Using MRI reveals that cartilage damage may not be central to development of osteoarthritis, study suggests
A team of scientists has detected structural changes in the knee joint that precede signs of osteoarthritis seen in X-rays. For many years it has been understood that osteoarthritis stems primarily from wear and tear on the cartilage on the joint, but using magnetic resonance imaging (MRI) has revealed that changes throughout the joint are associated with osteoarthritis and therefore factors other than loss of cartilage may contribute to disease onset.
This new study by the Boston University School of Medicine and the University of Erlangen-Nuremberg, found that MRI reveal early changes to the joint that can predict the development of knee osteoarthritis, which challenges the widely held believe that damage to cartilage along initiates the disease.
Osteoarthritis is often diagnosed using characteristics visible on X-rays, such as narrowing of the joint space, which occurs as the cartilage breaks down, and development of bone spurs, which can form at the edges of the joint. But other joint tissue changes visible only on MRI, such as torn meniscus, signs of inflammation or bone marrow lesions, have been found to be important triggers in knee osteoarthritis.
The study, which is supported in part by the US National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), set out to assess if structural features detectable by MRI can predict the changes seen on X-rays. If so, the MRI findings could help identify people are risk of joint degeneration. MRI may also provide insights into the early stages of the disease.
The team, led by Dr Frank W Roemer, used data from the US National Institute of Health observational study of knee osteoarthritis occurrence and progression. The initiative included nearly 5,000 participants, ranged in age from 45 – 79 when they joined the study. MRI and X-ray knee images were taken at the first visit, and again yearly for four years.
The researchers compared the MRI images of 355 “case knees”—knees that developed osteoarthritis within the four-year period, as determined by characteristic signs seen on X-rays – to 355 matched control knees. They found that two years prior to the development of radiographic knee osteoarthritis, the case knees were more likely to have shown signs of inflammation and damage to the medial meniscus, a crescent-shaped segment of cartilage on the inner side of the knee joint.
The study found that inflammation and lesions in the bone marrow of the leg bones that border the joint were the most prominent predictors of the development of radiographic osteoarthritis on year later. Conversely, cartilage damage did not strongly correlate with the occurrence of radiographic knee osteoarthritis one to two years later, suggesting that cartilage breakdown plays a lesser or later role in the development of the disease than previously thought.
Patients with more abnormalities seen by MRI were more likely to develop radiographic osteoarthritis later on. The study showed that five or six structural knee abnormalities brought a six-fold increased risk of developing the disease two years later, compared to having one or no MRI-observable structural defects.
Dr Roemer says, “For many years, much of the research on therapies for osteoarthritis has focused on preserving the dignity of joint cartilage. Our work has provided a more detailed picture of how we view the events leading up to osteoarthritis, and has uncovered risk factors that will help us understand how the disease develops. Hopefully, it will lead to novel therapeutic targets.”
For more in-depth features, interviews and information, subscribe to Arthritis Digest magazine, a popular title that’s published six times a year. Click here for the digital version or tel 0845 643 8470 to order your had copy. You’ll know what your doctor is talking about, what new drugs are in the pipeline and be up to date on helpful products
