Synovial hypertrophy, synovial effusions, and abnormalities in the subchondral bone play a key role in the pathogenesis of osteoarthritis (OA) and are associated with pain. Understanding and careful clinical assessment together with better imaging such as magnetic resonance imaging (MRI) of the knee may improve treatment strategies. The aim of this cross-sectional study was to investigate the associations between the structural findings on MRI (bone marrow lesions [BMLs], synovitis, cartilage defects, meniscal lesions), X-ray examination (Kellgren and Lawrence [K/L] grade), and psychological aspects with pain in patients with knee osteoarthritis (KOA).
In this study, patients with symptomatic KOA were included. Knee radiographs were acquired and scored according to the K/L score. MRI was performed with a 1.5 T whole-body scanner; the presence of the following alterations was collected: BMLs, infrapatellar fat pad (IFP) synovitis, condral defects, and meniscal tears. Knee pain was assessed with Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale. The Mental Component Summary Scale Score (MCS) of the Medical Outcomes Study Short-Form 36 Health Survey (SF-36) questionnaire was used to evaluate psychological impact.
BMLs were detected in 57 (38.3%) subjects of 149 participants (aged 51-81 years, female 75.8%). Cartilage defects were found in 91.9% of patients, IFP synovitis in 37.5%, meniscal lesions in 34.9%. In multiple regression analyses, WOMAC knee pain was significantly associated with the volume of the BMLs (p = 0.0001), IFP synovitis (p = 0.0036), and SF-36 MCS (p = 0.0001), but not with K/L grades, meniscal lesion score, cartilage defect, sex, age, educational level, disease duration and BMI.
In symptomatic KOA patients, MRI features, such as larger BMLs, IFP synovitis, and high levels of psychological distress, are associated with greater knee pain. Confirmation of these findings in the prospective studies of KOA is needed.