Three years ago, Michael Rix was taking 250 milligrams of codeine a day and waking up in the middle of the night due to extreme pain in his left hip.
Rix, who was 42 at the time, had taken up marathons and was training around his hometown of Sussex, England. He stubbornly ran through the pain, logging between 100 and 120 miles a week, even as it became more acute. Then he woke up one morning and found himself incapable of reaching down to put on his socks.
He paid a visit to orthopedic surgeon Kerry Acton at the Royal Surrey County Hospital in Guildford, and was told that severe osteoarthritis in his left hip meant that he would need a total hip replacement.
The diagnosis didn't come as a shock - but he was surprised by what Acton said next.
"I was expecting him to say, after hip replacement, no more running nor more competition," Rix recalled to Seeker over the phone. "But instead he asked me, what would you like to do? I said, in an ideal world, I'd love to get back to sport - maybe not a marathon, but triathlons. He said, 'Yeah, we can do that.'"
Orthopedic surgeons are increasingly delivering promising news to patients who in previous years might not even have been considered candidates for joint replacement. Such surgeries were usually reserved for people over the age of 60, since the assumption was that the active lifestyles typical of younger people would inevitably break down the artificial joint and cause it to fail.
Today, several research fronts are revolutionizing knee and hip replacements to the point where the joints are practically becoming bionic, from 3-D printed implants to concept technologies that grow entire joints from stem cells.
The big trick behind these advances is recreating the durability of a natural joint in one that is manufactured, while also fooling the human body into believing that it's home-grown.
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Rix received an implant called the Furlong Evolution, which features a special ceramic coating that mimics a natural mineral present in human bone. The material triggers a biological bond to form between the implant and the patient's own bone, ensuring that the replacement lasts longer - hopefully for life.
Rix's implant bonded so well that three months after his surgery, he beat out 105 fellow competitors to win a local sprint triathlon. Now 45, he has competed for Team Great Britain in the last two European and World Duathlon Championships, winning a silver medal in his age group at the 2015 Worlds in Adelaide.
"I have no pain," said Rix, who had just returned home after a hilly, 10-mile run.
The complete lack of pain is a promising sign that Rix's hip replacement could last a lifetime. But if it should wear out, a future option might be a biological replacement grown from his own stem cells.
Farshid Guilak, a professor of orthopedic surgery at Washington University School of Medicine in St. Louis, has been working on methods to coax stem cells to develop into new joint cartilage to repair joints. The aim is to someday form entirely new knee and hip joints from stem cells.
Guilak and his team have developed a specially woven "scaffolding" that is designed to fit over a person's joint.
"We have a machine - it looks like a loom," he explained. "It weaves 600 fibers into a 1-millimeter layer."