War has been described as representing the absolute worst in humanity. At the same time, throughout history, it has been the engine for some of the most beneficial advances in science, technology, and medicine.
The ongoing war in Southwest Asia is no exception. U.S. and allied warfighters have benefited from a new generation of armor – both personal and vehicle – along with enhanced medical care from the point of injury to rapid evacuation to full surgical care within the “golden hour.” Combined, they have led to the lowest killed-in-action ratio of any war in history, with warfighters routinely surviving attacks that would have been fatal on any previous battlefield.
But while body armor has significantly reduced potentially fatal wounds to the torso, the extensive use of improvised explosive devices (IEDs) also has increased the number of amputations as a percentage of wounds. Although still a small number – about 1,000 from a decade of combat – compared to the number of civilian amputations each year resulting from accidents or disease, such as diabetes, it has spurred an unprecedented level of R&D and technology advances in prosthetics.
“When you think about the amount of resources that have gone into care for those 1,000 military personnel, it is tremendous,” noted Joseph Miller, the VA’s national director for Orthotic & Prosthetic Services. “That includes wonderful rehab facilities designed to serve a number of injuries, but primarily amputation, $100 million or so to make a new prosthetic arm at DARPA [Defense Advanced Research Projects Agency], congressional dollars going for new products specifically based on DoD [Department of Defense] and VA recommendations, etc.
“There have been huge strides in technology and in collaboration between VA, DoD, other government agencies, and the private sector. There also have been strides in the application of these technologies, in training methodologies, and in the understanding of what veterans will be doing in the future, both active duty and civilian.”
When casualties first began returning from Southwest Asia, the technology of prosthetics was largely in the materials used to construct them. But Miller, at that time the head of prosthetics at Walter Reed Army Medical Center, soon found himself at the center of a sweeping technology revolution.
“There were only one or two microprocessor knees on the market [in 2003] and they were considered experimental, so very few received them. At Walter Reed, we convened a conference asking if industry could provide data to show those could be used for newly injured patients, not just those who had had prosthetic legs for many years. They could not answer that, so we decided to go ahead and use them that way, making myoelectrics the first choice,” he recalled.
“That change in care, by DoD and Walter Reed, was based on the injured warfighters being tactical athletes, and we had to look at them from that sports model. So we took into account the patients’ goals and needs in determining the rehabilitation process, which was a big change.”
An Army Reserve captain in the Medical Services Corps, Miller also deployed to Iraq for six months in 2006, gaining frontline knowledge about warfighter attitudes toward amputation and prosthetics. Back in civilian life, as part of his work at Walter Reed, he traveled around the globe, reviewing what kinds of prosthetic and orthotic rehabilitation programs other nations were employing.
One major lesson learned began with a difference in warfighter attitude that led to significant changes in the look, feel, and application of prosthetic feet and legs.
“The acceptance of the prosthetics and cosmetic appearance have changed. In years past, including geriatric patients, the goal was to make the new leg look as much as possible like the other, so it was not noticed so much. But with the new OIF/OEF [Operation Iraqi Freedom/Operation Enduring Freedom] amputees, the prosthetic is not covered; some are even multi-colored or have special patterns, such as their unit insignia. It’s almost a badge of honor – they want to talk about it,” he said. “For lower extremities at Walter Reed, I don’t think more than one or two patients covered them.
“For upper [extremities], there is a greater incidence of covering. But the quality of coverings today is tremendous, extremely lifelike. We could even take a picture they might have of an old tattoo and embed that into the silicon cover. So where covers are wanted, it is at the extreme high end of cosmetics – movie industry quality.”
Some new prosthetic feet with graphite pylons have a “futuristic” appearance many patients like, including a variety of colors from the sockets. So instead of using pigments to match skin tone, the patient may opt to show off the technology or select a spandex-type material with a design of their choice.
A record number of amputees are rejecting medical discharge and returning to duty – some to combat – and even those who do leave the service remain intent on leading physically active lives. As a result, rehabilitation, while longer and more intensive than what private insurance will cover for civilians, also tends to be approached with greater commitment, Miller added. And because this generation of young warfighters is comfortable with technology, they want access to a wider range of prosthetics and capabilities, especially those going back on active duty.
