artificial toes dating to before 600BC. The first one, known as the ��Greville Chester toe”, was made out of cartonnage, and is about 2600-3400 years old! Cartonnage is a type of papier-mâché with glue, linen, and plaster. Different cultures have different ideas about what makes a person “whole”, so it can be uncertain as to whether these early prosthetics were for appearances or for functionality. As it does not bend, however, historians reckon that the Greville Chester toe was probably cosmetic. The second toe, the “Cairo toe”, was the more advanced of the two. Likely to be a practical cosmetic due to its flexibility, this toe was refitted for the wearer multiple times.

(Credit: Dr Jacky Finch, BBC)

Toes were not the only early prosthetics! Another early prosthetic was the “Capua Leg” from Italy, dating back to 300BC. It was made for a Roman nobleman, and was made out of bronze and hollowed-out wood. The leg was held up with leather straps. Sadly, it was destroyed in WW2 but there is a replica of it at the Science Museum in London. Another famous prosthetic was Götz von Berlichingen’s iron hand. He was a German mercenary who lost his right arm in battle, and had two mechanical iron hands made. The second one in the image below allowed him to hold objects.

Early artificial limbs were made out of heavy materials, such as wood and metal. They remained rather basic during the Middle Ages, and people who could afford them could have basic hand hooks or peg leg equipped. Knights were often fitted with simple prosthetics that allowed them to hold up a shield or grasp a sword to let them continue a career in fighting, and prosthetics were crafted by tradesmen.

In the 1400s to 1700s, prostheses from countries such as France and Switzerland started to incorporate mobility using hinges, cables, gears, cranks, and springs, allowing hands to have articulated fingers and limbs to rotate or bend.

The development of artificial limbs really got rolling after the American Civil War in 1860. The huge number of casualties caused the demand for artificial limbs to quadruple, and many veterans started designing their own prosthetics. For example, James Hanger was one of the many soldiers that lost a leg in the fighting, and found it understandably difficult both physically and mentally to resume daily life with a peg leg. As an engineering student, he designed a limb that was able to bend at the knee and the ankle and patented it. It is called the “Hanger Limb”:

It was also the first leg to use rubber in the ankle and cushioning in the heel to make wearing it less painful.

Moving along, the development of artificial limbs was again accelerated by war. A couple years before World War 1, in 1912, David W. Dorrance patented the split-hook design for upper limb prostheses.

This invention allowed users to continue their labouring jobs as they could now grip and manipulate objects. Additionally, during the war, mass-production of prostheses started to happen for the enormous number of casualties. Towards the end of the war, people started to experiment with materials other than just wood, with metal being used in particular. Using metal instead of wood would mean that repairs (extremely time consuming) were needed less often. The production of limbs was also standardised, meaning that less time was needed to make and repair them, but fitting processes were still done so that each war veteran still got a personalised limb.

In World War 2 there was about half as many amputees from the war. This was due to advances in surgical techniques, improvement in treating infections, and increased availability of blood transfusions after WW1 reduced the need for amputation. However, this doesn’t mean that there wasn’t still a huge demand for artificial limbs. In the UK, Queen Mary’s Hospital in Roehampton became the centre for manufacturing, where tens of thousands of war pensioners were able to get their own prosthesis.

On the topic of prosthetics made for special activities I have to give a special mention to this prosthetic:

(Credit: Wellcome Images CC BY 2.0/Wikimedia)

This arm prosthetic limb has widespread fingers, a padded thumb and little finger, and the middle 3 fingers are smaller than normal. If you haven’t guessed, this hand was used for playing piano! The special modifications allowed the user to span 1 octave. The idea of specialised artificial limbs gained traction around 1900, leading to prosthetics like these. Unfortunately, the owner of this hand is unknown, but as a piano player I think this hand is absolutely fantastic!

In the 1970s-1990s, lighter, more durable, and more flexible materials began to be introduced to replace wood and leather in limbs, such as plastics, resins, and carbon fiber. These materials are also able to make the limb mimic the look and feel of natural skin better as well as being light and easy to clean.

As you can imagine, the actual manufacturing of an artificial limb is rather extensive. This is done by a prosthetist, who is responsible for the prescription, design, and management of a prosthetic. Firstly, the residual limb is measured, and so is the user’s body to determine what size limb is needed. Most modern artificial limbs are attached with a belt, cuff, or suction, so a silicone liner is fitted. Next, the socket and plastic parts of the limb are formed, followed by the metal parts.

