Are biomechanical factors, meniscal pathology, and physical activity risk factors for bone marrow lesions at the knee? A systematic review.

OBJECTIVE: To systematically review the literature to determine whether biomechanical factors, meniscal pathology, and physical activity are risk factors for bone marrow lesions (BMLs) at the knee identified from magnetic resonance imaging in pre-osteoarthritis and osteoarthritis populations.
METHODS: Electronic searches of MEDLINE and EMBASE were performed from January 1, 1996 to October 31, 2012 using the keywords of bone marrow lesion(s), bone marrow (o)edema, osteoarthritis, and knee. Studies examining biomechanical factors, meniscal pathology, or physical activity in relation to the presence, incidence, or change in BMLs at the knee were included. Two independent reviewers extracted the data and assessed the methodological quality of selected studies. Due to the heterogeneity of the studies, we performed a best evidence synthesis.
RESULTS: Fifteen studies were included in this review, of which 9 were considered high quality. The study populations were heterogeneous in terms of the symptoms and radiographic knee osteoarthritis. There was strong evidence for relationships of mechanical knee alignment and meniscal pathology with BMLs in osteoarthritis populations. There was a paucity of evidence for a relationship between physical activity and BMLs.
CONCLUSION: Despite the heterogeneity of included studies, these data suggest that mechanical knee alignment and meniscal pathology are risk factors for BMLs in knee osteoarthritis. It suggests that BMLs in individuals with osteoarthritis are more susceptible to mechanical knee alignment. Given the role of BMLs in the pathogenesis of knee osteoarthritis, identifying strategies to modify these risk factors will be important in slowing the progression and reducing the burden of knee osteoarthritis.