Sept. 10, 2008 -- An aging knee may be more likely to suffer a torn meniscus, but that meniscal tear might not be painful, a new study shows.
And the researchers go one step further. They say that for people whose knee pain is likely caused by osteoarthritis, "evidence is lacking" that surgery to remove meniscal damage will help.
The study -- published in The New England Journal of Medicine -- focuses on the meniscus, which is a bit of connective tissue shaped like a half moon in the knee.
Meniscal tears are often treated by arthroscopic surgery, and the new study is all about figuring out just how common meniscal tears are after age 50.
The short answer: They're common, become more common with age, and are often accompanied by osteoarthritis. But they don't always hurt, say the researchers, who included Martin Englund, MD, PhD, of Boston University's medical school.
Meniscus Tears Common
Englund's study isn't so much about knee-wrenching injuries that bench athletes. It's more about the toll that the knees endure over the years.
For the study, nearly 1,000 adults aged 50-90 in Framingham, Mass., got magnetic resonance imaging (MRI) of their right knee.
On average, 35% had meniscal tears or meniscal destruction.
Meniscal tears were more likely among men than among women and increased with age. For instance, 19% of women in their 50s had meniscal tears, compared to 56% of men aged 70-90.
Meniscal damage was especially likely among people whose scans showed evidence of knee damage from osteoarthritis.
But when Englund's team asked participants about their knee pain, they got some surprising answers.
Torn Meniscus, No Pain?
Participants reported any knee pain, aching, or stiffness that they'd had in the previous month.
Most people with a torn meniscus -- 61% -- didn't report any of those knee problems. And meniscal tears were about as common among people who usually had knee pain and who never had knee pain.
Meniscal damage was only "minimally lower" in people who had had knee surgery in the past, Englund and colleagues write.
The study does have some limits, like only focusing on the right knees of adults from a predominantly white town.
Still, Englund's team argues that surgery to remove the damaged meniscus may not ease the knee pain of people whose symptoms are probably a result of their osteoarthritis.
The decision to get arthroscopic surgery should be done on a case-by-case basis, according to an editorial published with the study.
"Surgeons must practice evidence-based care and use sound clinical judgment to make the best decisions for individual patients," writes editorialist Robert Marx, MD, of Cornell University's Weill Medical College.