The Association of Bone Marrow Lesions with Pain in Knee Osteoarthritis

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The summary below is from the full report titled "The Association of Bone Marrow Lesions with Pain in Knee Osteoarthritis." It is in the 3 April 2001 issue of Annals of Internal Medicine (volume 134, pages 541-549). The authors are DT Felson, CE Chaisson, CL Hill, SMS Totterman, ME Gale, KM Skinner, L Kazis, and DR Gale.

What is the problem and what is known about it so far?

Osteoarthritis is a common condition in which changes in the joints lead to pain and disability. The cause of osteoarthritis is unknown. It is also unclear why people with osteoarthritis develop pain, because osteoarthritis mainly affects the cartilage in joints and cartilage does not contain any nerves responsible for conducting pain. Knowing more about when and why pain develops in osteoarthritis might help us to develop better treatments for this condition. Some patients with knee injuries or knee osteoarthritis develop abnormalities, called lesions, in the central portion of the bone (bone marrow) that can be seen on magnetic resonance imaging (MRI). This radiologic test uses magnetic field and radio waves to create pictures of internal organs. These bone marrow lesions are thought to represent areas of contusion (sort of like internal bruises). It is unknown whether bone marrow lesions seen on MRI are associated with the occurrence of pain in osteoarthritis.

Why did the researchers do this particular study?

To find out whether bone lesions seen on MRI are associated with pain in patients with osteoarthritis of the knee.

Who was studied?

The study included 401 patients with knee osteoarthritis that could be seen on regular x-rays. Of these 401 patients, 351 had knee pain and 50 had no knee pain.

How was the study done?

The researchers obtained regular x-rays and MRIs on the knees of all study participants. They asked standard questions to have patients with knee pain quantify the severity of the pain. They then compared the frequency of bone marrow lesions and large bone marrow lesions in painful and nonpainful knees. They also explored whether the number and size of bone marrow lesions were associated with the degree of knee pain that patients reported.

What did the researchers find?

More than three quarters of persons with painful knees had bone marrow lesions, compared with fewer than one third of persons with nonpainful knees. Large bone marrow lesions occurred almost exclusively in painful knees. The number and size of the lesions were not associated with the severity of pain.

What were the limitations of the study?

The study included no patients who had severe changes on x-ray but no pain, so the findings might not apply to such patients. In addition, the study did not follow patients to see what happens to bone lesions and pain over time.

What are the implications of the study?

Bone marrow lesions on MRI are strongly associated with the presence of pain in knee osteoarthritis. Knowing this may help researchers identify better treatments for knee osteoarthritis and the pain associated with it.