The Total Knee Replacement Crowd: Bigger, Younger, and More Diverse

“Total knee replacement? And when did you have yours?” Forget the Jane Austen- or Edith Wharton-style banter. There’s a whole new topic for dinner conversations, and it’s total knee replacement (also known as total knee arthroplasty). Last Monday, researchers from the Mayo clinic released results of a study that showed that, at least in the United States, more people, younger people, and people from more diverse backgrounds are having total knee replacements.

The researchers looked at data from the Centers for Disease Control and Prevention’s National Hospital Discharge Survey ( and compared data for people having total knee replacements during two time periods: 1990-1994 and 2002-2006. About 800,000 procedures were performed in 1990-1994, and 2.1 million in 2002-2006. To put that in perspective: More people had total knee replacements between 2002-2006 than live in the entire state of New Mexico.

While the numbers went up, the average age went down by two years (from 70 to 68 years of age). In addition, the percentage of minorities increased by 1.4 percent (from 8 percent to 9.4 percent). The study also found that Medicare is paying less for total knee replacements, and the length of hospital stays decreased. Medicare only paid 61 percent of the cost of the procedure during 2002-2006, compared to 72 percent during 1990-1994. Hospital stays went from 8.4 days to 3.9 days, while more people went to short- or long-term care facilities after surgery.

The researchers don’t take a stab at explaining the reasons for the more than twofold increase in total knee replacement, but they do point out implications for the future. “This information will be useful for planning for the future,” says Michele D’Apuzzo, M.D., the Mayo Clinic orthopedic surgery resident who led the study. “Total knee replacements aren’t going away any time soon. We’re going to be seeing younger patients undergoing this procedure. Younger patients have a higher chance of getting revisions, and physicians and medical facilities need to prepare for that.”

As huge as those implications are for our health system, and for the millions of people now walking around on replacement knees, the reasons for the increase — in number, diversity, and age range — need to be carefully examined. Is it simply that the need for total knee replacement is being recognized more frequently? Is there a link between lack of access to health care (more frequent among minorities in the United States) and arthritic degeneration? Has the procedure become so commonplace that it’s being overused? Is it linked to the dramatic rise in obesity in the United States?

Total knee replacement is not something to be taken lightly — while 90 percent of people experience dramatic reduction in pain, it’s not a panacea. While complications are rare, they can be serious — ranging from blood clots in leg veins (which can potentially travel to the lungs, with deadly consequences) to infection to loosening of the artificial joint. For active people, total knee replacement may require dramatic shifts in lifestyle — giving up high-impact sports, increased susceptibility to fractures, and being prepared to set off airport screening alarms, for starters.

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