New Knee Helps Amputees Return to Front Lines

BETHESDA, Md. — A sophis­ti­cat­ed pros­thet­ic knee with a new­ly designed micro­proces­sor is giv­ing many wound­ed war­riors with above-the-knee ampu­ta­tions the chance to return to active duty, mil­i­tary med­ical offi­cials here report­ed.

Wound­ed war­riors who had such severe limb loss in the ear­ly days of the Iraq and Afghanistan wars were fit­ted with a pros­thet­ic, reha­bil­i­tat­ed and med­ical­ly retired in most cas­es, amputee ser­vices offi­cials at Wal­ter Reed Nation­al Mil­i­tary Med­ical Cen­ter said. That was before 2004, when the Defense Depart­ment con­tract­ed with a pros­thet­ics com­pa­ny to design a “mil­i­tary grade”

micro­proces­sor-con­trolled pros­thet­ic knee to return these skilled vet­er­ans to duty when pos­si­ble, offi­cials said.

As a result, troops who have returned to duty wear­ing the Geni­um X2 pros­thet­ic knee dur­ing the past three years include mem­bers of the Navy’s SEALS, the Army’s Gold­en Knights para­chute team and infantry­men on the front lines, said David Laufer, chief of orthotics and pros­thet­ics ser­vices.

“We want­ed to enable any wound­ed sol­dier who has the will­ing­ness and abil­i­ty to go back on active duty,” he said. “We’re not try­ing to force sol­diers, Marines or sailors to go back on active duty after an ampu­ta­tion. We want to give them the oppor­tu­ni­ty to stay on active duty, and not be lim­it­ed by their pros­the­ses.”

The impact of these ser­vice mem­bers return­ing to the com­bat the­ater is more far-reach­ing than the exten­sive skills and expe­ri­ence they bring with them, clin­ic staff mem­bers said, not­ing that oth­er ser­vice mem­bers can gain a new per­spec­tive on wound­ed war­riors when they fight side-by-side with those wear­ing the new­ly designed pros­thet­ic knee.

“They see them bring for­ward what they already know and real­ize they can do the jobs they were doing before they were injured,” said Charles Scov­ille, chief of amputee ser­vices in the med­ical center’s ortho­pe­dics and reha­bil­i­ta­tion depart­ment.

“They learn to respect [those wear­ing the pros­thet­ic knee], and real­ize, ‘He’s not going to hold us back or get us killed,’ ” he said. “It also shows them if they are injured, they will be tak­en care of.”

Laufer said the new devices are on back order, because the com­pa­ny that man­u­fac­tur­ers them can’t keep up with grow­ing demand.

One, the X2, was an instant hit when the first few patients got the oppor­tu­ni­ty to try it out as a pro­to­type three years ago, Scov­ille said. At the time, the next-gen­er­a­tion knee, the X3 that is sched­uled to debut this sum­mer, was still in the design phase.

“We were so impressed by the X2 pro­to­type,” Scov­ille said. “We told the com­pa­ny, ‘We need these now.’ ”

At first con­sid­ered “impos­si­ble” to design, the X2 has pro­vid­ed a new way of life for above-the-knee amputees, Scov­ille said. The new micro­proces­sor has five sen­sors, com­pared with the orig­i­nal C‑Leg, which had two, said Zachary Har­vey, a cer­ti­fied pros­thet­ic ortho­tist.

A com­bi­na­tion of gyro­scopes, accel­er­a­tors and hydraulics form the knee’s greater sta­bil­i­ty, mobil­i­ty and its ver­sa­til­i­ty by “rec­og­niz­ing” actions, Har­vey said.

Mul­ti­ple sen­sors rec­og­nize when the wear­er wants to sit down or go up and down ramps and stairs, he explained, all with­out being pre­set with a remote device, as required by for­mer tech­nol­o­gy.

Har­vey said the X2 is intu­itive to learn. “It feels nat­ur­al to walk on, in com­par­i­son to some oth­er knees,” he said.

The X2 also enables wear­ers to rapid­ly switch from a walk mode into a run with­out chang­ing set­tings, he said. “The X2 knee picks up on the change, kicks in and swings out a lit­tle faster into a run,” he explained.

In addi­tion, the X2 fea­tures a pro­tec­tive cov­er in the event of falls and oth­er minor acci­dents. “It’s a qual­i­ta­tive and quan­ti­ta­tive leap,” Laufer said, com­par­ing it to the two-sen­sor unit on the C‑Leg.

Marine Corps 1st Lt. James Byler, a 26-year-old infantry­man who was wound­ed in Afghanistan more than a year ago, said he got used to the X2 almost imme­di­ate­ly. A dou­ble amputee above the knees, Byler was fit­ted with a C‑Leg for sev­er­al months before receiv­ing an X2 for one leg and a pow­er knee on the oth­er leg for his own com­par­i­son.

Unlike the X2, the pow­er knee pro­pelled him for­ward and was com­pli­cat­ed because he had to focus on the knee, which was hard to do while walk­ing, he said.

When Byler went to the X2 mod­el on both knees, “the feel­ing was pret­ty imme­di­ate,” he said.

“I don’t think there’s any knee that com­pares to the X2,” Byler added. “It feels more nat­ur­al than the oth­ers.”

The effect on his reha­bil­i­ta­tion, Byler said, has been dra­mat­ic.

“It was only recent­ly that guys like me with the real­ly high ampu­ta­tions [real­ized] we could walk at all,” he said. “It took a lot of time and effort just to get up and walk.”

Byler said he’s decid­ed to retire from the mil­i­tary, because as a dou­ble above-the-knee amputee, he does­n’t want to be a lia­bil­i­ty. But that does­n’t stop him and some of his fel­low patients from putting on their X2 knees pros­the­ses to vis­it new­ly injured patients who are bed­bound. He and his friends tell the new patients it’s the X2 they want to get, and not any­thing else.

“I can walk on the X2 and not even think about it,” Byler said. “That’s the goal.”

U.S. Depart­ment of Defense
Office of the Assis­tant Sec­re­tary of Defense (Pub­lic Affairs)

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