New York —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 that patients who have a history of significant medical problems, especially congestive heart failure or pulmonary hypertension, are at increased risk for major complications.
“What we sought to do for the first time with this study, was to provide evidence-based risk stratification for who should be considered at high risk for morbidity and mortality when undergoing bilateral knee replacement surgery,” said Stavros Memtsoudis, M.D., Ph.D., an anesthesiologist at Hospital for Special Surgery, who led the study. “This is an elective procedure, so in the end, the primary concern should be for patient safety.” The study appears online ahead of print in the journal Anesthesia & Analgesia.
Bilateral knee replacement surgery or total knee arthroplasty (TKA) has advantages over staged unilateral knee replacement surgery (which is considered the alternative to bilateral knee arthroplasty) in terms of decreasing the time that patients spend in a hospital, decreasing hospital costs, and allowing patients to return to work and an active life more quickly. Studies have shown that bilateral knee replacements, however, are associated with greater morbidity and mortality than unilateral knee replacements.
To find out which patients are more at risk, researchers at Hospital for Special Surgery turned to the Nationwide Inpatient Survey, sponsored by the Agency for Healthcare Research and Quality (AHRQ). This is the largest inpatient database available in the United States that includes information on patients of all ages. It collects data from about 20% of all hospitalizations in the U.S. This large cohort of patient information is unparalleled and allows for the appropriate study of relatively rare events such as morbidity and mortality surrounding surgery. The study investigators analyzed data between 1998 and 2007 and found that more than 200,000 bilateral TKAs were performed during this time frame. The incidence of major in-hospital complications and mortality was 9.5 percent. The researchers analyzed outcomes with respect to patient demographics including comorbidities such as heart problems, diabetes, liver dysfunction, cancer, and alcohol abuse. They used a multivariate analysis to determine independent risk factors for major morbidity and mortality.
Patients undergoing bilateral TKA were 5.5 times more likely to have adverse outcomes if they had congestive heart failure and four times more likely to have worse outcomes if they had pulmonary hypertension. Patients were almost twice as likely to have complications if they were older than 75 years of age compared to individuals below the age of 65 years. Men had a 50 percent greater risk of complications than women.
“Age by itself will be a risk factor in any kind of surgery, so I am a little hesitant to say that patients who are over the age of 65 shouldn’t have bilateral knee replacement surgery, especially since a large number of knee replacement patients falls into that category. However, patients with extremes in age should be carefully evaluated before consideration for bilateral procedures.” said Dr. Memtsoudis. He added that the role of male gender is unclear, but could involve factors not accounted for in the analysis, such as hormonal differences.
What should be clear from the study, however, is that patients with congestive heart failure and pulmonary hypertension as well as significant other comorbidities are not good candidates for this bilateral surgery. “During orthopedic surgery, bone particles and marrow enter the bloodstream and embolizes (lodges) in the pulmonary vasculature and other organs thus impacting on blood flow through the lung and other systems. While these events stress the heart, they rarely cause any clinically noticeable effects in otherwise healthy patients. However, people who have a history of heart failure are already at a disadvantage,” explained Dr. Memtsoudis. “When a patient has pre-existing pulmonary hypertension, this may also make it more difficult for their heart to pump blood against even more increased pulmonary pressures brought upon by the occlusion of small vessels in the lungs.”
The HSS researchers say national guidelines need to be developed regarding bilateral knee replacement surgery and are organizing a meeting for 2012 to discuss the development of such guidelines. “Clinicians need to adopt an approach when doing this surgery that reconciles the benefits of bilateral knee replacement surgery and concerns for safety,” said Dr. Memtsoudis. “In order to do that, they will need to use evidence-based criteria of who should and who shouldn’t be considered an appropriate candidate for bilateral knee replacement. What we are providing with this study is the first step towards an evidence-based approach to risk stratifying patients.”
Almost 600,000 knee replacements are performed each year in the United States. These numbers are expected to rise as baby boomers, who are often reluctant to give up their active lifestyle, age.
The study was funded by the Department of Anesthesiology at HSS, the AHRQ Center for Education and Research in Therapeutics, and the National Institutes of Health.
Other Hospital for Special Surgery researchers involved with the study are Yan Ma, Ph.D. , Ya-Lin Chiu, M.S., Lazaros Poultsides, M.D., Ph.D., Alejandro Gonzalez Della Valle, M.D., and Madhu Mazumdar, Ph.D.
About HSS | Hospital for Special Surgery
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 ninth consecutive year) and No. 3 in rheumatology by U.S.News & World Report (2018-2019). 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 2017 HSS provided care to 135,000 patients and performed more than 32,000 surgical procedures. People from all 50 U.S. states and 80 countries travelled to receive care at HSS. 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 culture of innovation is accelerating at HSS as 130 new idea submissions were made to the Global Innovation Institute in 2017 (almost 3x the submissions in 2015). The HSS Education Institute is the world’s leading provider of education on the topic 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.