Medicare knee replacements surge 162% since 1991

A study finds hospital stays after the surgeries decreased, but readmission rates rose. Revision procedures have more than doubled in 20 years.

By Charles Fiegl amednews staff — Posted Oct. 8, 2012

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The popularity of total knee arthroplasty surgeries among Medicare patients has grown considerably as beneficiaries are living longer and seeking to increase their mobility, but the shift has led to fiscal concerns for the entitlement program.

The Sept. 26 issue of The Journal of the American Medical Association featured a study on the rapid growth of total knee replacements and revision surgeries. Its authors also noted a slight increase in readmissions among artificial knee recipients since 1991, as the average length of hospital stays after surgeries has been cut in half, to 3.5 days in the 2007-10 period.

Overall volume growth has been driven both by the increased number of Medicare enrollees and by increased per capita utilization, said Peter Cram, MD, a lead author of the study and director of the division of general internal medicine at the University of Iowa Carver College of Medicine in Iowa City. The number of total knee replacements increased 161.5% between 1991 and 2010, when 243,802 such surgeries were performed. Per capita utilization nearly doubled during that period, to 62.1 procedures per 10,000 Medicare beneficiaries from 31.2 surgeries per 10,000 enrollees.

“We are an aging society, and the number of beneficiaries is going up every year,” Dr. Cram said. “What we sought to do in our study is look at the long-term trends. We had different lessons sandwiched together in the same paper.”

For patients, knee replacements are relatively safe and have low rates for complications, mortalities and length of hospital stays. However, 30-day readmissions rates have risen to 5% in 2010 from 4.1% in 1991. Shorter hospital stays are causing the increase, a change that should have been expected by health policymakers, Dr. Cram said.

The volume of revision knee replacement surgeries has increased to 19,871 in 2010 from 9,650 in 1991. The per capita rate also has increased, to 5.1 revision procedures per 10,000 beneficiaries from 3.2 surgeries per 10,000 patients.

For Medicare officials, the doubling of per capita utilization of primary knee replacement surgeries is a cause for concern, Dr. Cram said. However, he said there is no conclusive evidence that points to overutilization of the procedure. Some patients elect not to have the surgery, which could point to underutilization, he added.

“It’s an effective therapy for an aging population who wants to be physically active. It allows you to ski mountains, hike the Appalachian Trail and run with your grandkids as you get older,” he said.

The data from the article show a success story, said John R. Tongue, MD, president of the American Academy of Orthopaedic Surgeons. Patients were apprehensive about the surgeries decades ago. Recovery required weeks in the hospital, as some patients would be afraid to get out of bed. But attitudes have reversed during the past 20 years, because knee replacements can relieve pain and increase mobility dramatically.

“It’s very positive,” Dr. Tongue said. “The only criticism I hear now is ‘I should have done it sooner.’ ”

More and more patients taking advantage of the surgeries will lead to higher Medicare program costs. The procedure itself costs about $15,000 to $30,000, Dr. Tongue said. The bundled Medicare payment for the procedure is spent on the device implants, facility fees, therapy providers and the surgeons. The surgeon probably will receive about $1,500 of the total, he said.

New Medicare payment models, such as the bundled payments used for knee replacements, aim to achieve lower costs while maintaining high quality to prevent patients from being readmitted.

The AAOS supports new Medicare payment models to support care coordination and empower patients to engage in programs prescribed by physicians, Dr. Tongue said. But he said the Medicare program needs to consider that seniors are living longer and doctors increasingly are performing surgeries on patients with one or more comorbidities.

“Some of my patients are obese, diabetics or have a history of coronary disease,” he said. “These patients in the past would have shunned this type of procedure, but now they seek it out.”

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Knee replacement patients now go home earlier but come back more

Roughly 3.3 million elective primary total knee arthroplasty surgeries were provided to Medicare patients between 1991 and 2010. Over time, bundled payments for the hospital procedures have prompted a dramatic drop in the length of patient stays in hospitals, but 30-day readmission rates after the surgeries also have increased.

Years Mean length of stay 30-day readmission rate
1991-94 7.9 days 4.2%
1995-98 4.9 days 4.1%
1999-2002 4.3 days 4.0%
2003-06 3.9 days 4.5%
2007-10 3.5 days 5.0%

Source: “Total Knee Arthroplasty Volume, Utilization and Outcomes Among Medicare Beneficiaries, 1991-2010,” The Journal of the American Medical Association Sept. 26 (link)

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