Prosthesis

In medicine, a prosthesis (pl.: prostheses) is an artificial device that replaces a missing body part. This can happen when someone loses a limb or other body part due to physical trauma, disease, or a condition they were born with, known as a congenital disorder. Prostheses help people get back everyday functions or simply look like they did before.

People who have had to have a body part removed are called amputees. Special doctors called physiatrists work with teams of experts to help these individuals recover. This team includes prosthetists who make the prostheses, nurses, physical therapists, and occupational therapists.

Creating a prosthesis can be done by hand or with the help of computers using something called computer-aided design (CAD). This software lets experts design and test their creations using special 2-D and 3-D graphics, making sure everything works just right before it is built.

Types

A prosthetic device is designed to replace a missing body part, helping with appearance and function. Choices depend on personal needs, budget, and access to care. Prostheses can be for the face, neck, torso, or limbs.

Limb prostheses replace arms or legs. Upper limb prostheses can be passive (for looks), body-powered (using muscles), or myoelectric (using batteries and sensors). Lower limb prostheses replace legs at different levels, with newer designs using advanced materials and technology to help users walk more easily. Prosthetists make and fit these devices, and physical therapists help people learn to use them.

History

Prosthetics have a long history, dating back to ancient times. The earliest evidence comes from around 3000 BCE in ancient Egypt and Iran, where people used simple artificial body parts. For example, the Egyptians made wooden toes, and people in Iran used eye prosthetics made from bitumen paste and covered in gold.

Over the centuries, many famous people used prosthetics. A Greek story tells of Hegesistratus, who replaced his lost foot with a wooden one. In ancient Rome, Marcus Sergius had an iron hand made so he could hold his shield in battle. During the Middle Ages, knights often used basic prosthetics to help them hold weapons or shields.

As time went on, prosthetics became more advanced. By the 1500s, people were using prosthetics made from iron, steel, copper, and wood. Important inventors like Ambroise Paré created new designs that helped amputees walk and perform daily tasks. In the 1900s, new technologies like microprocessor-controlled knees made walking with a prosthesis feel more natural.

Today, prosthetics continue to improve with lighter materials like carbon fiber and new technologies such as bionic limbs. These modern prosthetics can mimic natural movements and help users feel more confident and independent.

Patient procedure

A prosthesis is a functional replacement for a limb that is missing, either because it was lost due to injury or was not formed correctly from birth. Prosthetists are the specialists who design and manage these devices. They usually start by making a plaster cast of the patient's remaining limb, and then create a custom-made prosthetic using strong, lightweight materials like carbon fiber and titanium. Some advanced prostheses even have special electronics to help them stay stable and work better.

Current technology and manufacturing

Over the years, artificial limbs have improved with new materials like carbon fiber. These materials make limbs stronger and lighter, which helps people walk more easily. They also look more realistic, which is important for people who want to wear their artificial limbs in public.

Electronics now play a big role in artificial limbs. Myoelectric limbs use muscle movements to control the limb. Computers help design and make these limbs. Most modern limbs attach to the remaining part of the person's leg or arm using belts, cuffs, or suction. The limb fits into a socket, and often a soft liner is used to make it more comfortable.

Making a prosthetic socket starts with capturing the shape of the remaining limb. This can be done with a plaster cast or digital scanning. The socket is then made to fit this shape perfectly. The goal is to make the limb feel comfortable and stable.

Artificial limbs are made in several steps: measuring the limb, creating a model, fitting a liner, forming a thermoplastic sheet, making the socket, and assembling the limb. Some limbs are controlled by the person's body movements, while others use electronics.

For lower-body prosthetics, there are two main types: those for legs above the knee (trans-femoral) and those for legs below the knee (trans-tibial). The socket is very important because it connects the limb to the person’s body. The foot of the prosthetic helps the person walk smoothly, and the knee joint in above-knee prosthetics helps the person bend their leg naturally.

Some modern knee joints use microprocessors to help the limb move more like a natural knee. Myoelectric prostheses use muscle signals to control the limb. Robotic prostheses are being developed to help people control their limbs even better. These use sensors and computers to translate brain signals into movement.

Prosthetics are also being made from recycled materials, like plastic bottles, to help the environment.

Direct bone attachment and osseointegration

Main article: Osseointegration

Most prostheses are attached to the outside of the body, but this can be uncomfortable. Direct bone attachment is a way to connect an artificial limb more closely to the body. This method uses a special implant made of titanium that is placed into the bone where the limb is missing. Over time, the bone grows around the implant, creating a strong bond. After this, a small part called an abutment is added, allowing the artificial limb to be attached securely.

This method helps people have better control over their prosthetic and wear it for longer periods. However, it does have limits, such as avoiding high-impact activities like jogging, to protect the bone.

