NEW YORK (Reuters Health) – Damage to the meniscus, a shock-absorbing cartilage in the knee, is a common finding on MRIs in middle-aged and elderly persons and, in most cases, it causes no symptoms, investigators report in The New England Journal of Medicine.

According to an accompanying editorial, meniscal tears and knee pain can often coexist without the former being the cause of the latter. As such, doctors should look for other causes, such as arthritis, before contemplating surgery to address the tear.

To determine the frequency of meniscal damage and its association with knee pain and stiffness, Dr. Martin Englund, at the Boston University School of Medicine, and co-investigators studied MRI scans of the right knee of 991 randomly selected, ambulatory adults, between ages 50 and 90, living in Framingham, Massachusetts.

MRI revealed meniscal damage in 35 percent of subjects. Damage to the meniscus was more common among men than women, and increased with age, affecting more than 50 percent of subjects over the age of 69.

Most of the meniscal tears were in people who had not had any pain, aching, or stiffness in the previous month, the authors report.

Knee X-rays were performed for 963 of the subjects to look for arthritis. The authors found that up to 63 percent of subjects with arthritis had meniscal tears compared with no more than 32 percent of subjects without arthritis.

Although a meniscal tear may signal early arthritis, Englund’s team points out, “other structures or processes…may be causing the pain,” such as joint inflammation or bone marrow lesions. Surgical removal of the meniscus, a common procedure, is unlikely to have much effect on symptoms in patients with arthritis, they add.

“Identifying a tear in a person with knee pain does not mean that the tear is the cause of the pain,” Dr. Robert G. Marx, from Weill Medical College of Cornell University in New York, emphasizes in a Journal editorial.

SOURCE: The New England Journal of Medicine, September 11, 2008.