Synovitis associated with quadriceps weakness in persons with osteoarthritis of the knee: results from the AM-OA cohort

Purpose: To explore associations between tissue abnormalities (bone marrow lesions, effusion, synovitis, cartilage loss and osteophytes) visualised by MRI, with both biomechanical impairments (proprioceptive inaccuracy, laxity, quadriceps and hamstrings weakness) and clinical symptoms (pain, stiffness, activity limitations and crepitus) in a cohort of patients with knee osteoarthritis (OA). Methods: Cross-sectional study in 105 patients with knee OA from the Amsterdam Osteoarthritis cohort. Multivariable regression analyses were used to explore associations between MRI features in each compartment with OA symptoms. Results: Associations were found between presence of synovitis with quadriceps weakness (p1⁄4.004) and between severity of cartilage loss in the patellafemoral compartment with quadriceps weakness (p1⁄4.035). No associations were found for proprioceptive inaccuracy, laxity and hamstrings weakness. Medial tibiofemoral cartilage loss was the only MRI feature associated with pain and activity limitations. In contrary, all MRI features, except for synovitis, were found to be associated with the presence of crepitus. Conclusions: As we far as we know, this is the first study to find a significant association between synovitis and quadriceps weakness. This relationship was independent of pain severity. It may imply that strategies that decrease inflammation might be valuable to prevent clinical deterioration in OA patients. Since inflammation had not been identified by physical examination in most cases with MRI-assessed synovitis, MRI can play an important role in clinical assessment of knee OA patients.