Bone Marrow Lesions and Cartilage Loss

What problem was studied?
Knee osteoarthritis (OA), one of the most common forms of arthritis, occurs when the joint cartilage wears down, and there is associated joint pain and stiffness. It often leads to progressive disability.

Previous research has shown that the presence of abnormal areas of tissue change in the bone marrow (bone marrow lesions) at the knee joint are powerful predictors of progressive joint-space narrowing (an indirect measure of osteoarthritic cartilage damage) that can be seen on knee X-ray. Furthermore, lesions were generally found in areas of the knee joint that were malaligned. Yet their relationship to cartilage loss and the association between change in these lesions and cartilage loss are unknown.

What was done in the study?
To better understand these lesions, David J. Hunter, MBBS, PhD, and colleagues (including Arthritis Foundation-supported researcher Shreyasee Amin, MDCM, MPH, whose Arthritis Foundation funding supported this work) studied 217 patients with knee OA. They obtained magnetic resonance images (MRIs) of the knees at baseline, 15 months and 30 months to assess both bone marrow lesions and cartilage and took X-rays to assess mechanical alignment of the knee joint. They also conducted a physical examination and questioned participants about the severity of their knee symptoms at each visit.

What were the study results?
At the baseline MRI, more than half of the knees studied (57 percent) had bone marrow lesions, and the vast majority (99 percent) of those lesions were either the same or worse in subsequent MRIs. Knees with larger, more severe lesions at baseline had more cartilage loss over the 30-month follow-up period than did those without lesions or with less severe lesions at the study’s start. Enlargement of lesions over the course of the study correlated with worsening cartilage damage. The study also confirmed that the lesions are more likely to occur at locations within bones forming the joint where they are not properly aligned.

What does this mean to people with OA?
The results of this study suggest that bone marrow lesions are unlikely to get better over time and, instead, often get larger. It also shows that the location, size and effect of bone marrow lesions are mediated by limb alignment, suggesting that correcting limb alignment in people with OA could help the lesions and help prevent additional cartilage damage from OA. Further studies evaluating the impact of approaches to correct malalignment, such as knee braces, are needed.

Hunter DJ, Zhang Y, Niu J, et al. Increase in bone marrow lesions associated with cartilage loss: a longitudinal magnetic resonance imaging study of knee osteoarthritis. Arthritis Rheum 2006;54:1529–35. PMID: 16646037
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