Prosthetics: A Step Ahead
An unprecedented surge in science and technology has enabled hundreds of service member amputees to return to service.
In Iraq and Afghanistan, where improvised explosive devices (IEDs) have often been insurgents’ weapons of choice, the Department of Defense (DoD) estimates that more than 1,600 service members have lost limbs since the start of the wars in 2001 – and, according to the Armed Forces Health Surveillance Center, 2011 was the worst year on record, with 240 deployed servicemen and women suffering at least one arm or leg amputation. Of all the amputations performed on service members deployed to Iraq and Afghanistan, about 82 percent have involved injuries to a lower limb.
In the early years of the Iraq and Afghanistan conflicts, wounded warriors with severe limb loss were fitted with prosthetics, rehabilitated, and medically retired. Prosthetics was largely the purview of the Veterans Health Administration (VHA), that, as the health care branch of the Department of Veterans Affairs (VA), was charged with helping these veterans adjust and thrive as civilian amputees.
Today, the VA and its partners still play a leading role in prosthetics development, but the effort has received considerable assistance from the DoD since 2004, when the Pentagon contracted with a prosthetics company to design a “military-grade” prosthetic knee that could enable skilled and capable service members to return to duty whenever possible.
According to statistics made available by the Pentagon in the spring of 2012, these efforts are beginning to pay off for military personnel who want to return to service and earn a paycheck: More than 300 deployed service members who have suffered the loss of a limb have returned to active duty – and of those, more than 50 returned to Iraq or Afghanistan.
Such numbers would not have seemed possible even five years ago, but dual VA/Pentagon backing seems to have unleashed a torrent of innovation in the field of prosthetics, arguably advancing the field more in the last decade than in the previous 50 years.
Propelled by Intuition
Around 200 to 250 patients are fitted with prosthetic limbs each month at Walter Reed National Military Medical Center in Bethesda, Md., and they are learning to expect more than service members might have a decade ago. With the passive prosthetic technologies then available to most military members, lower limb amputees – particularly those with above-the-knee amputations – could expect very little in terms of mobility or even comfort. Even with the most advanced mechanical prosthesis, simple activities such as walking uphill, downhill, or backward – or even leaning against a wall, which requires knee and ankle strength – were difficult and often impossible. For unilateral amputees, the effort of shifting one’s body weight onto the intact leg often caused back and hip pain.
The C-leg®, introduced by the Otto Bock Corporation in the late 1990s, set a new standard for lower limb prosthetics. A microprocessor, receiving signals from two sensors on the leg, calculated the amount of resistance needed, and relayed that information to hydraulic cylinders that controlled the flexion of the knee. The hydraulics enabled a smoother gait and the ability to move in more than one direction.
With DoD’s backing, Otto Bock introduced a more sophisticated knee in 2009, the X2, an autoadaptive prosthetic that combines microprocessors, sensors, an accelerometer, and a gyroscope to vary hydraulic resistance to match a patient’s different gaits. Equipped with five sensors, the X2 is the first prosthetic knee to enable users to run forward and backward, walk uphill, and climb stairs foot over foot. The sensors automatically recognize when the wearer wants to sit down, stand up, step over an object, climb, or descend, offering greater range of motion and a more balanced distribution of weight between the prosthetic and intact legs.
The X2 prototype was tested by 36 wounded warriors with above-the-knee amputations in 2010. At first available only to veterans wounded in Iraq and Afghanistan, the X2 was recently made available to other veteran amputees, and promises to help other veterans who have lost legs to accidents or disease.