By studying MRIs from people who have not yet developed knee osteoarthritis according to x-rays, scientists from Northwestern Medicine found that some types of tissue lesions are associated with the development of persistent symptoms of the disease. The lesions also predict the initial development of cartilage damage before any changes of osteoarthritis appear on x-rays.
Osteoarthritis is the most common form of arthritis in humans and it frequently affects the knee. But little is known about its first stages. Early detection could prevent the pain and damage the disease causes in its fully established form.
“We looked at the significance of MRI legions – abnormalities in the cartilage, bone or meniscus of the knee that can show up using MRI – in older persons who were at higher risk for developing osteoarthritis but who did not have any signs of it on their knee x-ray,” said Leena Sharma, MD, ’89 GME, Solovy/Arthritis Research Society Research Professor in Medicine-Rheumatology. “Some believe that lesions like these appear with age and are not important. However, the significance of these lesions had not been evaluated previously in persons at higher risk for the disease.”
Currently, more than 27 million Americans have knee osteoarthritis, an arthritis that causes the cartilage protecting the knee joint to wear away.
People have a high risk of developing it if they are older, overweight or have had previous knee injuries, among other factors. Dr. Sharma points out that as the U.S. population gets older and heavier, more people will fit this description.
In the study, published in Arthritis & Rheumatology, the scientists evaluated 849 participants between the ages of 45 and 79 who were at high risk for knee osteoarthritis but had normal x-rays. The current method to diagnose the disease uses x-rays to classify the severity of common knee osteoarthritis features, including narrowing of the joint space and the presence of bone spurs. But those images don’t show other important lesions.
The scientists assessed the participants’ MRIs for visible abnormalities: cartilage damage, bone marrow lesions and meniscal damage. They also noted the participants’ symptoms, such as pain, aching or stiffness, throughout a 5-year period.
They found that the relationship between MRI-detected lesions and subsequent development of persistent knee osteoarthritis symptoms was significant. This was particularly true for patellofemoral lesions – those occurring in the compartment of the knee behind the kneecap. In addition, certain MRI lesions predicted the first development of cartilage damage in knees without any damage at the beginning of the study.
The findings point to targets for potential preventive and therapeutic strategies against knee osteoarthritis, at a phase when it may be easier to modify the course of the disease.
In other work, Dr. Sharma, director of the Multidisciplinary Clinical Research Center (MCRC), is investigating the role of mechanical factors in knee arthritis. She and a team of scientists through the MCRC hope to identify targets to delay cartilage loss and other poor outcomes of the disease.
This work was funded by National Institutes of Health grant R01-AR-52918. The participant data came from the Osteoarthritis Initiative.