Saturday, December 14, 2013

From Peg Legs to Exoskeletons: Prosthetic Ingenuity


Amputation to Ambulation: Walking Like an Egyptian

It’s hard to imagine the fake limb pictured above, extending forward to shake your hand. Its cold metal fingers clenching tightly around your warm, skin-protected hand. The unsettling feeling that washes over you as the prosthetic steel unguiculate tendrils dig in and squeak. However, just a few hundred years ago that wouldn’t have been so strange. The prosthetic industry was witnessing a boom, and a new science was on its way to making life livable for those who at one time, their situation would have otherwise been a death sentence.
Some of the first prosthetics that have been unearthed date all the way back to ancient Egypt. In 2000 archaeologist’s found a prosthetic big toe made of leather and wood buried just outside the ancient city of Thebes. This particular type of prosthesis is dated from 1069 to 664 B.C.  This beat out the previous record held by a bronze and copper leg found in Rome dating back to 300 B.C. The other advantage the toe has? It wasn’t destroyed by World War II bombing like the Capua leg was.


Yep…that’s one mummified wooden toe alright. It was found attached to a mummy that was later identified as Tabaketenmut who lived some time during the period from 950-710 B.C. After recruiting some volunteers and making a replica of the toe, researchers discovered that this toe was a functional prosthetic. Therefore the torch was passed from Rome to Egypt for the birth of prosthetics.
The Egyptians were also known to put non-functioning prosthetics on their corpses before burial. In the eyes of their God Osiris, a person was useless in the afterlife if they were not whole. Fake arms, legs, eyes, noses, ears, even genitalia have been fastened on the dead before being entombed. These devices, while they are prosthetics, weren’t functioning medical devices until the discovery of the above Cairo Toe.
While this prosthesis was pretty incredible, it was nothing compared to what would come. Today, we’re going to explore the birth of prosthetics all the way to what they are today. (Trust me, we’ve come a looooooooong way.)
Next, let’s go get a haircut real quick.

Just A Little Off The Top…


In medieval times surgery wasn’t considered a medical practice. In fact, it was considered to be more akin to the profession of a barber than that of an apothecary or an herbalist. (Truth be told, witchcraft was considered to have more medical value than surgery back then if that tells you anything…) In response to the shift in medicine after the sweep of plagues through Europe, the barbers and surgeons were merged.
See, physicians went through academic procedure in order to practice medicine back then and surgeons underwent apprenticeship instead. Therefore they were not recognized as a branch of doctors. Merging with the barbers just made sense. They both used sharp pointy tools right? (Perhaps Sweeney Todd was a medical professional.)
One barber-surgeon of note was Ambroise Paré. He is considered one of the founding fathers of modern surgery and pathology. He was a notable anatomist and his battlefield medicine practices are still taught today. (Not to mention he didn’t conform to the norm and pioneered antiseptics in wound treatment instead of cauterization and eventual death by shock).
In 1529, when Ambroise was only 19 years old, he introduced the practice of lifesaving amputation, and the development of prosthesis took off from there. He developed upper and lower extremity devices. His leg device was revolutionary; it featured an above-knee device that was a kneeling peg leg and foot prosthesis that had a fixed position, adjustable harness, knee lock control and other engineering features that are used in today's devices!
That’s pretty incredible for being almost 500 years ago. There were prosthetics before it but mostly used for cosmetic purposes. Hook hands and peg legs were common but this featured moving parts that mimicked human joints. (Albeit it wasn’t perfect) Paré also developed prosthetic eyes made of glass, jewels, and other materials, (once again, cosmetic only).
While there were many extremely notable advances from that point on in the field of functional prosthetics and amputation for the purposes of article length we can’t hope to cover them all. You can view a brief history of prostheses here. Now, let’s head to the Civil War.

Dr. Frankenstein’s Wars

It’s easy to see why the civil war saw so many amputations and prosthetics. Cleanliness wasn’t well understood and infections often led to amputations. By this point technology had advanced to a point where it was easier to simulate the ambulatory functions of limbs however by mimicking joints. By 1863, the midpoint of the war between the North and South a breakthrough was made.


