A person doesn't have to pack on very many extra pounds before their risk of needing a knee replacement increases substantially, a new evidence review has found.
Weight gain of just 11 pounds increases a woman's odds of needing total knee replacement surgery by one-third, and a man's by one-quarter, researchers reported Tuesday at the International Congress on Obesity in Melbourne, Australia.
Knee pain and stiffness also increased with this weight gain, while people's overall quality of life and ability to use their knee decreased, the researchers said.
Osteoarthritis occurs when the cartilage that cushions the joints wears away over time, allowing the ends of bones to rub against each other, causing pain, swelling and stiffness.
Losing 10% or more of total body weight has been found to improve knee arthritis, but if it gets too bad patients might need an artificial joint to replace the ruined one.
For this study, researchers reviewed 20 prior studies that examined the relationship between weight gain and osteoarthritis.
The studies found that weight gain had significant detrimental effects on the knee joint, including damage visible on X-rays.
"In other words, osteoarthritis was more likely to develop with weight gain and to progress more quickly,"said lead researcher Dr. Anita Wluka of the Monash University School of Public Health and Preventive Medicine, in Melbourne.
Combining results from two large studies involving more than a quarter of a million people, Wluka and her colleagues found that an 11-pound increase in weight made total knee replacement surgery 35% more likely for women and 25% more likely for men.
"This is particularly concerning,"Wluka said in a news release from the International Congress on Obesity. "Knee replacements are costly and one in five people are dissatisfied with the results and remain in pain after surgery. Those who remain in pain are more likely to require a second surgery, which is more costly and less likely to control their pain."
People at risk for osteoarthritis should be counseled on ways to manage their weight, Wluka concluded.
"Weight maintenance in middle age would reduce the risk of knee osteoarthritis occurring and, in those with osteoarthritis, it would reduce worsening of pain, loss of function and the need for costly joint replacement,"she said. "We know that people tend to put on nearly 1 kilogram (2.2 pounds) a year as they get older, but the good news is that there is evidence from previous studies that it is possible to prevent weight gain."
Research presented at medical meetings should be viewed as preliminary until published in a peer-reviewed journal.
More information
The American Academy of Orthopaedic Surgeons has more on total knee replacement.
SOURCE: International Congress on Obesity, news release, Oct. 18, 2022