“As part of the rehabilitation process, they are exposed to a number of sporting activities they may not have been involved with prior to their injury. Those put demands on them and the prosthetics, which have led to the development of specific use prosthetics, from skiing and running to jumping out of airplanes,” he said. “If you look at young civilian patients, they may not be as fit as the military members or have the same activity level experience, but they share the desire for those same technologies.
“When you get to patients 40 and older, they still want to be active and try different things, maybe not as aggressively, but the desire is there. The VA has to offer the same services to all its veterans, regardless of age or injury, so it is up to the clinical team to evaluate the patient and the technology. That means they may provide a powered knee to both a 75-year-old Korean War veteran and a 25-year-old soldier back from Afghanistan. But the technology will have different benefits to those different populations.”
The greatest advances have been made in prosthetic feet and legs, both because there are far more lower-extremity amputations than upper and because the greater range of motion, fine movement, and sensitivity to touch and temperature make arms and hands extremely difficult to replicate.
“In hands, individually articulating fingers are the latest development, with hands programmable for different pinch modes, grasps, etc., including the ability to sense a required grasp. What is not yet commercially available is a sense of touch, even hot and cold – propiosceptic feedback – so a prosthetic hand can’t tell what it feels,” said John Fergason, chief prosthetist at Brooke Army Medical Center’s rehabilitation facility, the Center for the Intrepid, in San Antonio, Texas.
“Arms and hands require better control systems, decreased weight, better range of motion, and the ability to accomplish fine motor tasks – but also must be durable enough to accomplish gross motor tasks. That is a tall order in the upper extremities. DARPA has been addressing that with experiments in neural control, but that has not yet made it to the clinical level.”
DARPA’s prosthetics R&D involves a wide range of requirements common to both upper and lower extremities – power (in terms of action), ease of use, durability, weather-proofing, and better energy sources, so the user does not have to plug it into a wall socket every night.
“Basically, they want devices that allow an injured servicemember to return to duty, which means something rugged, that can work in remote locations and adverse weather,” he said.
While the latest designs and materials used in prosthetic feet and legs have allowed amputees to fully engage in activities that would have seemed impossible to previous generations – playing basketball, riding a bike, climbing, etc. – incorporating microprocessors and powered joints is moving overall capabilities to an even higher level.
“Ankles with battery-powered joints will produce powered push-off rather than just relying on stored energy for dynamic response. That’s really been the big missing biomechanical piece. You can store and release energy in a responsive fashion with carbon-graphite, but there really hasn’t been a reliable way to produce power until now,” Fergason said. “The prosthetic will be a bit bigger and heavier than what we have been using [4.5 pounds versus 2 or 3], but if I have an artificial joint doing the powered push-off, the system won’t feel as heavy because I’m not doing all the work myself.”
There also are limitations based on the type of amputation, he added: “To use this technology, the amputation needs about 9 inches of clearance between the end of the limb and the floor. So if the amputation is right at the ankle, it wouldn’t work.”
The only actively powered microprocessor-controlled prosthetic ankle and foot currently available is the PowerFoot One. A self-contained robotic system, it incorporates two powerful microprocessors and six environmental sensors to evaluate and adjust ankle position, stiffness, damping, and power thousands of times a second, according to its creators. Control algorithms generate human-like force while traversing level ground, slopes, and stairs, providing active amputees with near-normal gait and lower energy expenditure compared to state-of-the-art passive prosthetics.
PowerFoot One was created by iWalk, founded in August 2006 by researchers and engineers from MIT and Dartmouth. Based on years of research in biomechanics, bio-energetics, materials science, and joint control at MIT’s Media Lab and core technologies licensed from MIT, the PowerFoot One is partially funded by the VA and the Army Telemedicine and Advanced Technology Research Center (TATRC).