Dubois Parmelee’s prosthesis was like none had seen. It featured a more comfortable suction cup for the knee and a polycentric joint allowing for full range of motion. The other interesting addition was the functional articulating foot. We commonly forget how important our toes and the bend of our ankles are to our balance. This prosthetic allowed for a less awkward movement. He also employed this method for upper extremities.
The original design called for it to be made of steel. As we all know, steel is heavy and bulky. Five years later a man named Gustav Hermann would suggest using aluminum so as to make the leg lighter. His design would wait until 1912, when Marcel Desoutter, a famous English aviator, lost his leg in an airplane accident, and made the first aluminum prosthesis with the help of his brother Charles, an engineer.
All of this led to World War II. Veterans returning from overseas were torn apart. World War II was famous for its use of artillery and explosives. Infections, while better understood, still weren’t completely unheard of. Amputations were sometimes still necessary as lifesaving measures. The problem was when they got back no advancements had been made. Nobody wanted to walk around with a hook hand so the veterans demanded reform. Uncle Sam responded in kind, (too bad he doesn’t seem to listen anymore…)
Thus the prosthetics industry was born. Modern advancements in the industry have led to lightweight metals, composite materials, and plastics being used in prosthetic devices. The new limbs simulate normal body parts much better and in some instances are even crafted to look completely normal.
From a fake big toe in Egypt, to battlefield amputations in French and European wars, prosthetics have played a major role in human function for centuries. With military funding behind it we have seen some of the greatest advances in history. Let’s take a look at some of these awesome technological leaps we’ve made.

The 6 Million Dollar Man


Below the knee, above the knee, under the elbow, maybe you just need a hand? Perhaps a foot? Prosthetics come in all shapes, sizes, colors, functions, and types these days. But let me ask you this. What’s the first thing that comes to mind when someone mentions prosthetics? It’s a fake limb of sorts isn’t it? Well that isn’t necessarily always the case.
When I did my analysis of how close we were to making the Master Chief from Halo’s suit I did a brief discussion of the HAL (Hybrid Assistive Limb). You can find that blog here. The original plan for HAL was to be used to help paraplegics walk again but they quickly discovered it had vital use as a super-suit of sorts and became implemented for use in disaster cleanup and rescue.
The way the suit works is pretty incredible. Here is the description, directly from Cyberdyne’s website:

§  When a person attempts to move, nerve signals are sent from the brain to the muscles via motoneurons, moving the musculoskeletal system as a consequence. At this moment, very weak biosignals can be detected on the surface of the skin. "HAL" catches these signals through a sensor attached on the skin of the wearer. Based on the signals obtained, the power unit is controlled to move the joint in unison with the wearer's muscle movement, enabling HAL to support the wearer's daily activities. This is what we call a 'voluntary control system' that provides movement interpreting the wearer's intention from the biosignals in advance of the actual movement. It’s not only a 'voluntary control system' "HAL" has, but also a 'robotic autonomous control system' that provides human-like movement based on a robotic system which integrally work together with the 'autonomous control system'. "HAL" is the world's first cyborg-type robot controlled by this unique Hybrid System.
§        "HAL" is expected to be applied in various fields such as rehabilitation support and physical training support in medical field, ADL support for disabled people, heavy labor support at factories, and rescue support at disaster sites, as well as in the entertainment field.


It’s not just power suits like HAL making the headlines. Remember our discussion on 3D and 4D printing and how that works? If not you can catch up here. Well if you combine that technology with a little clever bioengineering, voila! 3-Dimensional Bio-printing! What is this useful for you ask? Take a look at the image below.


Now, imagine that was you. You just had that unsightly tumor removed and a gaping hole was left on your face. Sure, you can cover it with an eye patch but after a while the pirate jokes get old. Now with the aide of this new technology that ridicule is a thing of the past. While the eye may not function, the cosmetic confidence that comes along with these types of prostheses is still worth the effort to develop them.
The way that bio-printing works is instead of loading a non-organic base material into the printer, an organic material (DNA, proteins, so on so forth) are added into the machine. It doesn’t just stop with the development of synthetic skin and bone. Doctors are convinced that this machinery will lead them to the development of working body parts and organs!
It’s also important to note that brain chips have also come a long way since their early development. New tests have shown that they can repair damaged areas in animals and allow them to resume functions once thought impossible. This will be particularly useful for soldiers suffering from traumatic blast injuries and patients that have undergone a stroke or had a tumor removed that damaged a part of the brain.
With more and more soldiers coming home disfigured every day and cancer scarring so many individuals with its horrifying blight further development of this technology is necessary. After all, (and this is especially true in the case of soldiers) doesn’t everyone deserve the chance to feel normal?

-       Ryan Sanders

Thank you for reading! As always feel free to share this around on Facebook and Twitter! For further reading on prosthetic devices and their history, follow any of the links below. Happy learning!









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