Although prosthetic limbs can be extremely useful in allowing a person to navigate daily life with much more ease after an amputation, not everyone will benefit from one. For example, whether a prosthetic leg would be beneficial can depend on the person’s health and condition. There needs to be enough soft tissue to cushion the remaining bone, the skin on the residual limb needs to be healthy, and if the amputation was done below the knee it can make the prosthetic easier to use as the knee joint is still intact, require less effort to move. Having a prosthetic leg isn’t easy either. Users may suffer from excessive sweating, or hyperhidrosis, which can lead to skin issues and affect the fit of the prosthesis. The fit of the socket can be affected if the residual limb changes shape after amputation, and weakness in the limb can mean it’s difficult to use the prosthetic for long periods of time.

New technology is constantly improving and developing, and as time goes on prostheses will become much more advanced, allowing users to use their prosthetics with more ease and comfort. Nowadays, prosthetics are advanced, increasingly specialised, and are becoming easier and intuitive to use. We have come a long way!

In particular, bionic and myoelectric limbs are gaining traction. First developed in the USSR in 1958, a myoelectric limb is controlled by contractions of the actual muscle. This is done using electrodes that sit on the skin inside the limb socket that detect electrical signals given off when muscles are contracted. These signals are sent to a controller to be converted into motions. This allows the user to control the limb with their own muscle contractions! They are powered by motors and batteries. These prosthetics have many advantages - they could look more natural, and could be better for people experiencing phantom limb pain (when you feel pain in a limb that has been amputated), and mean that users don’t need to use their other limb to complete tasks, but they may not be as durable. As well as that, myoelectric limbs cannot get wet, which can be a pain, so advancements have been recently made to integrate waterproof materials into the devices.

(Credit: Open Bionics)

This is the Hero Arm, an example of a myoelectric prosthetic made by Open Bionics. As evident, these new limbs can be designed to look really cool and robotic! If someone had an amputation above their elbow or at shoulder level, they can undergo targeted muscle reinnervation surgery (TMR) which can reroute the nerves that controlled the arm or hand muscles so that they can still control the myoelectric.

Of course, artificial limbs are not the only prostheses available. Craniofacial protheses are ones for the ears, nose, eyes, teeth or neck, for example. Passive devices can be made for upper limbs, which are mainly for cosmetic purposes or specific activities. Myoelectric technology is also available for prosthetic fingers, hands, and elbows.

The advancement in 3D printing also mean plenty of good things for artificial limbs, as it allows the rapid production of customised prosthetics so that each one is tailored to the user and their needs. The parts that are 3D printed can be more lightweight as well. The manufacturing process is sped up and costs are reduced, letting a wider range of people have access to more advanced prosthetics. 3D scanners let prosthetists create digital models of amputees’ residual limb to make it easier and quicker to create their prosthesis.

Microprocessors that adjust the limb’s response based on terrain and activity can also be used. These are used in particular in knee joints, allowing the prosthesis to fit into the wearer’s natural gait, walk down stairs in an easier way, and even letting them run in some cases.

Although the development of these are still in early stages, the use of neural interfaces and AI could improve prostheses greatly. Neural interfaces can establish a connection between the nervous system and the prosthetic, which could mean that wearers will be able to feel sensations through their prosthetics using their own nervous systems! On the other hand, AI and machine learning can adapt to the user’s habits and preferences over time, such as their gait, grip, and other movements in order to improve the limb’s behaviour. One such example of this is Atom Limbs’ prosthetic arm, which is still in development, but allows the user to control it completely with just their muscle contractions.

The major issue with these modern prosthetic limbs is that they are extremely expensive. Atom Limbs estimated that their product would be priced at around £15,000, which is still considered fairly cheap compared to other bionic arms. The average person would not be able to afford one easily despite how innovative these new designs are.

Finally, what about artificial tissue and organ prostheses - how far are we with those? Well, artificial organs are bioengineered devices or tissues that are added into the human body to replace or augment existing organs, and there have been advancements in the development of many different organs. To help with sight, retinal prostheses can used - tiny microchip devices that allow information to still be obtained even if the original retinal cones and rods have been lost. They are now approved for use, but can only restore a limited amount of eyesight. For those who struggle with hearing, cochlear implants such as bone-anchored hearing aids (BAHA) can be implanted. They are able to carry the sound through the middle ear by sending the vibrations from the skull straight into the cochlea.

Continuing on, work has also been done for artificial nerves. As you may know, nerve cells in the central nervous system usually don’t regenerate, but nerves in the peripheral nervous system do, albeit slowly. One treatment for injured/lost peripheral nerves uses a nerve connection tube which connects two severed nerves and guides regeneration of the nerve. The development of artificial nerves is very promising for treating diseases such as Alzheimer’s. Next, to treat kidney disease, many people use external filtration systems such as dialysis, which are expensive and inconvenient. Research is being done into bioartificial kidneys instead. This is a device with two components: the haemofilter, which processes incoming blood to create ultrafiltrate, and the bioreactor, which uses kidney cells to process the ultrafiltrate. It can be implanted into the body and is about the size of a coffee cup.