“By power, we mean powered plane flexion, which basically replaces the lost musculature of the calf, which helps launch you forward and has real-time gait recognition or terrain logic, so it knows where it is in space,” Shane Namack, iWalk’s vice president for sales, explained. “The PowerFoot works with the body, so the more the individual puts into it, the more return he gets. It also minimizes energy transfer from one step to the next
“Most prosthetic devices take weeks or months to get used to, but an individual can get acclimated to the PowerFoot in half a day; it just becomes part of their lives, learning from the users and adapting to their movements. With biomimetics [a mechanical device that imitates a natural process], we don’t want an acclimation period; we’re looking for metabolic augmentation and an efficiency equal to the natural foot.”
Company founder and chief scientific officer Dr. Hugh Herr is a bilateral amputee and currently the only person walking on two PowerFoot One prosthetics, Namack added: “We’re concentrating on single amputees until we are satisfied with all the results, but it should be more efficient for bilaterals, as well.”
DoD conducted clinical research fittings of the device during the summer of 2010, with iWalk planning to make it available across the DoD and VA medical care systems and a limited number of civilian facilities by the end of the year.
For active duty, National Guard, and Reserve personnel, and veterans, regardless of when or how they lost a foot or leg, powered and microprocessor-controlled prosthetics will be made available, without charge, based on healthcare provider evaluations of the actual benefits they bring to each individual.
As to powered knees, Fergason said, “there are some commercially available now, but they are expensive, very heavy, noisy, and have other limitations. A lot of work is going into that technology, however, so powered ankle and knee joints should become standard in a few years. Even then, the two would have to be properly interfaced to work in tandem or you would have an inefficient ambulation pattern.”
Even without powered joints, the use of microprocessors has greatly improved the capabilities of lower limb replacements.
“The microprocessor knee has brought significant benefits in walking speed, reduced incidents of falls – which is a big issue, because injuries from falls often are the cause of long-term problems – and stability on stairs and hills, both inclines and declines. So there is a much reduced incidence of uncontrolled knee flexion – another way of saying fall,” he explained. “The VA, DoD, and private health care have documented those.
“But they can’t be submerged in water and must be maintained, which can be very expensive once the warranty expires; that depends on the knee, but the standard is two or three years, with the option of buying an extension to five. Based on a lot of repairs I’ve seen, that’s not a bad idea. Then again, five years is a long time for using a particular component, due to wear and tear by an active user, but also because technology is advancing so quickly that today’s exciting technology is likely to be overwhelmed tomorrow.”
The nation’s commitment to provide lifelong care to its wounded warriors means DoD and the VA look at every new technology and capability that appears to have utility for amputees – and, if proven, make any or all of those available to any service member or veteran who wants them. But it is a process that involves more that just providing a new prosthetic.
“What we struggle with when new technologies come out are the appropriate populations for that technology. Being new does not necessarily mean it will offer any new advantages for any given individual, but we are almost required to buy them because they are new and advanced,” Miller said. “But what does that mean?
“Powered knees were the first that allowed propulsion for the patient, which is great, but there are age group, cognitive considerations, and physical capabilities that haven’t yet been researched. That’s our struggle – defining the appropriate population and determining if the outcomes of this technology are beneficial. And why we should prescribe a powered knee to one group rather than another.”
Just as the rapid advances in prosthetic technologies have provided improved capability to amputees, they also have been part of an ongoing evolution in the profession itself, from academics to how industry views its role in the future. According to Miller, staying on the front end of the curve in all of those are challenges that must be met across all elements.
“This profession has progressed from a low-end shop or manufacturing base to a clinical base, where we are now, to a knowledge base in the future. On the academic side, the field is moving from bachelor’s to master’s for initial entry – and that’s good – but if the future involves cortical or internal prosthetics, the profession currently is not trained to handle that. And our universities are not dealing with that because it is not currently a requirement. But it will be and that should be built in,” he concluded. “At some point, prosthetics may require an M.D.
“Industry also needs to work much harder at outcomes and identifying technologies and their appropriate populations. But probably the most important challenge is the whole industry is built on an outdated reimbursement model, which continues to be based on product. The profession needs to have a meeting of minds with itself and determine if that will continue or if cost will be based on service and knowledge. And that is a huge question, because tweaking that would change everything, from how industry prices its products to rehabilitation programs to the availability of prosthetics for patients.”
This article was first published in The Year in Veterans Affairs and Military Medicine: 2010-2011 Edition.