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Living longer, living better

Can surgery help you stay in the game?

Demand for knee and hip replacement rises

A rthritic knee crimping your tennis game? Toss it out and get a new one.

Demand for joint replacement surgery, once confined largely to patients well past retirement age, has been growing rapidly among a class of people doctors have dubbed the “young actives’’ - those in the 45 to 64 age group who are determined to stay fit.

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Many still imagine the patient profile for artificial knees and hips, the most common types of joint replacements, as overweight elders seeking to ease joint pain while cooking or watching their grandchildren’s soccer games.

But the patients knocking on the doors of orthopedic surgeons today are just as likely to be athletic fiftysomethings who have exercised vigorously for years and are looking for joint prostheses that will help them resume cycling, skiing, or playing tennis.

“Young active people who are being slowed down in their lives are increasingly open to having these procedures,’’ suggested Dr. Jeffrey N. Katz, professor of epidemiology and environmental health at Harvard School of Public Health and director of the Orthopaedic and Arthritis Center for Outcomes Research at Brigham and Women’s Hospital.

Katz takes issue with the notion that baby boomers have cultivated a throwaway mentality, thinking they can discard worn joints like so many disposable razors. “It’s not so much a disposable generation,’’ he said, “as a generation of people who have things they want to accomplish and they don’t want their knees to get in the way.’’

As the number of joint prostheses has risen steadily during the past two decades - reaching 620,192 knees and 284,708 hips in 2009, according to the most recent data compiled by the US Agency for Healthcare Research and Quality - complaints about complications, botched operations, and the need for second surgeries known as “revisions’’ have been amplified.

In one high-profile 2010 case, medical device giant Johnson & Johnson recalled two kinds of hip replacement implants made by its DePuy Orthopaedics division because of higher-than-expected rates of early failure.

Still, even with the rise of obesity and longer lives, public health researchers say the rate of joint replacement failures requiring revisions is about 1 percent a year, mostly in the relatively younger patients who “outlive’’ the 10-to-20-year working life spans of their replacement joints. And as technique and technology have improved, the rates of infection, dislocations, and other complications have declined.

While there can be tension between the need to move forward with a procedure without delay and the importance of monitoring safety implications, more surgeons and patients alike have grown comfortable with joint replacements, said Elena Losina, codirector of the Brigham and Women’s research center. Its research is funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases.

In Massachusetts, knee and hip replacements are routinely performed at most Boston hospitals, ranging from Brigham and Women’s to New England Baptist, as well as in many suburban hospitals. Patients typically are hospitalized for three to four days.

Innovations in joint replacement, including the use of stem cells to replace damaged cartilage, are a fertile area of medical research. Procedures like autologous chondrocyte implantation, which repairs damage in articular cartilages without replacing the entire joint, already are being performed on young people with isolated cartilage defects from sports injuries.

For the foreseeable future, however, replacing aging knees and hips with prostheses is expected to be how the large majority of cases will be addressed.

Companies in Massachusetts, a hotbed for drugs and medical devices, have joined in the quest for better products and technology. Last month, for example, Burlington device maker ConforMIS Inc. raised $89 million to expand its commercialization of a next-generation customized knee replacement system.

With the influx of young actives, the number of US knee replacements has risen 144 percent for men and 157 percent for women from 1997 to 2009, said Anne Elixhauser, senior research scientist at the Agency for Healthcare Research and Quality.

The growth has been even faster for those under 65, more than tripling over the same period.

“The technology is better, we’re able to do it more safely,’’ Elixhauser said. “Maybe there are different expectations among baby boomers about the quality of life they want, and maybe more active people are wearing out their joints more quickly.’’

But she added a note of caution. “What we could expect to see in the future is the people in the 45-to-64-year-old category coming back to get revisions’’ - new knee replacements in second surgeries. With any luck, the second implants could be better.

Robert Weisman can be reached at weisman@globe.com.

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