Question of the Month

ASME Strategic Roadmap

White Paper Library



By Jean Thilmany

Prosthetic limbs historically have been seen as poor substitutes at best for natural appendages. But the state of the art has far surpassed the hooks and peg legs of old. Indeed, ethicists have recently debated whether an amputee might have an actual advantage in an athletic event.

The image of prosthetics has been undergoing such a radical transformation that the cable channel Canadian Discovery Science promoted a program in March with this pitch:

“Stuntman and amputee Casey Pieretti, and inventor Bill Spracher, design, build and test one-of-a-kind, extreme limbs that make their amputee clients better than new, better than you.”

The one-hour special, Bionic Builders, purported to depict the deliberate blurring of man and machine. Its very premise spotlights some of the questions raised by researchers—and by the public—as scientists work toward ever more intuitive and more powerful bionic limbs and other body parts.

One view is typified by New York Times contributor Jack Hitt, who tackled the issue in his November 2009 article, “Are High-Tech Prostheses Fair?” In Hitt’s view, athletic events like foot races ought to be open to disabled athletes with lower-leg amputations who use high-tech prosthetics. Yes, today’s prosthetics may have an advantage in contests against ordinary competitors, Hitt wrote, but “the fact is that this piece of equipment isn’t supernatural and doesn’t bestow any occult powers on those who possess it.”

Input/Output - Pieretti swims at superhuman speeds and leaps crazy heights with prosthetic limbs

Hollywood stuntman Casey Pieretti swims at superhuman speeds and leaps crazy heights with prosthetic limbs designed by engineer Bill Spracher.

Input/Output - Hollywood stuntman Casey Pieretti

The bionic versus non-bionic competitor question had its real-world case study in the attempts of Oscar Pistorius to run at the 2008 Olympics in Beijing. Pistorius has a double amputation and wears J-shaped blade extensions on his legs. To disqualify Pistorius, the International Association of Athletic Federations quickly amended its rules to prohibit the use of any technical device that incorporates springs, wheels, or any other element that provides the user with an advantage over another athlete not using such a device.

In support of this ruling, studies commissioned by the IAAF showed that Pistorius would have, in fact, had an advantage against other sprinters. Later, scientists claimed they found the IAAF-funded study flawed.

The debate will doubtless continue into the future, as engineers push the boundaries of prosthetic limb design and use. For a glimpse of that future, meet Casey Pieretti, who lost his right leg when he was 19 years old. He went on to participate in triathlons held for athletes with and without prosthetics.

Along the way, he became a Hollywood stuntman. Pieretti was a stunt double in the 1997 film Starship Troopers, playing a character who had his leg gruesomely torn off.

Pieretti’s career was aided through the years by Bill Spracher, owner of Spracher Engineering Inc. of Santa Barbara, Calif. In addition to making polyurethane parts for demanding industrial applications, the company also designs special legs for Pieretti’s stunt work.

The pair spoke earlier this year at SolidWorks World, the conference for users of the CAD technology. There, they outlined how they work together.

Should Pieretti find stunt work on a movie in which he needs to explode or to jump out of a dangerous situation, he talks to Spracher. Together they will come up with a few designs. From there, Spracher creates a leg that can explode or can catapult him off the ground.

At one point Pieretti wanted to scuba dive and requested a special prosthetic flipper. Spracher came up with a leg that could be used for both walking and swimming. Pieretti then tried the leg and proposed enhancements, resulting in a prosthetic propeller that enables him to move through water faster than any non-amputee could hope to.

Pieretti told conference goers that he’s no longer disabled; he’s super-enabled.  He and Spracher have now have formed a specialized prosthetics company, Amp’d Gear, through which they sell some of the specially designed prosthetics.

The Bionic Builders show followed the team as they tried to turn a former U.S. Navy diver into a human torpedo and give a one-handed martial arts instructor his very own bionic punching arm.

As the blurb for the show stated, the Bionic Builders will test, build, and design until disability is a word of the past. What that show doesn’t address is the debate that will be inevitably raised by the builders’ engineering successes: What exactly constitutes a human disability in this brave new world of prosthetic design?  


ABOUT US | BACK ARTICLES | ASME.ORG | ADVERTISE | CONTACT US | Terms of Use | Privacy Statement | Copyright © 1996-2011 ASME International. All Rights Reserved.