Accessome
The war-focused civilizations of Antiquity evolved limb replacements due to the common impairment during battle. The earliest proof of prosthetics discovered to this day comes from a 3,000-year-old Egyptian mummy, found with a prosthetic toe made from wood and leather. A similar model from that time period, the “Cairo toe”, exhibits a more practical design. Around 300 BCE, the Romans developed the “Capua leg,” a prosthetic leg crafted from bronze, iron, and wood. The design provided support and mobility, but it couldn’t be acquired by the simple folk due to its value. Many prostheses of that time were intended for the use of nobles, and the materials used to make them were costly on their own.
During the Middle Ages, missing limb replacements became peg legs and hand hooks, still pricey to the average citizen. Small adjustments made by tradesmen, like the introduction of springs and gears, helped improve the flexibility of the design.
Ambroise Paré, a French surgeon and army barber, earned his title of Father of Modern Prosthetics after developing functional artificial limbs for all parts of the body. His designs mimicked the function of natural limbs, and his above-knee prosthesis is still used today.
Fast-forward to 1900, when prosthetic designs began to use more lightweight materials, like plastic.
Still, the general public was deprived of such innovations due to the high cost. One of the reasons artificial limbs have evolved in to the high-tech bionic tools we use today, and most probably why they began becoming more accessible in price and functions, is war. During the battles that took place around the globe in the 20th century, such as the First World War and the American Civil War, a lot of soldiers got their limbs torn or permanently damaged, and due to the high demand, military hospitals would fit disabled people with a prosthesis as part of their care. Soon, artificial limbs would become a marketable good, with factories opening and patents emerging. The opinion of the public also shifted in those times: prosthetics became an affair of the state, and proper care for those who had missing limbs was a necessity. Those thoughts enabled the revolution that allowed artificial limbs to become what they are today.
The Types of Prosthesis We Have Today
If in the 1900 the materials that were used in making limb replacements became more lightweight, in the past few decades we managed to find even better alternatives, such as aluminium, titanium and silicone, with plastic keeping its position. Prosthetist now come in different shapes and sizes, both literally and figuratively, this meaning that there are categories to choose from depending on the needs of the user and modern fitting techniques help design comfortable and practical artificial limbs.
There are 4 types of prosthesis depending on their localization: Transradial(replaces limbs below the elbow) Transhumeral(for above-the-elbow replacement) Transtibial and Transfemoral(below- and above-knee solutions).
When it comes to the porpoise of a prosthesis, the market offers a wide variety of choices for the amputee. Some artificial limbs might have a purely aesthetic role, while others could be capable of performing complicated tasks with human-like precision. There are 3 types of prosthesis categorized by their power origin: Body powered: This is where the body controls the prosthesis. For instance, a cable may move from one shoulder to the prosthetic hand, so the prosthesis activates as you move your shoulder.
Motor powered: These prosthetics have buttons to control movement. A prosthetic hand, for example, may have a specific button to articulate wrists and fingers for gripping objects.
Myoelectric Powered: This new technology allows for the powering of prosthetic limbs by electrical signals sent via electrodes placed on the skin.
Myoelectric Prosthetics: A New Chapter
In the early 1940's, Reinhold Reiter, a physicist working with the Bavarian Red Cross, developed the first model of what would become the myoelectric prosthesis. During the same times, but scattered across the globe, others attempted or proposed the same principals. The late Professor Norbert Weiner of Massachusetts Institute of Technology is reported to have suggested the concept around 1947. Battye, Nightingale, and Whillis at Guy's Hospital in London developed a myoelectric control system for a powered prosthesis in 1955 in what was for many years thought to be the first demonstration of this principle. Soviet scientists were apparently the first to use transistors in a myoelectricaly controlled prosthesis. A so-called Russian Hand was sold, although not too many, in Great Britain and Canada. The prosthesis was the first semi-practical myo-electrical limb to be used clinically.
What makes myoelectrical prosthetics far more accessible in model is their concept: they are literally powered by the brain. Sensors are placed on the surface of the skin above the residual muscles in the amputated limb. Those sensors detect electrical signals produced by muscle contraction, which are then amplified and processed to control the movements of the prosthetic limb. This cutting-age technology allows the user to control their prosthesis as they would control a natural limb, but, like biological membranes, motor skills require training. The effectiveness of a myoelectric prosthetic limb largely depends on the sophistication of its signal processing and control algorithms. These algorithms are designed to accurately interpret the myoelectric signals and generate appropriate movements.
Myoelectric prosthetics offer several advantages over traditional prosthetics: their enhanced functionality offers the amputee a higher level of dexterity, the realistic aspect of the artificial limb can boost the morale of the user and the customization of the device enables a higher grade of comfort.
This doesn’t mean, however, that myoelectric prosthetics are perfect. Ensuring consistent and reliable signal detection remains a challenge, due to the constant changes in the body and electrode placement. The powering component of the prosthesis can also pose a threat to the overall functionality of the device: the myoelectric limb works with the help of batteries, and frequent recharging might become a demand due to the constant energy drain. Another disadvantage that was as prevalent in the prosthesis of the past as it is in our days is the price. While it’s true that the cost of an artificial limb has become far cheaper, an average amputee still might not be able to afford some of the newest technologies. Luckly, researchers and scientists are working on improving the price without condemning the structural sound of the myoelectric device.
Touch: A Reignited Sense
A less discussed disadvantage amputees with transradial or transhumeral prosthesis have to face is the loss of an largely important sense: touch. Non-disabled people rarely realize how often they use feeling to identify the world around us. Grabbing an object without looking, releasing our grip from an item that can harm us, sensing the temperature of something, all of these actions are impossible for someone with an artificial limb. However, as technology evolves further and as scientist discover previously unthinkable solutions to our problems, feeling the world with a prosthetic has become possible. By planting brain-computer interfaces(BCI) in the areas of the brain responsible with moving and touch, not only can the person control their prosthesis with their mind, as seen with myoelectric technology, but they can also sense what their doing. Past tests proved to be less than satisfactory, the patients only experiencing faint signals proving that stimuli were active. Newer studies, tough, succeeded in mapping the brain areas and their corresponding triggers and adding feeling to movement and shapes. Researchers hope that, as electrode designs and surgical methods continue to improve, the coverage across the hand will become even finer, enabling more lifelike feedback. Although many challenges remain, these latest studies offer evidence that the path to restoring touch is becoming clearer. With each new set of findings, scientists come closer to a future in which a prosthetic body part is not just a functional tool, but a way to experience the world.
Conclusion
Artificial limbs have come very far from the purely aesthetic tools created in antiquity. Now, amputees can have the ability to control the movements of their prosthesis directly trough the brain, and soon to they will also be able to feel their actions. As technology continues to advance, we can only wait to discover what the future has in store for bionic devices.