I found this quote from the article to be particularly interesting...
"On Sept. 11, Dr. Felson and his colleagues published their results in The New England Journal of Medicine: meniscal tears were just as common in people with knee arthritis who did not complain of pain as they were in people with knee arthritis who did have pain. They tended to occur along with arthritis and were a part of the disease process itself. And so repairing the tears would not eliminate the pain."