Knee replacements soar among US older folks

Just like their counterparts, the babyboomers, older folks have seen a surge in knee replacement surgeries, driven partly by a desire to stay active and by joint-damaging obesity. A study finds more than 3 million Medicare patients who are 65 and older, got artificial knees from 1991 through 2010. Almost 10 percent of the operations were redos — replacing worn-out artificial joints.

The number of knee replacements each year on these older patients more than doubled during that time, rising to nearly 244,000 in 2010. Patients were in their mid-70s on average when they had surgery; that age edged up slightly during the study.

The aging population and rising number of Medicare enrollees contributed to the increase. But the per capita rate also increased, from about 3 surgeries per 10,000 enrollees in 1991 to 5 per 10,000 in 2010.

“There’s a huge percentage of older adults who are living longer and want to be active,” and knee replacement surgery is very effective, said lead author Dr. Peter Cram, an associate professor of internal medicine at the University of Iowa.


This study is posted in Wednesday’s Journal of the American Medical Association. But the pace of growth has slowed somewhat in recent years, possibly because increasing numbers of younger adults have also been getting artificial knees, which typically last 15 to 20 years. The troubled economy may also have slowed demand for an operation that costs about $15,000.

Each year nationwide, about 600,000 knee replacement surgeries are done, on adults of all ages, costing a total of $9 billion, the authors said. A journal editorial says measures are needed to control costs of these operations, noting that demand has been projected to rise to as many as almost 4 million knee operations annually by 2030.

Also, older obese patients getting their first operations accounted for almost 12 percent, up from 4 percent. The rate was about the same in those getting redos. Obesity takes a toll on joints and can contribute to arthritis, a leading reason for knee replacement surgery.

Then the average hospital stay dropped from almost 8 days to 3 1/2 days, but many patients were sent to rehab centers, mostly outpatient centers in the most recent years. Readmission rates after first and second operations increased in recent years for reasons including infections and surgery complications.

The study also said that shortening hospital stays doesn’t always achieve the goal of reducing costs, since readmissions increased — a trend seen with other types of surgeries and illnesses.

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