Knee Replacement Doesn't Always Pay, Researchers Say

Knee replacement surgery isn't always a game changer, according to a new study that raises questions about the increasingly common procedure.

The patients who benefit most have severe osteoarthritis. But for people with milder symptoms, the expense might not be justified, researchers determined.

"This study suggests we should reconsider doing this procedure on people who have more mild pain, and less severe knee arthritis and loss of function," said Daniel Riddle. He's a professor of physical therapy and orthopaedic surgery at Virginia Commonwealth University.

Some in the medical community wonder if the procedure is overused, said Riddle, who wasn't involved in the study. For now, "the jury is still out," he added.

In 2010, total knee replacement was the most frequently performed inpatient procedure on U.S. adults aged 45 and older, according to the U.S. Centers for Disease Control and Prevention.

More than 640,000 knees are replaced with artificial joints each year in the United States, at a total cost of about $10.2 billion. The number of knee replacements doubled among women between 2000 and 2010, and there was an 86 percent increase among men, the researchers said.

Since 2000, eligibility for the procedure expanded to include patients with milder knee issues, which helps explain the explosive growth in surgeries, the study authors said.

Looking at these surgeries overall, the investigators found that knee replacement provides "minimal effects on quality of life." So, because patients with less severe symptoms don't gain a big benefit, the researchers questioned the procedure's cost-effectiveness.

The new study analyzed data on nearly 4,500 patients aged 45 to 79 who had knee replacements because of arthritis -- age-related degeneration -- or a high risk of it. The patients' average age was 61, and they had been tracked for nine years.

Among those with arthritis, the results showed improvement in pain, stiffness and physical functioning during daily activities, said study lead author Dr. Bart Ferket. He is an assistant professor of population health science and policy at the Icahn School of Medicine at Mount Sinai in New York City.

"It seemed that those with more severe symptoms especially contributed to these health benefits, and that the benefits were partly offset by less favorable effects found in those with less severe symptoms before their operations," Ferket said.

Because of this, "the effects on general well-being were less pronounced on average," he explained.

While it's expected that people in worse shape would benefit more, "there should be room for improvement in all, one might think," Ferket suggested.

Riddle said that the study has limitations. "We don't know how satisfied or unsatisfied these patients were with their outcome. That's a piece that this study doesn't examine."

After analyzing cost, the researchers reported that knee replacement in patients with less severe symptoms is "economically unjustifiable." The estimated cost of a typical knee replacement surgery, including rehab, was about $26,000 in 2013.

So, should less disabled patients not seek surgery? Riddle and Ferket suggested such decisions must be made individually.

"Patients need to have a good understanding of what to expect following a knee replacement surgery," Riddle advised. "We have a lot of data to give patients about where they're likely to end up."

For instance, prior research has found that up to one-third of patients experience chronic pain after knee replacement.

Anyone considering knee replacement should really think it through, Riddle said. "They should ask a lot of questions about what makes them a good candidate, what are the risks associated with this procedure, and what they should expect in terms of pain and function," he added.

Ferket said the findings aren't designed to guide individual patient decisions, especially since everyone has different goals.

However, he said, "doctors may share the results of our study indicating that outcomes could vary according to symptom levels before surgery."