One of the proponents of modern warfare is that during times of war, the enemy can make more of an impact on day-to-day fighting not by the number of kills it notches, but by the amount of peripheral damage that is incurred. Think about it — once you’re dead that’s it. But if you’re injured — if a soldier takes some shrapnel by stepping on a mine or loses a finger or a limb or worse, then not only is that soldier out of action, but now you have employed the use of medics and trucks to carry the wounded and helicopters and hospitals and who knows what else. Injuries slow things down. It forces the military forces that suffer injuries to stop and re-adjust. And doing that costs time and money and more soldiers.
Nowhere has this been more evident than in the war in Iraq. According to statistics from the New England Journal of Medicine (www.nejm.org), for every soldier killed in Iraq, nine others have been wounded and survived, that’s the highest rate of any war in U.S. history. The irony — say doctors — is that we’re saving more lives but losing more limbs. In other words, percentage-wise, more soldiers in Iraq are surviving their wounds than in Vietnam for example, but more of them are coming back asamputees — 370 at last count.
To take the argument one step further, it’s because of the increase of war-related amputees that more advances are coming about much more quickly than perhaps if the war in Iraq wasn’t going on. I’m not sure that’s the type of impetus you want to have for technological advancement, but none-the-less, some serious advances are being made in the field of prosthetics and in large part it’s due to the war. Let’s take a look at what’s being used now and what is in the works for the future:
1) The biggest advancement — according to www.discoveriesinmedicine.com — and what has literally revolutionized prosthetics is what is called the C-Leg. The C-Leg fits into a socket and uses a hydraulic piston to analyze the user’s gait and speed while continuously adjusting resistance. The C-Leg prosthetic (see photo) is helping to blur the line between man and machine. The $40,000 lithium-ion (30 hours of juice) powered C-Leg has a “computer chip” in the knee which reads how fast the person is walking at a rate of 50 times a second faster than previous models.
2) Dynamic response feet with plastic springs: carbon-fiber composites are increasingly being used in artificiallimbs, largely because of their superior strength to weight characteristics.According to www.abledata.com one of the most successful innovators has been the Flex-Foot (see photo) — which is widelyacknowledged to be the most effective at storing and releasingenergy during walking and, in particular, recreational and competitivesports activities.
3) Shock absorbing mechanisms to reduce impact forces: the Re-Flex shin-foot (see photo) couples a spring-loaded shock absorber with the dynamic response foot.Studies in walking and gait have confirmed that this type of componentimproves the biomechanical performance of artificial limbs.
4) Modern industrial fabrication — particularly with injection-molded plastics — can create lightweight, low cost components withsufficient function for limited walking.
Meanwhile, the Department of Veterans Affairs (www.va.gov) earmarked nearly 8 million dollars in 2005 to create the Center for Restorative and Regenerative Medicine — dedicated to researching cutting-edge technologies to help make prosthetics more effective. For example, artificial knees and ankles will be sown with a slew of sensors for situational awareness and feedback control. A wireless microchip called a Bion will provide connection between the nerve endings in the leg and the artificial knee and ankle. Information must be fed back to other parts of the artificial leg, and ultimately will be driven by signals from the central nervous system. It must also be predictive, not just responding to the first step, but changing the leg to anticipate it.
According to the British Medical Journal (www.bmj.com), the process of installing and networking sensors in an artificial limb is difficult. It requires a researcher to match the pattern of electromyogram (EMG) signals to a specific behavior. EMG then records the electrical activity of muscles. When muscles are active, they produce an electrical current that are proportional to the level of the activity. But matching electrical signals to real-life movements is complex since there are so many variables at work.
Another avenue of note in prosthetic research and development involves the International Committee of the Red Cross (www.icrc.org) which has established an initiative to produce low cost polypropylene plastic prostheses,made by unskilled local workers, for areas where conflict or environmentalcatastrophes have resulted in large numbers of traumatic amputations. These devices are well accepted clinically,although some problems have been reported with their durability.
In closing, there are about 1.8 million amputees in the world, and that number pales in comparison to…say…the number of individuals stricken with cancer or AIDS. As a result the amount of funding for research and development remains relative the amount of amputees. A high-profile crisis like a war certainly shines a spotlight on the need for more high-tech prosthetics and indeed more attention is being given to the advancement of artificial limbs than ever before.