Life & Limb: The Evolution of Prosthetics

“We have always held to the hope, the belief, the conviction that there is a better life, a better world, beyond the horizon.”

These were the hopeful words of Franklin D. Roosevelt, a man born on the tail end of the industrial revolution, where we as a species first grasped the true, constructive, and destructive powers, we wielded over our world. He had lived to see the Empire State Building rise into the sky, and died shortly before the atomic bomb did the same.

Over a century later, accelerated advances in science and technology have stripped almost every hobble from our collective vision, opening our potential to realms that men in Roosevelt’s lifetime would have dismissed as fantasy. But, while the digital age has ushered in a new era of convenience and connectivity, this innovative decade also produced an explosion of advances in an area a paralyzed Roosevelt would have held dear — making the shortcomings of our frail human bodies whole again.

From outfitting sprinters like Oscar “Blade Runner” Pistorius from South Africa, a double leg amputee competing in 2012 Summer Olympic Games, to giving wounded war veterans the chance to continue their mission, modern prosthetics are changing lives for the better. Learn more about this amazing technology, starting with its history below.

A Bit of History

A Toe in the Water: The first known prosthesis, dubbed “The Cairo Toe”, is over 3000 years old and was meticulously designed to mirror the real thing.

Centuries ago, amputation was the default treatment for any serious wound to a limb. In the age before antiseptics, this scorched-earth policy was the medical world’s only defense against the slow creep of infection. While it certainly lowered death counts, options for living a “normal” life after such a procedure didn’t really exist. Prosthetics (Greek for “attachment”), were incredibly rare and mainly cosmetic — but a few functional varieties did exist. The mechanics of these first attempts at retrofitting the human body were rudimentary and awkward for the user, but given the times, impressive in their ingenuity.

The first known prosthesis was discovered in Cairo, Egypt and dates all the way to as early as 950 B.C. There, a mummified woman of noble birth estimated to be in her 50s was found with a prosthetic big toe constructed of wood and leather that even featured a carved toenail — a nod to replicating the original as much as possible.

Breakthroughs in the field made in the 16th & 18th centuries would influence the field of prosthetics for generations.

During the Middle Ages, when battle involved swords and crushing weapons, the loss of a limb was not uncommon, spawning a new era in prosthetic design. These devices were often constructed of iron and began featuring functional elements, such as providing a place to hold a shield during combat. Talk about commitment. During the same period, the use of wooden or “peg” legs and hooked metal hands by seafaring men began to appear, as these materials were readily available on ships. But such occurrences were still rare, largely due to the absence of sterile conditions, medically capable personnel (the ship’s grungy cook might’ve been the resident surgeon) and the ability to mitigate the excruciating pain — since biting a stick and a taking a swig of whisky was likely only sufficient for the toughest of men.

The real question the world should be asking isn’t “will prosthetic science match what evolution spent 200,000 years perfecting”, but rather, “when will it surpass it?”

In the 16th century, Ambroise Paré — the official surgeon for French royalty who specialized in battlefield medicine — invented prosthetic legs with special attachment equipment and locking knees, hinged prosthetic hands and ocular prostheses made out of precious metals. In the late 17th century, a Dutch surgeon, Pieter Verduyn, took another step forward, creating a prosthesis for the lower leg that incorporated unique hinges for articulation and movement, as well as a leather cuff that provided an improved method of attachment to the leg. These pioneering innovations by both men would influence prosthesis development for generations.

William Selvo’s prosthetic arm patent in 1857 pioneered the use of body powered actuation.

The main damper to progress during the next two centuries was pain management, which complicated physicians’ abilities to properly prepare amputees’ limbs for prosthetic attachment. In the 1840s, with the advent of gaseous anesthesia and improved sterilization, surgery time was lengthened, allowing doctors the opportunity to perform amputation with greater precision. As a result, the use of prosthetics began to rise, and the patient success rate increased rapidly. In 1857, William Selvo patented a prosthetic arm which made use of muscular motion from the opposite, functional arm to activate the prosthesis: essentially, body powered actuation. A system of straps and cords enabled the user to actuate the prosthetic fingers, albeit awkwardly, making them open and close.

Harold Russell, a double hand amputee, won the Oscar for Best Supporting Actor in the 1945, helping to bring the need for better prosthetic design into the public eye.
Nearly a century later, a mass influx of injured World War II veterans soon made the need for prosthetic advancement a mainstream issue. The struggle to adjust to life back home, exacerbated by the debilitating and wrongfully shameful loss of a limb was well captured in the 1945 movie, The Best Years of Our Lives, where real-life WWII veteran Harold Russell, a double hand amputee, won the Oscar for Best Supporting Actor. His portrayal was no doubt a reflection of his own struggles after losing both his hands in military training accident. That same year, The National Academy of Sciences was formed by the Federal Government and created the Artificial Limb Program in 1945. This program targeted the need for advances in prosthetics due to the sheer volume of soldiers that required focused care in the area of artificial limb development.

