Study examines usage, outcomes of knee replacement procedures among Medicare patients

September 25, 2012

There has been an increase in total knee arthroplasty (TKA; knee replacement) procedures over the past 20 years that has been driven by both an increase in the number of Medicare enrollees and increase in per capita utilization, according to a study in the September 26 issue of JAMA. There has also been a decrease in hospital length of stay for TKA, but increased hospital readmission rates and increased rates of infectious complications.

"Total knee arthroplasty is a common and safe procedure typically performed for relief of symptoms in patients with severe . Available data suggest that approximately 600,000 TKA procedures are performed annually in the United States at a cost of approximately $15,000 per procedure ($9 billion per year in aggregate)," according to background information in the article. Total knee arthroplasty is one of the most common and costly surgical procedures performed in the United States. "Despite the clinical and importance of TKA, there are few analyses evaluating recent trends over time in use of and outcomes associated with TKA."

Peter Cram, M.D., M.B.A., of the University of Iowa Carver College of Medicine, Iowa City, Iowa, and colleagues conducted a study to evaluate trends in primary and revision TKA volume, per capita utilization, and outcomes in the U.S. Medicare population for the time period between 1991 and 2010. The analysis included 3,271,851 patients (age 65 years or older) who underwent primary TKA and 318,563 who underwent revision TKA identified in Medicare Part A data files.

The researchers found that the number of primary TKA procedures increased from 93,230 in 1991 to 243,802 in 2010 (an increase of 161.5 percent), while per capita utilization increased 99.2% (from 31.2 procedures per 10,000 Medicare enrollees in 1991 to 62.1 procedures per10,000 in 2010). The number of revision TKA procedures increased from 9,650 in 1991 to 19,871 in 2010 (an increase of 105.9 percent), and per capita utilization increased 59.4 percent (from 3.2 procedures per 10,000 Medicare enrollees in 1991 to 5.1 procedures per 10,000 in 2010). Also during this time period, the prevalence of obesity among patients undergoing primary TKA increased from 4.0 percent to 11.5 percent. The average hospital length of stay (LOS) for primary TKA declined from 7.9 days in 1991-1994 to 3.5 days in 2007-2010, a relative decline of 55.7 percent. All-cause 30-day readmission rates increased from 4.2 percent in 1991-1994 to 5.0 percent in 2007-2010.

"Trends in discharge disposition after revision TKA demonstrated a similar pattern to that which was observed for primary TKA, a decline in discharges to home or inpatient rehabilitation and an increase in discharge to skilled care and outpatient rehabilitation," the authors write.

The researchers add that for revision TKA, a decrease in hospital LOS was accompanied by an increase in all-cause 30-day readmission from 6.1 percent to 8.9 percent and an increase in readmission for wound infection from 1.4 percent to 3.0 percent.

"These figures suggest that growth in primary and revision TKA volume is being driven by both an increase in the number of enrollees and an increase in per capita arthroplasty utilization," the authors write. "This growth is likely driven by a combination of factors including an expansion in the types of patients considered likely to benefit from TKA, an aging population, and an increasing prevalence of certain conditions that predispose patients to osteoarthritis, most notably obesity."

"The growth in TKA should prompt consideration of whether too many (or too few) of these procedures are being performed both in aggregate and among key patient subgroups defined by race, sex, or age."

James Slover, M.D., M.S., and Joseph D. Zuckerman, M.D., of the Hospital for Joint Diseases of New York University Langone Medical Center, New York, comment on the findings of this study in an accompanying editorial.

"The report by Cram et al characterizes some important epidemiologic aspects of primary and revision knee replacement that have occurred over the past 20 years, including the evolution of increased volume and changes in care patterns, complication, and readmission rates. In an effort to control costs and improve quality of care, the findings provide important information concerning patient demographics associated with primary and revision total knee replacements and complications. In the currently challenging and dynamic health care environment, critical evaluation and systematic data collection about total knee replacements will be needed to optimize outcomes and ensure access to these life-improving procedures."

Explore further: Study finds decrease in length of hospital stay after hip replacement, but increase in readmissions

More information:
JAMA. 2012;308[12]:1227-1236.
JAMA. 2012;308[12]:1266-1268.

Related Stories

Study finds decrease in length of hospital stay after hip replacement, but increase in readmissions

April 19, 2011
An analysis of data from Medicare beneficiaries who underwent hip replacement or subsequent follow-up corrective surgery between 1991 and 2008 indicates that the length of hospital stay after surgery declined during this ...

Aquatic therapy soon after total knee arthroplasty improves outcomes

December 21, 2011
Despite increased use of total hip arthroplasty (THA) and total knee arthroplasty (TKA), there is a notable lack of consensus about optimal postoperative treatment. Aquatic therapy has been shown to have a beneficial effect, ...

Study identifies patients at increased risk after bilateral knee replacement surgery

July 14, 2011
A new study by researchers at Hospital for Special Surgery has identified patients who are at a higher risk of morbidity and mortality when undergoing knee replacement surgery in both legs at the same time. The study found ...

Recommended for you

Smoking raises risk of aneurysm recurrence after endovascular treatment

August 17, 2017
In a new study, researchers report people who have experienced an aneurysm have another reason to quit smoking.

Study adds to evidence that most prescribed opioid pills go unused

August 2, 2017
In a review of half a dozen published studies in which patients self-reported use of opioids prescribed to them after surgery, researchers at Johns Hopkins report that a substantial majority of patients used only some or ...

Engineers harness the power of 3-D printing to help train surgeons, shorten surgery times

August 2, 2017
A team of engineers and pediatric orthopedic surgeons are using 3D printing to help train surgeons and shorten surgeries for the most common hip disorder found in children ages 9 to 16. In a recent study, researchers showed ...

World's first child hand transplant a 'success'

July 19, 2017
The first child in the world to undergo a double hand transplant is now able to write, feed and dress himself, doctors said Tuesday, declaring the ground-breaking operation a success after 18 months.

Knee surgery—have we been doing it wrong?

July 18, 2017
A team of University at Buffalo medical doctors have published a study that challenges a surgical practice used for decades during arthroscopic knee surgery.

New tools help surgeons find liver tumors, not nick blood vessels

July 17, 2017
The liver is a particularly squishy, slippery organ, prone to shifting both deadly tumors and life-preserving blood vessels by inches between the time they're discovered on a CT scan and when the patient is lying on an operating ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.