The last artificial organ I wanted to take a look at was the heart. Currently, artificial hearts fall under two main types: the mechanical heart and the heart-lung machine. The mechanical heart is a device that acts as a pump for your blood and replaces the ventricles in your heart. Unfortunately, these are not permanent solutions, and are usually used temporarily by people with severe heart failure or during the wait for a heart transplant. On the other hand, the heart-lung machine (or the cardiopulmonary bypass) is used during open heart surgeries to remove blood from a person’s body, oxygenate it, then pump it back round the body.

A mechanical heart! (Credit: Abiomed)

In conclusion I think it is astounding how cool science and technology is! I love how humanity is able to use so many innovative ideas to help people throughout history and I really hope that this sentiment continues, as although our societies aren’t always made with disabled people in mind, everyone has the right to live in one equally.

#sciblr #science #medicine #artificial limbs #prosthetics #technology

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pointernationalinc · 2 years ago

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Artificial or Silicone Fingers, Nose, Feet, and Gloves Prosthesis: A Revolution in Restoring Function and Aesthetics

Prosthetic technology has come a long way, enabling individuals with limb loss and facial deformities to regain both function and aesthetics. While prosthetic limbs for arms and legs have been widely accepted and improved over the years, the development of artificial fingers, noses, feet, and gloves made from silicone materials represents a significant leap forward in the field of prosthetics. In this article, we will explore the advancements in these specific prosthetic devices and how they are changing lives for the better.

Artificial Fingers:

The loss of one or more fingers can be a life-altering event, affecting a person's ability to perform everyday tasks with dexterity and precision. Artificial fingers have made great strides in improving the lives of those with partial or complete finger amputations. These prosthetic fingers are typically made from silicone, a material known for its durability, flexibility, and lifelike appearance.

Silicone fingers are custom-made to fit the individual's residual hand, ensuring a snug and comfortable fit. They can be incredibly versatile, with articulating joints and realistic texture, allowing users to grip objects, type on a keyboard, and perform other fine motor tasks with remarkable accuracy. The aesthetics of these artificial fingers are also impressive, as they are meticulously designed to blend seamlessly with the natural hand.

Silicone Noses:

Facial deformities resulting from congenital conditions, accidents, or medical procedures can have a profound impact on an individual's self-esteem and social interactions. Silicone noses have emerged as a revolutionary solution for those in need of facial reconstruction. These prosthetic noses are custom-made to match the patient's facial features, ensuring a natural appearance.

Silicone is an ideal material for facial prosthetics due to its skin-like texture and coloration. It adheres securely to the skin, providing a stable and long-lasting solution. Patients who receive silicone noses often report a significant boost in self-confidence and improved psychological well-being. The aesthetic benefits of these prosthetics are evident, making them an essential part of modern facial reconstructive surgery.

Artificial Feet:

Losing a foot, whether due to injury, disease, or congenital conditions, can severely affect an individual's mobility and quality of life. Prosthetic feet have evolved to be more than just functional replacements; they are now designed to replicate the natural foot's biomechanics and aesthetics. Silicone plays a crucial role in achieving this.

Modern artificial feet incorporate silicone-based components to mimic the flexibility and shock-absorbing properties of a real foot. These prosthetics are designed to provide a more natural gait and enhanced comfort. The cosmetic aspect is equally important, as prosthetic feet are often equipped with lifelike skin covers to match the wearer's skin tone, allowing individuals to wear various types of shoes without drawing attention to their prosthesis.

Silicone Gloves:

For individuals with partial hand amputations or those who have lost their fingers, silicone gloves are a groundbreaking development. These gloves are designed to restore hand function and aesthetics simultaneously. They are custom-fitted and can be made to match the color and texture of the natural hand.

Silicone gloves often feature individual finger molds with articulating joints, enabling users to perform a wide range of activities. The material's pliability and texture make it easy to grasp objects, type, and engage in other fine motor tasks. Beyond their functional benefits, silicone gloves offer a seamless appearance, allowing wearers to regain a sense of normalcy and confidence in social and professional settings.

In conclusion, the advancements in artificial or silicone fingers, noses, feet, and gloves prostheses are changing the lives of individuals who have experienced limb loss or facial deformities. These prosthetic devices, made from silicone, offer a unique combination of functionality and aesthetics. They empower users to regain their independence, confidence, and overall quality of life. As prosthetic technology continues to evolve, the future holds even more promise for enhancing the lives of those in need of these remarkable solutions. The ongoing research and development in this field will likely lead to further improvements in comfort, functionality, and aesthetics, ultimately transforming the way we perceive and support individuals with limb loss or facial deformities.

#artificial limbs

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