“Osteoarthritis is the most common type of arthritis that affects the knee joint,” said Dr. Grace Lo, assistant professor of medicine in the section of immunology, allergy and rheumatology at Baylor. “We wanted to see if complaints about popping or snapping in the knee joint, also known as crepitus, were predictive of symptomatic knee osteoarthritis, which is a combination of a frequent history of pain as well as radiographic evidence of knee osteoarthritis.”
Lo and colleagues analyzed four years of data from the Osteoarthritis Initiative, a large, publicly available data set, in those who had at least one knee without symptomatic knee osteoarthritis. In this group of participants, they found that crepitus was very predictive of the development of symptomatic knee osteoarthritis over the following year.
The researchers then looked further to determine which group of patients, those with just the radiographic evidence, those with just the pain or those with neither at the baseline visit, were more likely to end up with symptomatic knee osteoarthritis. They found that about 75 percent of symptomatic knee osteoarthritis cases came from those in the study who had radiographic evidence at baseline, but did not complain of frequent knee pain.
“This speaks to the natural history of what happens in osteoarthritis,” said Lo, who also is with the Center for Innovations in Quality, Effectiveness and Safety at the Michael E. DeBakey Veterans Affairs Medical Center in Houston, Texas. “First, you get some features of osteoarthritis on the radiograph and then you have some intermittent, minor symptoms that gradually worsen so that at some point you develop frequent knee pain. It makes sense that most people who developed symptomatic knee osteoarthritis had some radiographic evidence of osteoarthritis at their baseline visit.”
This study indicates that those who have evidence of osteoarthritis on a radiograph but do not have symptoms yet and hear creaking in their knee joints are in the group of people who are at risk of developing chronic symptoms, Lo said.
“This is a group that we need to target to modify risk factors, including obesity,” Lo said. “From a research perspective, this is an important group we need to recruit into clinical trials to help prevent the development of frequent knee pain from osteoarthritis.”
Others who took part in the study include Michael T. Strayhorn with Baylor and the Michael E. DeBakey VA Medical Center; Dr. Jeffrey B. Driban, Lori Lyn Price and Timothy E. McAlindon with Tufts Medical Center; and Dr. Charles B. Eaton with Alpert Medical School of Brown University.
The research was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health. The Osteoarthritis Initiative is a public-private partnership comprised of five contracts funded by the National Institutes of Health and private funding partners. The work was also supported in part by the Center for Innovations in Quality, Effectiveness and Safety, Michael E. DeBakey VA Medical Center.