Prosthesis: Combining Biology, Design, and Marketing

Those that are missing limbs know that each piece of our body is merely one part of a complicated network that connects every system and organ together, allowing us to walk, write, and scratch our nose without giving it a second thought. Increasing mobility and function, therefore, is not just a matter of replacing the missing limb; it’s also a matter of replacing the synergy between the limb and various systems of the body, a connection that is constantly being redefined. The mysteries of the human body might never be entirely understood, but recent innovations in the field of prosthetics have shown that bio-engineers working in the field of prosthetics have come closer than anyone to comprehending the complex ways that parts of the body communicate with one another.

The Mind-Body Connection: New Frontiers in Bionic Technology

The latest “bionic” limbs to hit the market would seem adequate in the pages of a comic book. These prosthetics are pushing the boundaries on looks and functionality by responding to the individual wearer and environment, allowing more maneuverability than previous prosthetics. With myoelectric technology—typically found in prosthetic arms, hands, and fingers—electronic sensors detect muscle and nerve activity in the wearer to produce movement. Because these prosthetics are electrical rather than mechanical, they are less bulky and can be covered with realistic-looking skin. One such product is the i-limb Ultra from the Scotland-based company Touch Bionics, whose five-fingered structure allows its wearer to zip up a coat, grip a glass of water, and use a pincer grasp to hold small objects. A software program personalizes the limb control for each individual user and also helps train the user to master the muscle movement needed to control the limb.

Advancements in microprocessor technology have allowed greater communication between the artificial limbs, their wearers, and the environment, resulting in prosthetic knees, legs, and feet that respond to the terrain and allow for more natural movement. Until recently, however, most lower leg replacements put stress on the rest of the body and decreased mobility for their users. IWalk’s BioM, created by a team led by MIT’s Dr. Hugh Herr, was funded in partnership with the U.S. Department of Veterans Affairs to help war-injured soldiers. This prosthetic lower leg has “powered plantar flexion” to simulate the work that the calf muscles, Achilles tendons, and ankles do to propel us forward as we walk, thereby lessening the stress on the rest of the muscles and joints

Prosthetics for Athletes

The Iceland-headquartered company Ossur has made recent news for their collaboration with Nike to produce the Flex-Run with a removable, running-specific sole. Designed specifically for distance running, the Flex-Run was inspired by the triathlete Sarah Reinertsen. Ossur has also recently gained headlines for another of its running prosthetics, the Flex-Foot Cheetah, the sprinting foot of choice for Oscar Pistorius, the South African runner who has his sights on the 2012 London Olympics. A court recently ruled that the Flex-Foot does not give Pistorius a competitive advantage over his able-bodied competitors. Neither the Flex-Foot Cheetah nor the Flex-Run are bionic feet. They are described as “passive-elastic springs” that are meant to imitate biological legs in the act of running.

Innovations in Photography and Printing

Touch Bionics, the firm responsible for creating the iLimb Ultra, is also a leader in creating passive prosthetics, which are used more for their aesthetics than their utility. Through a scanning device called Living Image, the remaining limb on a patient is scanned and recreated down to the last freckle, wrinkle, and hair. The result is an incredibly realistic-looking, perfectly matched prosthetic that can be created very quickly.

Another similar use for scanning technology is pairing it with 3-D printing to create prosthetic coverings that look like skin. Bespoke Innovations is a company that utilizes this technology to create “fairings” that are specific to patients’ requirements. 3-D printing is the also the inspiration behind a prize-winning idea by a University of Wisconsin student. Inspired by victims of the Southeast Asian Tsunami, he set out to create a functional prosthetic hand that could be cheaply and easily made for use in developing countries. By eliminating the manufacturing step and utilizing 3-D printing technology, he says his resulting design, Manu Print, could be made for about $20.

The Future of Prosthetics

As bioengineers look toward the future of prosthetics, the emphasis will be on making even more connections between the missing limbs and the brain. Under contract with the U.S. Defense Advanced Research Projects Agency, John Hopkins University’s Applied Physics Laboratory is currently conducting trials that place electrodes in the brains of spinal-cord injury amputees, allowing them to control a bionic arm with the power of their brain. The next step would be reversing the process, sending the signal back from an object, through the fingers, and to the brain, essentially restoring a patient’s sense of touch. Although these projects are still under development, it’s clear that recent advancements by scientists and engineers working in the field of prosthetics have given new life to those living without a leg, foot, or hand, turning what was once a devastating diagnosis into an opportunity to step into the future.

Sources: