Ath­lete knows how to bond with ar­ti­fi­cial leg

DEMM Engineering & Manufacturing - - PRODUCT WATCH -

When Mike Schulz lost con­trol of his sled dur­ing a snow­mo­bil­ing race in 2008, his foot hit the ground so hard that his knee hy­per­ex­tended almost all the way in the wrong di­rec­tion. His joint shat­tered and doc­tors had to am­pu­tate just above the knee.

Mike’s ca­reer was over un­less he could find a pros­thetic leg that could with­stand the im­pacts and stresses re­quired by his ex­treme sports. But noth­ing was avail­able. So Mike, whose two pas­sions are ath­letic com­pe­ti­tion and cre­ative en­gi­neer­ing and build­ing, de­cided to cre­ate his own pros­thetic leg.

Less than a year later, he had founded Biodapt, a company that man­u­fac­tures cut­ting-edge per­for­mance pros­thet­ics for ac­tion sports. His above-the-knee pros­thetic leg is used by ath­letes who com­pete in ex­treme sport­ing events such as the X Games, and am­a­teur adap­tive ath­letes who en­joy high-im­pact sports like skate­board­ing, horse­back rid­ing, cy­cling and ski­ing.

De­signed to with­stand ex­treme im­pacts and rep­e­ti­tion, the pros­thetic leg has two crit­i­cal joints. The Moto Knee uses a link­age cou­pled with an ad­justable pneu­matic shock ab­sorber from a moun­tain bike to reg­u­late the joint’s stiff­ness.

For sports re­quir­ing crit­i­cal toe pres­sure and an­kle ten­sion, the Versa Foot footan­kle assem­bly uses a sim­i­lar pneu­matic shock ab­sorber to em­u­late joint re­sis­tance.

The spe­cial­ized joints cre­ate an im­pact-resistant, wa­ter­proof pros­thetic that can be cus­tom­ized for a range of high-per­for­mance ac­tiv­i­ties. Schultz’s link­age sys­tem pro­vides re­sis­tance when the Moto Knee is f lexed as far as 135 de­grees – the po­si­tion of a leg squat­ting on a motorcycle or snow­mo­bile – com­pared with 80 or 90 de­grees for tra­di­tional ar­ti­fi­cial legs.

For safety and re­li­a­bil­ity, the bear­ings and bush­ings on the Moto Knee and Versa Foot must stay in place. Repet­i­tive, high im­pact con­di­tions and ther­mal cy­cling can cause press-fit com­po­nents to loosen and slip out of po­si­tion.

With no seats or shoul­ders to stop bush­ings from slid­ing in and out, Mike trusts a re­tain­ing com­pound to keep joint parts in place. Loc­tite 680 re­tain­ing com­pound and Loc­tite 7649 primer se­cure mul­ti­ple Am­pco 45 bush­ings and keep the stain­less steel ball bear­ings in place.

The spray-on primer cleans con­tact sur­faces and speeds anaer­o­bic cure. The bear­ing joints are then as­sem­bled us­ing Loc­tite 680 to pro­vide 100 per­cent con­tact within the joint, evenly dis­tribut­ing load and stress.

The ma­te­rial seals the bear­ing seats, pre­vents cor­ro­sion and ero­sion of the fit, locks the com­po­nents in place, and in­creases safety and dura­bil­ity. It didn’t take long for Mike to re­turn to com­pe­ti­tion.

Mike com­peted in the 2013 X Games in Los An­ge­les and This pros­thetic leg is de­signed for high im­pact sports, such as mo­tocross. A re­tain­ing com­pound keeps the leg’s bush­ings and bear­ings in place. Photo: Henkel Corp. won the gold in adap­tive mo­tocross.

Biodapt has sold 75 Moto Knees so far, mostly to ath­letes and wounded vet­er­ans.

“This whole project started be­cause I wanted to al­low my­self to do the things I wanted to do,” says Mike. “I’m help­ing peo­ple do things they haven’t done since they had two good legs.”­eren­quiry #141109

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