Cosmesis

Cosmetic prostheses help to cover injuries or make a missing limb look more natural. Today, we can create very lifelike artificial limbs using materials like silicone or PVC. These prosthetics can look just like real hands, with details such as freckles, veins, and even tattoos. Custom-made versions are very detailed but cost a lot of money, while standard versions come in different sizes but are usually not as realistic. There are also silicone covers that match a person's skin tone, though they may not include details like freckles. These cosmetic prostheses can be attached to the body in several ways, such as using adhesive, suction, or special stretchable material.

Cognition

Main article: Neuroprosthetics

Neurocognitive prostheses are devices that could help the brain with thinking processes like focusing, remembering, and using language. These are not yet available, but scientists are working on them to help people who have conditions such as stroke, traumatic brain injury, cerebral palsy, autism, and Alzheimer's disease. Some tools, like reminder devices, already help people remember important tasks, and other small devices guide people through daily activities.

Prosthetic enhancement

Further information: Powered exoskeleton § Research

Beyond everyday artificial limbs, special devices help amputees or those born without certain body parts to take part in sports and fun activities.

In science fiction and real science, people think about using super-advanced artificial parts to replace healthy ones and do even better things. Famous thinkers and scientists talk about whether this is right or good. For example, in 2002, a scientist named Kevin Warwick had a tiny device put into his body so a robot could move just like his real arm.

Some companies make very smart artificial arms that work with the brain, like the “Luke arm.” Testing started in 2008, and it was approved for use in 2014. Scientists keep finding new ways to make artificial parts fit better and feel more natural.

Design considerations

When creating a transtibial prosthesis, several important factors must be considered to ensure it works well for the user. Key elements include how well it fits, how it stores and returns energy for movement, how it absorbs impacts, and how it stays stable on different surfaces. Other important aspects are how easy it is to use, its appearance, cost, and availability in different sizes.

Designing prosthetics should involve people with disabilities in the process. True "design for disabilities" means working together with individuals who have the relevant disabilities, ensuring that the designs truly meet their needs and experiences. This approach helps create better, more effective prosthetics that support users in their daily lives.

Cost and source freedom

In many countries, the cost of a prosthetic limb can vary greatly. In the United States, a typical prosthetic limb can cost between $15,000 and $90,000. With insurance, patients usually pay a portion of this cost, depending on their plan. In places like the United Kingdom, Europe, Australia, and New Zealand, state funding or insurance often covers the full cost.

There are also lower-cost options available. For example, some organizations create basic prosthetic devices for developing countries. With advances in technology like 3D printing, it is now possible to make affordable prosthetics. One notable example is the "Hero Arm" developed by Open Bionics, which uses 3D printing to create personalized prosthetic hands at a lower cost. These innovations aim to make prosthetic limbs more accessible to everyone.

Main article: 3D Printed Prosthesis

See also: 3D printing, Open-source hardware, Modular design, Thingiverse, and Open Bionics

Low-cost prosthetics for children

See also: open-source hardware and 3D printing

Many children lose a limb due to disease, injury, or conditions they are born with. In some places, getting a prosthetic limb can be expensive, so special low-cost solutions have been created to help these children. These solutions use simple, locally available materials and can be very helpful.

Some examples of low-cost prosthetic devices include a hand-held pole with a leather support, limbs made from bamboo, PVC, or plaster, an adjustable limb made from a bicycle seat post, the Sathi Limb from India made with thermoplastic parts, and Monolimbs which are strong but need careful fitting. These options help children move and play more comfortably.

Cultural and social theory perspectives

Some thinkers have explored what it means for people to use artificial body parts. They wonder if prostheses fix something missing or if they help us do new and interesting things. These ideas connect to how we understand our bodies and the world around us.

Prostheses can affect how people feel about themselves and how others see them. For someone who has lost a limb, using a prosthesis can help them feel more confident and less different. However, the experience of losing a limb can be very hard emotionally, causing feelings of sadness, anxiety, and sometimes anger. These emotions can be especially strong right after the loss or injury.

There are also ethical questions about how prostheses are developed and tested. Some concerns include how animals are used in research, whether patients fully understand what they are agreeing to when testing new devices, and whether people have realistic expectations about how well a prosthesis will work.

Finally, there are debates within the prosthetic community about whether to use a prosthesis at all. Some people feel that they can manage well without one, while others find them helpful. Not every person who has lost a limb chooses to wear a prosthesis, and that choice is respected.

Notable users of prosthetic devices

Some well-known people have used prosthetic devices. Henry William Paget, 1st Marquess of Anglesey lost his leg at the Battle of Waterloo and used a prosthesis afterward. Marie Moentmann, a child who survived an industrial accident, also used a prosthetic device. Terry Fox was a Canadian athlete and humanitarian who became famous for his cancer research activism. Oscar Pistorius, a South African sprinter, used prosthetics to run professionally. Harold Russell, a veteran of World War II, won an Academy Award for his acting and was known for using a prosthetic arm.

Mythological

In ancient stories, heroes sometimes lost body parts in battles but were given special replacements. For example, Nuada, a mythical king, lost his arm in battle and was given a silver arm to take its place. Visphala, mentioned in the Rigveda, lost a leg in battle and was given a leg made of iron.