Hip resurfacing has been performed on 60,000 people over the last decade in Europe with no reported wear-related failures. Its apparent ability to restore hobbled athletes to their old selves is a big contrast to the clunkier total hip replacement, now annually done on 200,000 to 300,000 Americans, most over age 60.

A total hip replacement involves complete removal of damaged parts of the patient's hip joint and replacement with a prosthesis. The head of the femur is sawed off, replaced by a metal ball and arm held in place by a long spike hammered deep into the shaft of the femur. The surgeon then scoops out excess cartilage and bone from the socket part of the joint and fits a new socket. While pain-free mobility is restored, gait and skeletal stress is altered and vigorous activity, like running marathons, is not encouraged. In December 2006, California governor Arnold Schwarzenegger broke his artificial hip while skiing.

Resurfacing, on the other hand, preserves virtually all of the femur, precisely shaving a few centimeters off the surface before capping.

"It's a trickier, more difficult operation," says Dr. Rogerson, who, like most doctors, uses the Birmingham Hip Resurfacing (BHR) technique and device pioneered and patented a decade ago by Dr. Derek McMinn in Birmingham, England. (BHR is now owned by Memphis-based Smith and Nephew. A similar device is made by Stryker of Kalamazoo, Michigan.)

The procedure takes 90 minutes or so, twice that of a hip replacement. The socket cupping is similar to that of a total hip replacement, although it uses more durable cobalt-chromium instead of plastic. The resurfaced femur head is much larger than a total hip's smaller-diameter total-hip hardware and therefore less prone to dislocating.

Of course, the higher quality of life comes at a price - $30,000 or more in the United States for a hip resurfacing, 20 percent or more over a total hip replacement. Overseas is cheaper: £11,995 in England (see www.mcminncentre.co.uk) and half that in India by McMinn-trained doctors.

Until two years ago, Americans had to go overseas for the operation. Resurfacing, invented in the 1970s, got a bad rap when the plastic parts of the early devices wore out quickly. The lingering apprehension about quality delayed U.S. approval, even after durable all-metal parts arrived.

The big question: How fast can you be up and running after the operation? According to the McMinn Centre Web site, "One year after operation. At around 11 months, you may start jogging on a treadmill with good quality running shoes or trainers. Do this for a couple of months before you start running outdoors or participating in high-impact sporting activities like squash, cricket, football, etc."

To many, waiting a whole year to run after hip resurfacing seems too conservative. To Cory Foulk, the poster boy for this operation, even a month was too much.

Foulk, a 49-year-old Hawaii architect and lawyer who writes environmental impact statements for luxury resorts, earned his hip resurfacing with a mega-mile resume that's off the charts. He has finished the UltraMan (a triple Ironman distance) 15 times. He's done 50 ultra-marathons, 50-plus marathons, and has 41 Ironman finishes. He ran 40 miles in a typical week and totaled 66,560 lifetime miles.

"I never considered not doing this forever," says Foulk. But nine years ago, he broke his hip in a bike accident. A few years later, the pain began. Like Landis, he had avascular necrosis; part of his hip was dying.

"At the 2001 Ironman South Africa, I had a great bike, but I couldn't run a step," he says.

His hip was a mess. X-rays showed pieces of bone all over the place.

"If you were older, we'd do a hip replacement this week," the doctors said. "But you're too young and active. Wait five years for the technology to get better. Until then, take pain drugs."

So Foulk did - and kept doing Ultramans. He switched from running to deep-water running. He tried inversion therapy, crystal therapy, acupuncture, took glucosamine supplements and put lifts in his shoes to even out leg length. But his hip got worse.

Finally, Foulk heard about hip resurfacing from Drew Dixon, a 50-something triathlete who had the operation done in Belgium and finished an Ironman three years later. Quickly, he settled on a different McMinn-trained doctor in India who offered an $11,000 package deal that included a luxury hospital suite and a beachfront recuperation villa.

The pampering worked wonders. Six days after the operation, to the horror of his doctor, Foulk ran a 5K on a treadmill. He ran a marathon on his three-month anniversary, did Ironman Germany in month seven and a 24-hour run soon after.

Since his operation on December 21, 2005, Foulk has done five Ironmans and three Ultramans, finishing 11th out of 35 at the world championships.

"All with a fake hip!" he chuckles. "I am bionic!"

Being one of the first hard-core athletes in the United States to have the operation, Foulk wasn't sure what to expect. At his last race before flying to India, he said goodbye to all the race directors, competitors and even the aid-station volunteers that he had seen over the years, thinking he might never see them again.

"But now I have a barcode and a warranty," he says. "The doctors are worried that I'm pushing it, but the engineers tell me that it won't ever wear out. "

Whole again, Foulk started spreading the word. By way of Competitor Magazine Publisher Bob Babbitt, he was connected to Tinley, Benincasa, Kobat and even Landis, who switched to a hip resurfacing instead of a planned total hip replacement.

Foulk turns a half-century this year.

"The 50s is the gravy," he says. "You're still fit, you've made the money, and you've got it all figured out. I got a second chance, and I'm not going to waste it."

Years and years of megamiles pound, tear and pulverize the hidden structures that make us move with a fluid grace we only think about when it's gone.

For years, baby boomers thought they were hammering the road to endless health, only to find themselves decades later becoming the first overtrained generation and staring at an X-ray of a gimpy, arthritic joint better suited to a battered ex-NFL lineman.

"The crazy endurance stuff didn't happen until our generation," says Benincasa. "I always laughed at people who said, ‘Wait ‘til you're 40 and all your joints are worn out."

The laughter stopped for a while. But it's back now every time Benincasa goes for a run - or sets off the metal detector at the airport.

"We knew we were lab rats, erring on the side of excessive miles," says Tinley, who guesses he's run, biked and swam "to the moon and halfway back."

"I always knew I was doing too much," he says. "I knew I could get by on two-thirds of the mileage I was doing."

The warning signs were there. In 1997, when a lab test showed that Tinley wasn't producing cortisol, a hormone the body produces in response to stress, a doctor told him he needed to take two years off. So he took off a month.

Although he's already surfing 11 weeks after the operation - against doctor's orders - Tinley is towing the line on land.

"I'm taking it slow on the running," he says. "Not until summer. And then, no 40-mile weeks."

When he turns 50 in October, a nice birthday present awaits. "I'll have a life back," he says.

A lot of go-for-broke baby boomers will clamor for the same gift.

"[The doctors] will have an endless supply of resurfacing patients," says Benincasa. "Because we don't want to stop. We're having too much fun."

Endurance cyclist and runner Roy M. Wallack is the co-author of "Bike for Life: How to Ride to 100." See his television interview on super-fit aging tips at www.bikeforlifebook.com.

For more information on hip resurfacing, go to www.surfacehippy.info.