News Release 

Race and poverty not risk factors for total knee replacement revision or failure

Results of a new study conducted at a high-volume orthopedic hospital

Hospital for Special Surgery

Previous studies have established that black patients have a higher risk for knee replacement revision. Black patients also report significantly more pain and worse joint function two years after surgery compared to white patients. Some years ago, a team of investigators at Hospital for Special Surgery analyzed HSS patient data and found an interaction between race and poverty that impacted patient reported pain and function two years after surgery. They discovered that black patients from wealthy neighborhoods fared as well as white patients, but black patients from poor areas experienced fared significantly worse than white patients.

Now, in a new study published in Arthritis Care & Research that looked at the risk of total knee replacement revision or failure, HSS investigators found very a different result. "There was a trend toward race being a risk factor, but it was not statistically significant, and poverty had no impact: There wasn't even a trend," said lead study author Anne R. Bass, MD, an attending physician and program director of the Rheumatology Fellowship Program at Hospital for Special Surgery, and a professor of clinical medicine at Weill Cornell Medicine. "We were definitely surprised by our results."

For about 85 percent to 90 percent of people who have total knee replacements, the artificial joints last about 15 to 20 years. In elderly patients, that may mean the rest of their lives. But for younger patients, especially those who are very active, the implants may fail over time and require revision. Over the last five years or so, the team of HSS researchers have been collaborating to understand the factors placing some patients at higher risk of poor outcomes, including needing revisions.

This study was the first to link patient data to a statewide discharge database. The researchers linked the HSS Knee Replacement Registry with the Statewide Planning and Research Cooperative System (SPARCS) database and captured discharge information for patients who received revisions at other hospitals within the state of New York. Also new with this study, they explored whether race and poverty played a role in knee replacement failure, a broader outcome definition that includes patients who failed to improve at all after their initial procedures but who did not have revisions. Poverty information was collected from the U.S. census data.

Among a total of 4,062 patients who had a total knee replacement between January 2008 and February 2012 at HSS, only 122 or 3 percent required revisions during a median of five years of follow-up. Black patients had a 1.7 times higher risk of knee replacement revision than white patients, but when the researchers analyzed multiple variables, race and poverty were not driving factors. Race and poverty also did not explain differences among patients with knee replacement failure.

The factors that were associated with a higher risk for revision were younger age, being male, and the use of a constrained prosthesis--a knee implant with conforming components that provides more stability. The risk factors driving failure included being treated by a surgeon that performs a low number of knee replacement surgeries and patients' low expectations for improvement after surgery.

"Younger people and males are typically more active, putting more strain on their implants. Constrained prostheses are only used in patients with bigger deformities and ligament imbalances, which tend to put more strain on the implant and loosen the bone-cement interface," said study author Mark P. Figgie, MD, an attending orthopedic surgeon and Chief Emeritus of the Surgical Arthritis Service at HSS, and professor of clinical orthopedic surgery at Weill Cornell Medicine. "Our findings suggest that all patients should seek care from experienced surgeons at a high-volume hospital."

To explore their findings on a larger scale, the research team is conducting a new study, linking data from about one million patients from California, New York, Florida, Arizona, and Arkansas with their respective statewide databases. "We are asking the same questions about race and poverty, and we will be able to look at the influence of hospital choice on the risk of revision by linking to the American Hospital Association database," Dr. Bass said. "We are also looking at differences in revisions caused by infections versus mechanical issues." The more extensive study is expected to be completed later this year.

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This study was made available online in July 2019 ahead of the publication in the November issue on October 29, 2019.

About HSS

HSS is the world's leading academic medical center focused on musculoskeletal health. At its core is Hospital for Special Surgery, nationally ranked No. 1 in orthopedics (for the tenth consecutive year), No. 3 in rheumatology by U.S. News & World Report (2019-2020) and named a leader in pediatric orthopedics by U.S. News & World Report "Best Children's Hospitals" list (2019-2020). Founded in 1863, the Hospital has one of the lowest infection rates in the country and was the first in New York State to receive Magnet Recognition for Excellence in Nursing Service from the American Nurses Credentialing Center four consecutive times. The global standard total knee replacement was developed at HSS in 1969. An affiliate of Weill Cornell Medical College, HSS has a main campus in New York City and facilities in New Jersey, Connecticut and in the Long Island and Westchester County regions of New York State. In addition, HSS will be opening a new facility in Florida in early 2020. In 2018, HSS provided care to 139,000 patients and performed more than 32,000 surgical procedures, and people from all 50 U.S. states and 80 countries travelled to receive care at HSS. There were more than 37,000 pediatric visits to the HSS Lerner Children's Pavilion for treatment by a team of interdisciplinary experts. In addition to patient care, HSS leads the field in research, innovation and education. The HSS Research Institute comprises 20 laboratories and 300 staff members focused on leading the advancement of musculoskeletal health through prevention of degeneration, tissue repair and tissue regeneration. The HSS Global Innovation Institute was formed in 2016 to realize the potential of new drugs, therapeutics and devices. The HSS Education Institute is the world's leading provider of education on musculoskeletal health, with its online learning platform offering more than 600 courses to more than 21,000 medical professional members worldwide. Through HSS Global Ventures, the institution is collaborating with medical centers and other organizations to advance the quality and value of musculoskeletal care and to make world-class HSS care more widely accessible nationally and internationally. http://www.hss.edu.

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