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Association of Bone Marrow Changes with Worsening of Knee Osteoarthritis
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What is the problem and what is known about it so far?
Knee osteoarthritis (“arthritis”) is a common condition in which changes in the knee joints lead to pain and difficulty walking. It is unknown why osteoarthritis worsens over time in some but not all people. Knowing more about when and why knee osteoarthritis worsens might help us develop better treatments for this condition. Magnetic resonance imaging (MRI) is a special type of test that uses a magnetic field and radio waves to create pictures of internal organs. Magnetic resonance imaging shows that some patients with knee osteoarthritis develop abnormalities in the central portion of the bone (bone marrow). These bone marrow changes (called bone marrow edema) are thought to represent areas of bone damage and have been associated with pain in people with knee arthritis. It is unknown whether bone marrow edema is associated with worsening of osteoarthritis over time. People with knee arthritis whose upper and lower leg bones do not line up properly (malalignment) are at risk for worsening of osteoarthritis over time. The relationship between malalignment and bone marrow edema is unknown.
Why did the researchers do this particular study?
To find out whether bone marrow edema seen on MRI is associated with malalignment of the leg bones and with worsening of knee osteoarthritis over time.
Who was studied?
223 patients who had knee osteoarthritis that could be seen on regular x-rays and who were participating in a larger study of knee osteoarthritis.
How was the study done?
The researchers obtained x-rays and MRIs of the knees of patients at the start of the study and again 15 and 30 months later. At the start of the study, they looked to see which patients had bone marrow edema on MRI and who had malalignment of the leg bones. They then looked to see whose osteoarthritis had worsened on the follow-up x-rays. They explored whether patients with bone marrow edema, malalignment, or both were more likely to have worsened osteoarthritis than patients without these findings.
What did the researchers find?
Patients with bone marrow edema on MRI were more likely to develop worsening osteoarthritis over the next 15 to 30 months than were patients without bone marrow edema. Malalignment was also associated with bone marrow lesions and with worsening osteoarthritis. However, even after the researchers accounted for malalignment, bone marrow lesions predicted worsening.
What were the limitations of the study?
This study shows that malalignment and bone marrow edema are associated with osteoarthritis progression but does not prove that these things actually cause the disease to worsen or that knowing about them will improve patient outcomes. X-rays and MRIs to check for malalignment should not be included as a routine part of the care of patients with knee osteoarthritis unless other studies prove that this information helps patients.
What are the implications of the study?
Bone marrow lesions on MRI, with or without limb malalignment, are associated with worsening of knee osteoarthritis over time. This information may help researchers identify better treatments for knee osteoarthritis.
Article and Author Information
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The summary below is from the full report titled “Bone Marrow Edema and Its Relation to Progression of Knee Osteoarthritis.” It is in the 2 September 2003 issue of Annals of Internal Medicine (volume 139, pages 330-336). The authors are D.T. Felson, S. McLaughlin, J. Goggins, M.P. LaValley, M.E. Gale, S. Totterman, W. Li, C. Hill, and D. Gale.
- Copyright ©2004 by the American College of Physicians
