Study Shows Knee Osteoarthritis Causes More Pain and Inflammation in Women

WASHINGTON, Nov. 18, 2024 /PRNewswire/ -- Women with knee osteoarthritis (OA) experience more pain and inflammation than men, according to a new study led by researchers at Hospital for Special Surgery (HSS) and The Rockefeller University. The work indicates that different genes and biological processes may cause knee OA to be worse in women compared to men and suggests that women may benefit from personalized treatments that target those specific mechanisms.

"These findings give some reassurance to female patients that there are physiological reasons why they are having more pain," says Bella Mehta, MBBS, MS, rheumatologist at HSS and lead author of the study. "Our work may also help us develop better therapies, especially for women with more severe symptoms."

The study enrolled 135 patients with knee OA who were scheduled to have total knee replacement. A total of 82 participants were female. Researchers analyzed patient-reported symptoms of pain, histology (tissue samples removed during surgery and examined under the microscope) and genetic markers of inflammation in the blood.

The study found that women with knee OA had higher markers of inflammation in their blood, increased tissue inflammation and widespread cartilage loss. This corresponds with the study's findings that women reported higher levels of pain, even at night when at rest.

The findings also revealed specific genetic expression patterns in women that notably increased synovial tissue inflammation. This occurs when the synovium, the thin layer of tissue above the cartilage that helps lubricate the knee joint, becomes inflamed and painful.

"Traditionally, it was thought that knee osteoarthritis was caused by years of significant wear and tear on the cartilage in the knee joint, but synovial inflammation is now known to play a big role in this condition," notes Dr. Mehta.

Knee osteoarthritis is the most common type of arthritis in the world. Most people over the age of 65 have some form of it, with around 70% to 80% experiencing symptoms of pain and stiffness.

Pain is typically reported more frequently in women with knee OA than in men. Dr. Mehta suggests several theories as to why, including:

• Mechanical differences between men and women. A woman's pelvis or hip bone is shaped differently than men so they can accommodate having babies. This has implications on the knee joint, which may increase osteoarthritis and pain.
• Hormonal differences in estrogen and progesterone after menopause, which may make women more prone to osteoarthritis.
• Differences in genetics. Women are born with two X chromosomes, whereas men have an X and a Y chromosome. The second X chromosome expresses certain genes that increase the likelihood for women to have osteoarthritis.

"It's not that women complain of more pain. There are objective, physiological differences that we have seen between men and women that can explain this," says Dr. Mehta. "For example, they have increased markers of inflammation in their blood, inflammatory gene expression and more mechanical stress and cartilage loss in the knee, all contributing to more pain even at rest."

Currently, first-line treatments for people with knee OA include medications to manage pain, and exercise to strengthen the muscles and ligaments around the knees. However, if there is no improvement, surgery is recommended.

Researchers continue to look for ways to improve treatment options for knee OA. "There may be certain immunomodulatory agents that target the genetic mechanisms driving tissue inflammation in women, but more research is needed to better understand these genes and their role in accelerating knee osteoarthritis in females," says Dr. Mehta.  

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 15th consecutive year), No. 3 in rheumatology by U.S. News & World Report (2024-2025), and the best pediatric orthopedic hospital in NY, NJ and CT by U.S. News & World Report "Best Children's Hospitals" list (2024-2025). In a survey of medical professionals in more than 20 countries by Newsweek, HSS is ranked world #1 in orthopedics for a fifth consecutive year (2025).

Founded in 1863, the Hospital has the lowest readmission rates in the nation for orthopedics, and among the lowest infection and complication rates. HSS was the first in New York State to receive Magnet Recognition for Excellence in Nursing Service from the American Nurses Credentialing Center five consecutive times. 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, as well as in Florida.

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. In addition, more than 200 HSS clinical investigators are working to improve patient outcomes through better ways to prevent, diagnose, and treat orthopedic, rheumatic and musculoskeletal diseases. The HSS Innovation Institute works to realize the potential of new drugs, therapeutics and devices. The HSS Education Institute is a trusted leader in advancing musculoskeletal knowledge and research for physicians, nurses, allied health professionals, academic trainees, and consumers in more than 165 countries. 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. www.hss.edu.

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SOURCE Hospital for Special Surgery