No one should be surprised by last night's great fourth-quarter report from wheeled-footwear pioneer Heelys (NASDAQ:HLYS). I had predicted "a blowout fourth quarter" two months ago, and no one wrote me back to say that I was crazy. Even those who feel that the rolling shoes will be a passing fad knew better than to avoid a holiday season that seemed to belong to Heelys.

The company delivered as expected. Net sales soared 377% to hit $71.1 million. Earnings per diluted share leapt 633% to $0.44 a share. Analysts seemed to be the only ones caught off-guard, stalling out at the $0.28 per share mark.

Operating margins were on fire, rising to 25% for the quarter after a 15% performance a year earlier. The gross margins didn't deliver the knockout blow here -- they held relatively steady. Instead, the company's ability to keep overhead costs growing more slowly than its torrid top-line gains made the margin-munching possible.

So it's got the be the shoes, right?
It's funny. Two of the best-performing IPOs last year were shoemakers Heelys and Crocs (NASDAQ:CROX). Then again, they're not just making cookie-cutter footwear. Each company has lived up to its hype as an industry disruptor by bringing something new to the table. The hole-laden Crocs may be ugly, and the rolling Heelys may be dangerous, but consumers have taken to the funky footwear. Find a way to get some wheels to pop out of those cozy Crocs sandals, and fuhgeddaboutit!

Fashion can be fickle, of course. Just ask True Religion (NASDAQ:TRLG) shareholders how they felt last year, when sales growth of the pricey designer denim slowed. However, you also have success stories, too. Skechers (NYSE:SKX) and LaCrosse Footwear (NASDAQ:BOOT) have seen their shares grow fivefold over the past four years. Nike (NYSE:NKE) has never had a problem getting shoppers to pay a premium for its athletic footwear. Under Armour (NYSE:UA) has been selling its sweat-spurning apparel successfully for a couple of years now.

The long road from fad to foundation
We don't know whether Heelys will pass the test of time. Maybe the company won't be able to develop into a diversified shoe-cobbling empire. Thankfully, a lot of that uncertainty is already baked into the stock. How else would you explain a stock that grew its bottom line by more than 600%, trading at a relatively modest 31 times trailing earnings?

Heelys does not provide guidance. Its only futuristic nudge is a forecast for annualized 20% to 25% growth over the long haul. Don't bank on that, though. You may never live through a year of 20% to 25% growth at Heelys. As a one-product company -- and a hot product at that -- earnings are likely to rise at a much faster clip than that in the near term, or crumble disastrously if and when the product's popularity begins to wane.

There are too many domestic retail channels to fill, and too many international markets to populate, to get in Heelys' way now. Too many short-sellers got burned by betting against a fad stock too early in its growth trajectory.

However, this will probably never be a "buy and hold" stock, either. Investors need to be watchful, and pick it apart after every passing quarterly report. It may be a lot of work for some investors, but it's been worth it so far. The stock is trading 70% higher than its IPO price just three months ago.

Like Heelys shoes, you risk a tumble in pursuit of a fun ride. That may be worthwhile for aggressive investors, but if so, make sure you wear some protective gear.

Roll through the company's brief publicly traded life:

Heelys is not a recommendation in any of the newsletters. But Rick loves to spot early-adopter trends, and he's singled out plenty of them for Rule Breakers readers. Under Armour is one of the active picks in that newsletter. What makes them so special? A free 30-day trial subscription will help clue you in.

Longtime Fool contributor Rick Munarriz has two young sons, but only one of them likes to wear his pair of Heelys on certain outings. He does not own shares in any of the stocks in this story. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.