The Basics

Take Note:

Key Prosthesis Components:

1. Socket: The portion of the prosthesis that attaches to the residual limb, it’s essentially a housing that partially shrouds the point of amputation. It is vital that the socket fits the residual limb as well as possible because transfer of impact or force (especially in the case of a prosthetic leg) can make movement difficult or irritating to the interfacing skin. A soft, shock absorbing layer at the top of the socket is often used in order to mitigate these issues.

2. Pylon: This is the core of the prosthesis, providing support and strength to the artificial member. Typically, the pylon has been constructed of metal for strength and longevity in the modern era. Today’s most advanced prostheses have now replaced heavier metals with lighter materials such as carbon fiber. The pylon is also usually coated by a softer, foam-like material that’s intended to match the color of the natural skin so as to conceal the prosthesis in day-to-day usage.

3. Suspension: This part is essentially the method by which the prosthesis at the socket point attaches to the residual limb, utilizing harnesses, straps or sleeves. Often a suction method is used and the airtight seal keeps the prosthesis in place.

Though advances in materials and designs have significantly enhanced the dexterity and versatility of today’s prostheses, their essential components of have remained virtually the same.

That said, they are by no means produced in a cookie-cutter fashion. Instead, each must be customized to the user and is based on a variety of factors including the type of amputation, the remaining muscular and skeletal structure and body size. Advances in measuring and creating digitized renderings of patients have drastically improved the prosthesis customization process, but no artificial limb is perfect right out of the box.

Typically, the socket is adjusted or modified within the first several weeks of the amputation due to residual limb size changes and a reduction in swelling or muscle atrophy at the wound site. Physical therapy is also a key aspect of prosthetics use, since the way the body accommodates the artificial limb, as well as the psychological adjustment, is often the biggest hurdle for patients.

Prosthetics Today

After a grenade took his hand, Medal of Honor Winner Leroy Petry opted to have some of his existing forearm removed as well, since his own ability to turn his wrist would not be as good as a prosthesis. He is still serving his country today.

Current technology has transcended the purely mechanical nature of prostheses and elevated it to the biomechanical. Electronic sensors built into advanced prosthetics now enable a level of dexterity and functionality never before imagined. It’s not only changed the way wounded military personnel adjust to life back home, but also sometimes enables them to serve our country again, even after suffering a traumatic loss.

In the case of Sergeant 1st Class Leroy Petry, recipient of the Congressional Medal of Honor, a biomechanical hand allowed him to rejoin the Army Rangers. Sensors in the prosthetic forearm and hand pick up electro-muscular signals which would normally cue his own hand to move, giving him an intermediate level of dexterity that mimics basic hand movements.

Companies such as Adidas and Nike are also developing their own prosthetic technology for high performance athletes. Adidas is in the process of creating their Symbiosis prosthetic line, utilizing electromagnets and high-grade materials such as carbon fiber, sorbothane and aluminum — shaped more like a human limb than other prostheses currently on the market. The electromagnets send wireless signals to the base of the lower leg section to move the prosthetic in a more natural fashion.

Nike’s Sole prosthetic shoe was built in collaboration with prosthetics manufacturer Ossur and triathlete Sarah Reinertsen

Nike, in conjunction with prosthetics designer and manufacturer Ossur, has created The Sole, a prosthetic shoe built in collaboration with triathlete Sarah Reinertsen. The Sole utilizes a high-tech material called Aeroply, which enables the “foot” to more effectively interface with Ossur’s carbon fiber blade prosthetic leg, providing a host of benefits including better stability, a more natural running stride, improved energy return and impact recovery.

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South Africa’s Olympian Oscar Pistorious serves as an inspiration to the abled and disabled alike, posting sprint times most could never reach, even with years of training.

These cutting-edge advances in the field of athletics have recently thrust prosthetics back into the public consciousness and raised a new issue — one pioneers like Selvo and Paré would never have imagined centuries ago. Specifically, have improvements in design now made artificial limbs better than their natural counterparts?

This was the question asked about Oscar Pistorious, who was denied qualification in the 2008 games based on the decision that his prostheses gave him an artificial advantage over other “natural” athletes. Pistorious is not the fastest man in the world, but his times in various sprinting events certainly reflect a peak level of performance, unobtainable by most on the planet. He has run the 100m in 10.91 seconds, the 200m in 21.58 seconds and the 400m in 45.07 seconds, setting disabled sports records in the first two events in the process. These times compare to world records of 9.58 and 19.19 seconds, for the 100 and 200m sprints set by Usain bolt, and a 400m time of 43.18 seconds set by Michael Johnson. While these differences aren’t insubstantial in a sport where milliseconds amount to minutes, they certainly imply that the notion of a “physical disability” from the loss of a limb and all of the stigma that comes with it, may be woefully outdated.

If this history provides any insight into the future, it’s that the inspiration provided by incredible individuals like Oscar Pistorious will one day lose its novelty as continued progress in prosthetic design will not only allow the disabled to fully recover from their injuries, but to excel as well. The real question the world should be asking isn’t “will prosthetic science match what evolution spent 200,000 years perfecting?”, but rather, “when will it surpass it?”

Ben Bowers also contributed to this post

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