The number of Medicare patients undergoing knee replacements in the USA rose by 161.5% over the last twenty years, researchers from the University of Iowa Carver College of Medicine reported in JAMA (Journal of the American Medical Association), 26th September issue.

The authors wrote that the total increase in knee replacement – total knee arthroplasty (TKA) numbers over the last two decades were driven by a rise in per capita utilization and Medicare enrollees.

TKA patients are being discharged from hospital earlier, but are being readmitted within thirty days of their operation more frequently. There are also higher rates of infectious complications today than twenty years ago.

Knee arthroplasty is a common and straightforward procedure, and is recommended for patients with severe knee arthritis. According to data gathered and analyzed by the authors, about 600,000 knee replacement procedures are carried out in the USA each year, at a cost of about $15,000 per procedure, an aggregate total annual cost of $9 billion annually.

Total knee arthroplasty is the most common surgical procedure in America, it is also one of the most expensive.

The authors wrote:

“Despite the clinical and economic policy 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., and team set out to determine what the trends were in primary and revision TKA volume, per capita utilization, and outcomes in the USA. Between 1991 and 2010, a total of 3,271,851 patients aged at least 65 years underwent primary TKA, while 318,563 underwent revision TKA, according to Medicare Part A archives.

Below are some highlighted data from the study:

In 1991, there were 93,230 primary TKA procedures

In 2010, there were 243,802 primary TKA procedures; an increase of 161.5% compared to 1991

Per capita utilization rose from 31.2 procedures per 10,000 Medicare enrollees in 1991, to 62.1 in 2010; an increase of 99.2%

In 1991, there were 9,650 revision TKA procedures, compared to 19,871 in 2010; a rise of 105.9%. Per capita utilization increased 59.4% among Medicare enrollees

The percentage of obese people undergoing primary TKA rose from 4% in 1991 to 11.5% in 2010

In 1991, the hospital length of stay for primary TKA dropped from 7.9 days in the 1991 to 1994 period, to 3.5 days in 2007-2010; a reduction of 55.7%

The percentage of patients who had to be readmitted to hospital within 30 days of their operation for any cause rose from 4.2% in 1991-1994 to 5% in 2007-2010

For revision TKA, the percentage of patients who had to be readmitted to hospital within thirty days rose from 6.1% to 8.9% over the 20-year period

The percentage of patients who had to be readmitted because of wound infections increased from 1.4% to 3%

The researchers wrote:

“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.”

Dr. Cram wrote: