The vast majority of patients with knee osteoarthritis in the United States who are considered appropriate for total knee replacement do not receive the surgery in a timely manner, whereas many who are not appropriate candidates have the knee replacement anyhow — prematurely, with both scenarios carrying important risks, new research shows.

"Our study suggests that there is a potentially large number of patients with knee osteoarthritis in the US who could benefit from total knee replacement but do not undergo the procedure," the authors report.

The study, published this week in the Journal of Bone and Joint Surgery, is believed to be the first of its kind to prospectively assess the timeliness of knee replacement among a large number of patients with knee osteoarthritis.

"With nearly 1,000,000 total knee replacements being performed in the US each year, the present study provides important impetus for future efforts directed at measuring and improving timely utilization of total knee replacement," the authors say.

The research included patients who had knee osteoarthritis or were at risk of the condition from two large prospective cohort studies — the Osteoarthritis Initiative (OAI), conducted from February 2004 to May 2006 at four clinical sites, and the Multicenter Osteoarthritis (MOST) study, evaluating patients from April 2003 to April 2005 at two sites.

Of a total of 8002 knee osteoarthritis cases identified in the two studies, 3417 knees met inclusion criteria for the analysis.

After a follow-up of up to 8 years, only 9% of those considered to be potentially appropriate for total knee replacement received total knee replacement surgery within a "timely" manner, defined as within 2 years of becoming potentially appropriate for the surgery.

Meanwhile, 90.7% of those considered "potentially appropriate" for the surgery did not have the replacement in a "timely" manner.

In addition, among the 1114 total knee replacements that were performed, 26.4% were considered to be "likely inappropriate" and therefore premature.

Picture of a female patient with degenerative knee joint. Photo

The criteria for the appropriate timing of knee replacement surgery was based on evidence-based recommendations that consider factors including age, symptomatology, radiographic knee osteoarthritis severity, number of knee compartments involved, and knee stability.

Key factors associated with an increased risk of not having a knee replacement when appropriate included being African American (odds ratio [OR], 2.81), and the likelihood of having premature total knee replacement surgery was lower among participants with a body mass index above 25 kg/m2 (OR, 0.33) and those with depression (OR, 0.37).

Among the knees considered potentially appropriate but not replaced, nearly half (42.5%) of patients had severe symptoms, defined as combined Western Ontario and McMaster Universities [WOMAC] Pain and Physical Function scores of 34 or above.

In addition to the sustained pain, the delay in knee replacement when the surgery is considered appropriate can lead to a cascade of undesired events, lead investigator Hassan Ghomrawi, PhD, MPH, said in a news release.

"When people wait too long, two things happen," said Ghomrawi, who is an associate professor of surgery at Northwestern University Feinberg School of Medicine in Chicago, Illinois.

"The osteoarthritis causes deterioration of their function. Some of them wouldn't be able to straighten out their legs, affecting their walking and mobility," he said. "When you can't get exercise, you can start to develop other health problems such as cardiovascular problems. You may also become depressed. The overall impact can be huge."

Secondly, the surgery itself may provide less benefit if delayed.

"You don't get as much function back when you wait too long; your mobility is still reduced vs somebody who had it in a timely fashion," Ghomrawi said.

Undergoing total knee replacement too early, in addition to likely providing little to no benefit, can mean exposing patients to the numerous risks that are associated with a major surgery.

Since total knee replacement is elective, a host of demographic, socioeconomic, and sociocultural factors can all come into play in determining whether, and when, a patient has the surgery, even in the context of pain, the authors write.

"While it is reasonable to assume that a subset of such patients have sensible reasons for not undergoing total knee replacement (for example, medical contraindications or the need to delay surgery because of the responsibility of caring for others, eg, a spouse or parent), the rest actually may benefit from surgery."

Evidence points to several specific reasons for the higher rates of delays among African Americans, including research that indicates a greater likelihood of having lower expectations of surgery, the authors add.

"In addition, physician networks in communities with higher proportions of black residents are more likely to be smaller and more insular, which may result in lower utilization of and poorer access to total knee replacement," they say.

"Understanding the reasons and barriers resulting in delay in those subpopulations is important, as the superiority of total knee replacement over nonoperative management has been demonstrated."

The study was funded by grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health. The authors have disclosed no relevant financial relationships.

Journal of Bone and Joint Surgery. Published January 13, 2020. Abstract



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