In December 2008, "Monster" Mike Schultz, then a 27-year-old rising star in the world of snocross racing, was in the middle of the pack at an International Series of Champions race in Michigan. A regular competitor at the X Games, he'd won a major race in Iceland and was pulling in respectable sponsorship dollars. "He was one of the best in the world," says Tim Reed, a senior director at the X Games. "He was in a pretty elite field." Hurtling a snowmobile down a hill, Schultz lost control of his sled on a rough section and was thrown off. The next thing he knew, he was lying on the ground in agony, his knee having buckled in the wrong direction. "My foot was on top of my chest," he recalls. "The EMT got there a minute or two later, and I just remember unzipping my pant leg and I could hear the gush of fluid. I'll never forget that sound."
Schultz had severed the nerve that controls his lower leg, and his doctors removed the limb. "I always thought the worst would happen – like paralysis," he says. "I never really thought about amputation." His wife, Sara, worried her husband would become seriously depressed, and considered covering up the snowmobiles and dirt bikes in their garage. But soon after the operation, Schultz told her, "It is what it is. We can't change it, so let's just move forward and make the most of it."
He wanted to get back on his snowmobile as quickly as possible but found that existing prostheses were too weak and immobile to handle the rigors of extreme sports. "I walked around the house with one," he says. "I was like, 'Nah, this isn't going to cut it.' " Instead, Schultz decided to build his own. He grew up in Minnesota and learned to weld and fix machinery working as a railroad car repairman. He began sketching out designs for a knee and consulting with friends about what he'd need to replicate that part of the body. "It was more mechanical than biological," he says. "I wanted to make it simple to manufacture." He came up with a prosthesis that looked like a giant toggle bolt, complete with a shock absorber that used compressed air for a spring. The design supported his weight in a squatting position, controlled the rate at which his artificial knee collapsed on impact, and allowed him to pop back up.
Using some of the $50,000 of insurance money he received for his injury, Schultz refined the concept, developing an extreme prosthesis he called the Moto Knee. At the 2009 X Games, which had launched adaptive competitions for action-sports athletes who have had amputations or spinal cord injuries, he won a silver medal in motocross while wearing an early model, then won gold at that winter's snowmobile event. "People get injured and they hear, 'You're never going to ski or walk again,' " says Beth Geno, executive director of the Extremity Games, another adaptive action-sports competition. "And you have guys like Mike coming up with these inventions who say, 'You know what? I am going to do this again.' "
With technical help from the suspension company Fox (one of his racing sponsors), Schultz launched his own company, Biodapt, in 2010. Since then, the Moto Knee has become an unlikely sensation: a piece of go-to gear for anyone who's lost a limb but still yearns to ski, snowboard, wakeboard, or skydive. His clientele includes a few motorcycle racers and a British jockey whose horse fell on him, but about half of his customers are veterans. (The government picks up the tab for the $6,200 Moto Knee and Biodapt's $2,300 Versa Foot, shown together, right.) Wayne Waldon, an Army captain who lost his right leg to a bomb blast in Iraq in 2007, uses the Moto Knee for snowboarding. "When you lose your physicality and freedom, you really lose yourself," Waldon says. "The Moto Knee took away a lot of the frustration that might have made me want to quit."
Schultz assembles, tests, and packages every Moto Knee at his home shop in St. Cloud, Minnesota. "I never thought it was a business," he says. "But here I am." Inside his workspace, steel cabinets filled with nuts and bolts line one wall, while the other is taken up with a long worktable covered with knees in progress. His wife helps with the paperwork, and he hopes to hire his first full-time employee soon. He's designing an artificial foot for downhill skiing and wants to create a leg that can be used for both sports and everyday walking. The number of military veterans alone who are leg amputees – more than 1,300 from the wars in Iraq and Afghanistan – represents a potentially lucrative niche market.
To accommodate his growing business, Schultz and his wife bought a larger house with enough land for a dirt-bike trail and their three horses. "Sometimes people say, 'Oh, you're doing better now than before the accident,' " Schultz says, walking his yard and gazing at the dirt track in the distance. "That irritates the hell out of me. Not a day goes by when I don't wish I had both legs. It gets harder every year to watch the pro class race because a lot of the guys I competed against are still competing at top level." Instead, Schultz has new goals: launching his own adaptive racing series or a reality show in which he'll take injured athletes and vets on adventures. "The Moto Knee shows people what's possible," he says. "It's about guys getting back in action in a sport they love."