SAT0533 Knee Synovitis: Ultrasonographic Findings Strongly Correlate with Synovial Membrane Histology

BackgroundArthroscopy, by allowing direct visualization of the synovial membrane, is the gold standard for the assessment of knee synovitis. Given the fact that it is an invasive procedure, other reliable ways to assess synovitis has developed over the past few years. Ultrasonography (US) is a fast, available and low cost imaging tool and has been validated for detecting knee synovitis (1). Ultrasonographic and arthroscopic findings have been shown to correlate (2). However, few studies have yet assessed the correlation between ultrasonographic and histological findings.ObjectivesThe aim of this study was to assess the correlation between ultrasonographic scores, arthroscopic scores and histological scores for inflammation and vascularity in knee joint synovitis.MethodsPatients with knee pain and/or effusion were prospectively included. Knee was divided in three compartments (medial, lateral and superior). 1 operator (AN) performed a knee ultrasonography (B mode and Doppler mode) prior to the arthroscopy with a semi-quantitative assessment for degree of synovitis. 1 operator then performed a knee arthroscopy (CO, DJV) and scored macroscopic aspects with a 100-mm visual analogic scale (VAS) blindly from US findings and retrieved biopsies from each compartment. Biopsies were analyzed by 1 operator (UF) blindly from both US and arthroscopic findings and scored for: lining layer hyperplasia, inflammation and vascularity. Statistical analysis was made with non parametric Spearman correlation test.Results23 patients were included. 16 had rheumatoid arthritis (RA) (ACR/EULAR 2010 criteria). 3 patients had psoriatic arthritis (PsA) (CASPAR criteria), 3 had osteoarthritis (OA) and 1 had gout. Mean ultrasonographic, arthroscopic and histological scores for both synovitis and vascularity were calculated for each patient. A strong correlation was observed between: US synovitis grade and histological inflammation score (r=0.71; p=0.001), US Doppler grade and histological score for vascularity (r=0.6; p=0,0003); US measured synovial thickness and lining layer hyperplasia (r=0.61; p=0,002). Moreover, high positive correlations were observed for both histological lining layer hyperplasia and inflammation between lateral and medial compartments (r=0,90; p=0,00005 and r=0,66; p=0,014 respectively), lateral and superior compartments (r=0,75; p=0,001 and r=0,51; p=0,048, respectively) and medial et superior compartments (r=0,61; p=0,012 and r=0,62; p=0,010, respectively).Conc