World’s first ‘feel­ing’ leg pros­the­sis of­fers new sense of hope to am­putees


The world’s first ar­ti­fi­cial leg ca­pa­ble of sim­u­lat­ing the feel­ings of a real limb and fight­ing phantom pain was un­veiled by re­searchers in Vi­enna on Mon­day.

The in­no­va­tion is the re­sult of a two-fold process, de­vel­oped by Pro­fes­sor Hu­bert Eg­ger at the Uni­ver­sity of Linz in north­ern Aus­tria.

Sur­geons first rewired re­main­ing foot nerve end­ings from a pa­tient’s stump to healthy tis­sue in the thigh, plac­ing them close to the skin sur­face.

Six sen­sors were then fit­ted to the foot sole of a light­weight pros­the­sis, and linked to so-called stim­u­la­tors in­side the shaft where the stump sits.

“It’s like a sec­ond lease of life, like be­ing re­born,” Aus­trian am­putee Wolf­gang Rang­ger, told AFP ahead of Mon­day’s me­dia launch.

The for­mer teacher, who lost his right leg in 2007 af­ter suf­fer­ing a blood clot caused by a cere­bral stroke, has spent the last six months testing the new pros­the­sis.

“It feels like I have a foot again. I no longer slip on ice and I can tell whether I walk on gravel, con­crete, grass or sand. I can even feel small stones,” he said.

The 54- year- old also runs, cy­cles and goes climb­ing. When he moves, the limp is barely no­tice­able.

Ev­ery time Rang­ger takes a step or ap­plies pres­sure, the small sen­sor de­vices send sig­nals to the brain.

“In a healthy foot, skin re­cep­tors carry out this func­tion but they are ob­vi­ously miss­ing here. How­ever, the in­for­ma­tion con­duc­tors — the nerves — are still present, they’re just not be­ing stim­u­lated,” Eg­ger said.

“The sen­sors tell the brain there is a foot and the wearer has the im­pres­sion that it rolls off the ground when he walks. All things con­sid­ered, the pro­ce­dure is a very sim­ple one given the re­sults.”

This is not the first time the Aus­trian sci­en­tist has caused a stir with his re­search.

In 2010, he pre­sented a mind­con­trolled pros­thetic arm, which the user di­rected with mo­tor neu­rons pre­vi­ously con­nected to the lost limb.

For the ar­ti­fi­cial leg, the prin­ci­ple re­mains the same ex­cept that the process works in re­verse: in­for­ma­tion is guided from the proth­e­sis to the brain, rather than the other way around. No More Mor­phine

In ad­di­tion to in­creas­ing bal­ance and safety, the pros­the­sis pro­vides an­other re­mark­able func­tion: it has helped erad­i­cate the ex­cru­ci­at­ing pain Rang­ger had ex­pe­ri­enced for years fol­low­ing his am­pu­ta­tion.

“I was barely able to walk with a con­ven­tional pros­the­sis, didn’t sleep for more than two hours a night and needed mor­phine to make it through the day,” he re­called.

But within days of un­der­go­ing the op­er­a­tion last Oc­to­ber, the pain van­ished.

As Eg­ger points out, phantom pain oc­curs be­cause the brain gets in­creas­ingly sen­si­tive as it seeks in­for­ma­tion about the miss­ing limb.

“Plus the am­pu­ta­tion is of­ten tied to a trau­matic ex­pe­ri­ence like an ac­ci­dent or ill­ness, and the mind keeps re­liv­ing th­ese mem­o­ries,” he noted.

The ad­van­tage of the “feel­ing pros­the­sis” is that the brain once again re­ceives real data and can stop its fran­tic search.

“Rang­ger is a very dif­fer­ent per­son now to the one I met in 2012,” Eg­ger said.

The two men were in­tro­duced to each other at a sup­port group for am­putees.

“It struck me that he never laughed and he had th­ese dark rings un­der his eyes. It was aw­ful.”

Im­por­tantly, post-surgery re­cov­ery is quick and there are no known health dan­gers as­so­ci­ated with the in­ter­ven­tion, he added.

“The only risk is that the nerves don’t re­con­nect prop­erly and the feel­ings fail to re­turn,” he said.

With the new tech­nol­ogy ready, Eg­ger now hopes that small com­pa­nies will join his ven­ture and start build­ing the pros­the­sis to help bring down the mar­ket price.

At the mo­ment, a high-tech foot model costs be­tween 10,000 eu­ros (US$11,240) and 30,000 eu­ros.

Eg­ger be­lieves his lat­est project could vastly im­prove qual­ity of life for am­putees, in­clud­ing in de­vel­op­ing coun­tries.

“Peo­ple with am­pu­ta­tions aren’t pa­tients in the tra­di­tional sense, they aren’t sick — they’re just miss­ing a limb,” he said.

“By giv­ing them back mo­bil­ity, they also re­gain their in­de­pen­dence and are able to rein­te­grate into so­ci­ety. That’s what I work for.”

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