Artificial Joints: Knee and Hip Replacement Rates Rising


Thinking about getting a new knee or a new hip next year? You’re not alone. For baby boomers, it seems that joint replacements are as prevalent as iPods are for teenagers.

About 500,000 knee replacements and more than 175,000 are performed annually, and those numbers are on the rise. In fact, hip replacements are expected to increase 174% in the next 20 years, and knee replacements will rise even more — 673%, according to a study presented at the American Academy of Orthopaedic Surgeons’ 2006 annual meeting.

What’s behind the growing demand for new joints?

Blame it on the lifestyle of the baby boom generation, says Mathias Bostrom, MD, an orthopedic surgeon at New York’s Hospital for Special Surgery, where total knee replacements were pioneered.

“They’re not willing to be sedentary or change their lifestyle,” Bostrom tells WebMD. “Their joints are beat up and they’re living longer, and they want joints that let them do the things they’re used to doing.”

This also means that younger people, in their 50s and even 40s, are demanding joint replacements, increasing the market for the surgery. It’s a trend that Bostrom sees mirrored at his hospital, as well as throughout the U.S. and in Europe.

Are joint replacements inevitable as we live longer?

“A hundred years ago, maybe we did more manual labor and worked our joints more, but we also didn’t live nearly as long,” Bostrom says. As our life expectancies increase, we’re putting more demands on our joints — and perhaps, hitting their sell-by dates. “Maybe our joints weren’t designed to last as long as we’re living these days.”

A couple of decades ago, the majority of people needing joint replacement surgery had rheumatoid arthritis, a disease for which treatment has markedly improved. Now, osteoarthritis — caused largely by trauma and wear and tear on the body — is the leading reason for joint replacements.

Another reason behind the growing demand: joint replacements are getting better. “It’s still major surgery and not as good as a native joint,” says Bostrom. “But people do very well with joint replacements, and they last a long time, so many people are less anxious about getting them because they’re more comfortable with the longevity of the joints.”

Why is the demand for knee replacements so much higher than for hips?

We’re harder on our knees, Bostrom says, while at the same time doctors have learned to take better care of hips. “A lot of the pathology we used to see in hips was due to not recognizing early hip disease in infancy,” he explains. “Now that we’ve gotten better at screening for hip dysplasia, those indications for hip replacement have declined markedly.

“Meanwhile,” he notes, “we’re beating up our knees more. There are a whole group of people who’ve had meniscal tears and ligament tears due to athletic activities. Even if that damage has been treated, it may still cause a problem long-term.”

Will we face a shortage of artificial joints in the future?

Unfortunately, the demand for joint replacement surgery may soon outpace the availability. There are plenty of artificial joints — no shortage there. But there may not be enough qualified surgeons to implant them. Fewer medical students and residents are going into orthopedic surgery, says Bostrom, and joint replacement is not that popular a subspecialty within the field. “Many people would rather go into spine and sports medicine, which are much more lucrative,” he says. “There’s clearly going to be a lack of qualified people doing joint replacements, there’s no doubt about that.”

A look back at the projected growth in joint replacement surgery backs him up. Another study presented at the 2006 American Academy of Orthopaedic Surgeons’ meeting compared the number of anticipated surgeries with the number of surgeons expected to be available in 2010, 2020, and 2030. In two years, it found, the mean annual caseload per surgeon will be about 52 surgeries annually. By 2030, the annual caseload should triple to 167.

But career paths often veer to meet a huge demand, and it’s possible interest in orthopaedic surgery will increase as demand grows. If not? Expect to plan your joint replacement a few months — or even a year — in advance.