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Study: 4.5 Million Americans Had Knee Replacement Surgery

Knee brace (


Researchers at Brigham and Women’s Hospital in Boston calculate that more than 4.5 million Americans have had a total knee replacement (TKR), becoming one of the most common conditions affecting people in the U.S. age 50 and over. The team led by Elena Losina of the hospital’s Orthopedic and Arthritis Center for Outcomes Research, presents its findings today at a meeting of the American Academy of Orthopaedic Surgeons.

The team used the Osteoarthritis Policy (OAPol) Model, a computer simulation program developed by Losina to evaluate the epidemiologic factors that affect knee osteoarthritis. The researchers also factored in U.S. census data, as well as data from the National Health Interview Survey and two national longitudinal studies of persons with knee osteoarthritis — Multicenter Osteoarthritis Study and Osteoarthritis Initiative.

The results show osteoarthritis, the wearing away of cartilage that covers the ends of bones in the joints, to be the main reason for TKRs. The 4.5 million Americans currently living with at least one TKR represents 4.7 percent of the population age 50 years or older. This rate, says the team, is higher than the percentage of Americans with congestive heart failure and rheumatoid arthritis.

The findings show more women (5.3%) than men (4.1%) having TKR surgeries. The prevalence of TKR also increases with age, from about two percent of those age 50 to 59, to about 10 percent of those age 80 or higher.

The authors note that the number of TKRs performed in the U.S. has doubled in the last decade, exceeding 600,000 in 2009. The growth in TKR use has been greatest among younger people, with the average age at which patients receive TKR decreasing over time. “We now have a lot of people living with TKR,” says Losina, “which may lead to substantial increases in the likelihood of revisions and complications, especially in younger patients.”

Read more: Health Care Systems to Share Practices on Quality, Costs

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