Athlete knows how to bond with artificial leg
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.”