Local residential contractor Jack Burton has always enjoyed an active life, especially biking, but that and other daily activities, climbing ladders and stairs, became miserable for him more than a year ago.

Knees by the numbers

4.5 millionNumber of Americans who have an artificial knee.500,000 Americans who have two artificial knees.One in 10 Number of Americans 80 and older who have artificial knees.One in 20 Number of Americans 50 and older who have an artificial knee.676,000The total number of knee replacement surgeries that took place in 2009.Sources: Centers for Disease Control and Prevention; American Academy of Orthopaedic Surgeons

Burton’s right knee was shot, likely the result of a joint disorder, osteochondritis deformans juvenilis, he had at age 15, and decades of using his right leg to overcompensate for a severe left ankle injury that happened as a teen.

“In July 2011, I was biking with so much pain that I had to give it up. I devoted all my time to swimming,” says Burton, a former collegiate swimmer and one-time Ironman triathlon finisher. “But it was more than that. The pain got to the point where I couldn’t do my job effectively.”

After trying physical rehabilitation, massage and acupuncture, Burton went to the South Carolina Sports Medicine & Orthopaedic Center in North Charleston to get his knee checked out. The verdict was clear. He needed a total knee replacement, or “artificial knee.”

Burton had the knee surgery in April. Five weeks later, he was back on a bike easing his way into one of his favorite activities. Now, the 56-year-old is back up to speed.

“It (the artificial knee) has given me back so much of what I enjoy,” says Burton.

The wave ahead

Modern knee replacements date back to the 1970s. The cost for knee replacements runs about $15,000, and Medicare and most insurance companies cover justified cases.

The numbers of people who have gotten knees — and are projected to get them in the future — are staggering.

According to the federal Agency for Healthcare Research and Quality, knee replacements tripled in people ages 45-64 between 1997 and 2009. In the latter year, the Centers for Disease Control and Prevention says 676,000 people, or 213 for every 100,000 Americans, had knee replacement surgery.

A new study, published this fall in the Journal of the American Medical Association, noted that more than 3 million Medicare patients ages 65 or older received artificial knees from 1991 to 2010 and that the rate of replacements jumped from 31 per 10,000 in 1991 to 62 per 10,000 in 2010.

Of the total number of knee replacements in 2010, 244,000 seniors received the surgery, which also led to increased rates of postsurgical infections and complications.

“There’s a huge percentage of older adults who are living longer and want to be active,” and knee-replacement surgery is very effective, lead author Dr. Peter Cram of the University of Iowa told The Associated Press.

Obesity, which puts pressure on joints and can lead to arthritis, also played a role: The rate of obese older patients getting their first knee replacement tripled from 4 percent to 12 percent in the past two decades, the study found.

Changing dynamics

Dr. Seth Kupferman, the surgeon who performed Burton’s surgery, has been performing knee replacements for 23 years. He has witnessed a change in patient profiles for two very different reasons: obesity in younger people and older people wanting to be active.

“We’re more commonly seeing people in their 30s and 40s that have significant arthritis in their knee (due to being obese),” says Kupferman.

He adds that obese patients who receive artificial knees and remain obese are more prone to have not only complications with infections and proper knee rehabilitation but also accelerated wear on the replacement.

Meanwhile, Kupferman says baby boomers, a generation that started hitting 65 six years ago, who are active have expectations to remain active.

Allowing them to do so, in turn, pays dividends on their overall health and longevity.

At the same time, Kupferman says the process of replacing knees is improving on all fronts, including the technology of the artificial knee, surgical techniques and tools, physical therapy and post-surgical pain management.

The latter can be a stumbling block to recovery, as it affects critical post-surgical physical therapy and rehabilitation, says Kupferman.

Advances for pain management have gone from using narcotics to using pain blocks, notably by using a femoral catheter in the thigh to do blocks of the nerve running down the back of the leg, says Kupferman.

“A total knee is a pretty big operation. You’re cutting muscle, you’re cutting bone and then you’re asking the patient to bend their knee. You can blunt that pain with blocks, which results in less nausea and better cooperation in therapy,” says Kupferman. “They are obviously a lot happier.”

Good track record

Despite the improvements in knee replacements, the earlier versions aren’t doing so bad either.

“I see people in my office that we did 20 years ago who are doing absolutely fine,” says Kupferman.

Bobby James, a patient of Kupferman’s colleague, Dr. James Dalton, had a total knee replacement in 2005 when he was 58.

The retired air-conditioning foreman who lives in Goose Creek chalked up his bad knees to “wear-and-tear” and the fact that his father, a tobacco farmer, also had bad knees. His only relief was rubbing pain-relieving liniment on his legs.

Like Burton, James says he doesn’t really have to think about his knees anymore.

“I’m doing fine. I haven’t had any more problems,” he says.