Scott Sulprizio was an avid hang glider until the day in 2001 that he injured his ankle while practicing the sport. A bone infection and many surgeries later, he was told that removing his foot altogether might be the best option. After the final surgery, Sulprizio did something that would eventually change the lives of other amputees: He designed a new kind of prosthetic foot—one that is going to be used by multiple athletes in this year’s Paralympic Games.
About six years ago, Sulprizio brought his invention to College Park Industries, a company that develops foot and ankle prosthetics. College Park had to do plenty of tweaking on Sulprizio’s design—the original model didn’t hold up to the company’s series of tests that put prosthetics through 2 million cycles, or the equivalent of about three to four years of walking. And making changes was no small feat; Sulprizio presented them with the physical prototype sans design documents.
"[The Soleus] provides a level of smooth transition [in walking] that’s very difficult for other companies to achieve because of the materials they’re using and their design," explains Mike Leydet, director of research at College Park Industries. Soleus is one of many prosthetics designed by the company.
College Park has the advantage of using iPecs (Intelligent Prosthetic Endo-Skeletal Component System), a sensor system that lets researchers collect telemetry from prosthetic users to inform product design and material changes. "The Achilles heel of competitors is the abrupt transitions between the springs that carry the load of the human body. It’s described by amputees as hitting a wall," says Ledet.
Of course, College Park does have plenty of worthy competitors, including Ossur, a company that makes the sprinting feet worn by Olympian Oscar Pistorius—an athlete dogged by accusations that his prosthetics give him an unfair advantage.
But in this year’s Paralympics, Team USA athlete Matt Brown will throw discus wearing the Soleus, and Japanese athlete Maya Nakanishi will compete in track and field with the prosthetic. "I am surprised by the durability of the springs. I weigh 270 pounds and put a considerable amount of stress on the foot. The Soleus has upheld its strength and flexion, and if anyone could put the Soleus to the test, it would be me," Brown explained in a letter to College Park.
As we have discussed, technology in the prosthetics industry is advancing rapidly. The PowerFoot, a robotic lower leg system, is billed as "the world’s first bionic lower leg system to replace the action of the foot," using a combination of processors, sensors, motors, and springs.
Leydet acknowledges that things are changing. "The technology is going towards micro-processor controlled knees, moving down the leg into the ankle area," he says. "We’re working on those advanced designs right now."