In knee OA, the presence of bone marrow lesions (BMLs) predicts pain and progression of disease. Their occurrence has been described in healthy, pain-free subjects, but whether their presence affects change in cartilage is unknown.
Two hundred and seventy-one healthy community-dwelling adults with no history of knee injury, knee pain or clinical knee OA had an MRI performed on their dominant knee at baseline and 2 yrs later to assess the relationship between the presence of BMLs at baseline and change in tibiofemoral cartilage defects and tibial cartilage volume over 2 yrs.
BMLs were present in 37 (14%) subjects. Cartilage defects were more likely to progress rather than remain stable or regress in subjects with BMLs compared with those without BMLs (P = 0.04). The odds of cartilage defects progressing in the tibiofemoral compartment of the knee where BMLs were present compared with where BMLs were absent was 2.6 (95% CI 1.2, 5.3; P = 0.01). Where 'very large' BMLs were present, there was a trend for increased annual tibial cartilage volume loss (46.4 mm(3)/yr; P = 0.07).
These data suggest that BMLs are associated with change in knee cartilage over 2 yrs in asymptomatic subjects. Increased progression of cartilage defects is seen with increasing size of BMLs. It will be important to determine in future studies whether BMLs directly cause change in cartilage over 2 yrs, or act as a marker of another factor that facilitates these changes.