As of 2008, there were nearly 2 million Americans living with some form of limb loss according to statistics collected by the Amputee Coalition. Just over half of all limb amputations are the result of vascular disease, such as diabetes or peripheral arterial disease, while most of the remaining cases are caused by physical trauma; just under two percent of amputations are due to cancer. Every year, there are about 185,000 amputations which take place at medical facilities throughout the United States.
Limb loss is a condition which will likely affect a greater number of Americans in the years to come. A 2008 paper published by the National Institutes of Health predicted that the number of U.S. citizens will increase to 3.6 million by the year 2050, although that number could be reduced with advances in vascular disease treatments. Still, the NIH paper pegged the current rate of Americans living with limb loss at one out of every 190 citizens.
As we were contemplating a return to our evolution of technology series we were reminded that last December we published an article on the history of prosthetic limbs as Hugh Herr was about to receive the National Inventor of the year award from the Intellectual Property Owners (IPO). Herr, a double amputee, is the inventor of the world’s first bionic foot and calf system called the BiOM T2. In this earlier article we profiled bionics, focusing primarily on prosthetic limbs used to facilitate walking, and in some cases running.
Having spent time on bionic legs, we thought it might be interesting to take a look at bionic arms.
Bionic Arm Technology
Every region of the human body involves a great deal of intricate design which is incredibly difficult to reverse engineer. We may finally have a working bionic foot and calf system for lower-body amputees but functional replacements are also needed for those who have lost arms, eyes or other body parts. Today, we’re offering readers a glimpse into the current state of innovation for bionic arms to see how close our world is to fixing the loss of the fine motor skills enabled by the fingers and wrist of a the human hand.
There are a couple of aspects of arm and hand movement of which an effective bionics system needs to take into account. Unlike feet, hands are responsible for a dexterity in motion that can apply the force necessary to open a glass jar lid and yet be delicate enough to pick up a grape or raisin without crushing either. Our arms are also lighter in weight when compared proportionally with our legs, making large and heavy devices quite cumbersome to control.
The first decade of the 21st century saw some major advances in bionic arm technologies. The first half of that decade saw a team of researchers working together at the Rehabilitation Institute of Chicago’s Center for Bionic Medicine crafted a bionic arm for Jesse Sullivan, a high-power electrical lineman who lost both of his arms in May 2001 as the result of electrocution. The bionic arm is myoelectric, meaning that it is capable of detecting electrical signals generated by the muscles of the human body. To increase the control signals that can be detected from the body, doctors at RIC’s Neural Engineering Center for Artificial Limbs performed a series of nerve-muscle grafts to move nerves which used to travel to the arms into the chest muscles. By increasing the number of control signals that can be read from the patient’s nerves, doctors were able to outfit Sullivan with a working bionic arm that could be controlled naturally from his nerve impulses.
Myoelectric prosthetic arms hold a great deal of promise for those who are struggling with an amputated limb. A bionic arm recently developed by Japanese company Exiii utilizes myoelectrics as well as a user’s smartphone device to provide much of the computational power needed to process motion commands, obviating the expensive computational components that would otherwise need to be installed within the arm itself. This arm, which incorporates a body that is entirely 3D printed, was being sold for $300 per unit as of this March although it has yet to be released to a mass consumer audience.
However, myoelectric bionics are not the be all and end all that amputees will be seeking. The high cost of these devices, which can reach $100,000 or more for some models, is enough to put them out of reach for many consumers, although the health cost benefits of more advanced bionic prostheses have been argued. Many of these devices are also susceptible to water or dirt, making them poor options for farmers or outdoor recreation enthusiasts. There are also those who will argue that for all of the improvements that myoelectric models have seen over the past few years, low-tech models provide an effective solution if perhaps not the most cosmetically appealing one.
Dean Kamen and “Luke”
The U.S. Department of Defense has invested a great deal of money into the development of a comprehensive bionic arm that would restore mobility to wounded veterans. As of April 2009, a Defense Advanced Research Projects Agency (DARPA) initiative to develop a bionic arm had already spent $100 million and incorporated the work of 300 scientists in a project likened by one Army colonel to the Manhattan Project in terms of its size. The non-military applications of this technology has been cited by those involved in the project and in January 2012, a Minnesota man became the first American citizen to be outfitted with a bionic hand that had been developed by the military. In December 2013, a British corporal became the first wounded veteran from that country to receive and successfully operate a mind-controlled bionic arm.
The DARPA project is being pursued in conjunction with DEKA, a research and development company founded by Dean Kamen, inventor of the Segway scooter. The initial prototype of the DEKA Arm System, which is also known as “Luke,” was designed with 25 circuit boards, 10 motors and computing power equivalent to three PCs located in the unit’s wrist. The finished product provided mobility to users but weighed about nine pounds, which users found cumbersome over the course of 12 hours of daily use. A new support system was constructed for the arm which used a series of inflatable balloons to distribute the weight of the arm across the wearer’s shoulder. Last May, the DEKA Arm System was approved for commercialization by the U.S. Food and Drug Administration after being tested by dozens of armed forces veterans, 90 percent of whom were able to complete complex operations such as grasping coins or grabbing an egg without cracking the shell.
Another research institution which has been heavily involved with the development of bionic arms over the past few years is the John Hopkins University Applied Physics Laboratory. Unlike the DEKA “Luke” Arm which ends at the upper arm, the APL’s Modular Prosthetic Limbs have been developed to return mobility to upper-body amputees who have lost their shoulders. In December of last year, the APL’s bionic limbs were used to restore movement to a bilateral shoulder amputee who had lost both of his arms in an electrical accident 40 years earlier. Using a nerve grafting procedure known as targeted muscle innervation, which is similar to the RIC techniques described above, APL scientists were able to attach two bionic arms to the subject which are both thought-controlled.
The bundle of nerves near the shoulder which remain even after an arm is amputated has been the source of a lot of hope for the future of bionic arms. Medical teams at Brown University have even been able to implant sensors detecting neuron activities into the skulls of quadriplegics, creating a direct interface between the brain and the bionic limb to restore mobility even when spinal injury is involved.
3D printing techniques may also be a major boon to amputees who have a desire for the technology without the checking account to support a purchase, whether or not insurance applies. We’ve written on the cost-effective nature of 3D printing and additive manufacturing processes before here on IPWatchdog. In March of this year a team from Limbitless Solutions, a nonprofit organization operated by students of the University of Central Florida, created a myoelectric bionic arm for a 7-year-old boy born with a partially developed limb. Whereas a typical bionic prosthesis costs an average of $40,000, this working model cost less than $350 in materials.