Shark victim becomes trailblazer in bionic limbs

Seven years ago, a man named Craig Hutto barely survived being mauled by a shark. Since then he's been helping doctors create the most lifelike artificial limbs in the world.

Hutto's story begins with a bump in the water, reports CBS News correspondent Elaine Quijano.

"The bump was just kind of a soft punch, it felt like - and I just kind of jumped back and screamed, 'What was that?'" he explains to "The Early Show".

It was a bull shark.

"Then right in that instant, something takes me right under water and I didn't see anything."

The shark dragged 16-year-old Hutto underwater while he was on vacation fishing with his brother in Florida.

"Just like the movie, 'Jaws,' the shark just dragging me... When we were swimming back, the shark was still on my leg," remembers Hutto.

He tried to pry the shark off his leg with his hands.

"By now the shark had already bit my femoral artery so every heartbeat I was just pumping blood out, and that's basically all I saw the whole time swimming back. Just red."

Hutto had lost more than half of the blood in his body. After a harrowing ordeal he was rushed to the hospital by helicopter and into surgery.

"I said, 'Mom, please don't let them take my leg.' And right when I said that, mom, she just lost it," recalls Hutto.

His leg had been amputated from the thigh down.

"I was just devastated... I used to play basketball, football, since I could walk, basically."

At that point, Hutto was hoping to just walk again.

But within six weeks he was being fitted for a new prosthetic leg, and he was back at his high school in Tennessee.

"If you're missing an ankle and a knee, there are significantly more challenges," explains Dr. Michael Goldfarb, of Vanderbilt University.

The doctor Hutto was working with recommended him to Goldfarb. He was testing a new bionic leg made for active amputees like Hutto.

"Our leg is specifically designed for above-knee amputees, what we're doing is basically making a fully robotic leg," says the doctor.

Hutto's robotic leg goes further than regular prosthetics. It can help keep amputees steadier on their feet and help them climb slopes and stairs.

"Usually I have to think about every step, just because if I don't, that's when I get too relaxed and that's when I'll usually trip and fall," says Hutto.

So, three times a week he heads to Vanderbilt, tests the leg and makes recommendations.

Goldfarb tells CBS News the young man has "basically been the test pilot. (He) lets us know what is working, not working, what feels right, what doesn't feel right."

Now a junior in college, Hutto plans to get a masters degree in acute nursing.