It is widely believed that there are multiple sources of pain at a tissue level in osteoarthritis (OA). Magnetic Resonance Images (MRIs) provide a wealth of anatomic information and may allow identification of specific features associated with pain. We hypothesized that in knees with OA, bone marrow lesions (BMLs), synovitis, and effusion would be associated with weight-bearing and (less so with) non-weight-bearing pain independently.
In a cross-sectional study of persons with symptomatic knee OA using univariate and multivariate logistic regressions with maximal BML, effusion, and synovitis defined by Boston Leeds Osteoarthritis Knee Score as predictors, and knee pain using weight-bearing and non-weight-bearing Western Ontario and McMaster University OA Index pain questions as the outcome, we tested the association between MRI findings and knee symptoms.
160 participants, mean age 61 (+/-9.9), mean body mass index (BMI) 30.3 (+/-4.7) and 50% female, stronger associations were seen with weight-bearing compared with non-weight-bearing knee pain with adjusted risk ratios (RRs) of weight-bearing knee pain, for increasing maximal BML scores of 1.0 (referent) (maximal BML=0), 1.2, 1.9, and 2.0 (P for trend=0.006). For effusion scores, adjusted RRs of knee pain were 1.0, 1.7, 2.0, and 2.6 (P for trend=0.0004); and for synovitis scores, adjusted ORs were 1.0, 1.4, 1.5, and 1.9 (P for trend=0.22).
Cross-sectionally, maximal BML and effusion scores are independently associated with weight-bearing and less so with non-weight-bearing knee pain, supporting the idea that pain in OA is multifactorial. These MRI features should be considered as possible new treatment targets in knee OA.