Prosthetic devices have existed for thousands of years. Some date to the Great Pyramids. In the last few decades, they’ve become far less wieldy and easier to use. One reason is the materials from which they’re made.
The ancient Egyptians were masters of more than embalming. While their prosthetic limbs were made of fiber and existed largely to create a sense of wholeness, a prosthetic toe on a mummy appears to have been functional. Modern designers have sought prosthetic materials that enhance both function and aesthetics.
Legs
The earliest artificial leg dates to around 300 B.C. in Italy. It had a wooden core and was also made of iron and bronze. The stereotypical wooden peg leg dates to the Dark Ages. American literature of the 19th century contained stark images of peg legs straight out of Moby Dick. By the next century, most artificial legs were made of wood, steel, copper and iron.
The basic technology in modern leg prostheses come from the 16th century, when a French surgeon designed a kneeling peg leg and foot device with a fixed position, knee lock control and adjustable harness. Civil War amputees commonly used a prosthesis made from whittled barrel staves.
After World War II, the military services were leaders in advances in prosthetic technology. Today’s legs return amputees to the lifestyle they enjoyed rather than just providing acceptable technology or a good cosmetic appearance.
These legs are lightweight thanks to plastic, aluminum and composite components. Many are molded to patients and contain microprocessors, computer chips and robotics for maximum functionality.
Knees
The modern artificial knee dates to 1968. The materials used have changed many times over the years due to the need to bear weight.
Throughout the 1970s, common materials included Teflon®, stainless steel and cobalt-chromium alloy. During the next two decades, the most popular construction involved ultra-high-molecular-weight polyethylene and cobalt-chromium. Use of polyethylene reduced friction against metallic surfaces.
The construction of current artificial knees depends in part on the type of knee replacement the patient needs. Manufacturers use a variety of metals and metal alloys. Among the most common are steel, stainless steel, titanium, cobalt and chrome.
Hands
The earliest prosthetic hands were made of wood and leather and had no functionality. By the rise of the Roman Empire, a combination of wood and metal had supplanted leather use. An iron hand linked to the general Marcus Sergius had very limited functionality.
Until the 16th century, most people who needed artificial hands used hooks. Only the wealthy obtained hand-like prostheses. By the end of the century, one type of hand was made of iron and had a system of springs and catchers.
A Civil War inventor came up with a molded rubber hand, which was considered more resilient than using wood and steel. A spindle attached it to the end of an artificial forearm.
Russians developed the first functional moving hand in the 1960s. Many current prosthetic hands are technological wonders. Sounds, nerves and muscles can control movement. Silicone covers provide a very realistic skin appearance on lightweight devices that utilize a number of composite materials.
Nylon inside the glove of an artificial hand increases durability. Cosmetic touches include fingernails, fingerprints, veins and a natural skin tone.
Today’s patients have a growing number of choices when it comes to prosthetic devices. As designers incorporate new materials, the options will continue to grow.
